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RT9911
6 Channel DC/DC Converters
General Description
The RT9911 is a complete power-supply solution for digital still cameras and other hand-held devices. It integrates one selectable Boost/Buck DC-DC converter, one highefficiency step-down DC-DC converter, one high-efficiency main step-up converter, one PWM converter for CCD positive voltage, one inverter for CCD negative voltage and one white LED driver for LCD backlight. The RT9911 is targeted for applications that use either two or three primary cells or a single lithium-ion battery. RT9911 is available in VQFN-40L 6x6. Each DC-DC converter has independent shutdown input.
Features
1.6V to 5.5V Battery Input Voltage Range Synchronous Boost/Buck Selectable DC-DC Converter Internal Switches Up to 95% Efficiency Syn-Buck DC-DC Converters 0.8V to 5.5V Adjustable Output Voltage Up to 95% Efficiency 100%(MAX) Duty Cycle Internal Switches Main Boost DC-DC Converter Adjustable Output Voltage Up to 97% Efficiency PWM Converter for CCD Positive Voltage Inverter for CCD Negative Voltage White LED Driver for LCD Panel Backlight Up to 1.4MHz Adjustable Switching Frequency 1A Supply Current in Shutdown Mode External Compensation Network for all Converters Independent Enable Pin to Shutdown Each Channel. 40-Lead VQFN Package RoHS Compliant and 100% Lead (Pb)-Free
Ordering Information
RT9911 Package Type QV : VQFN-40L 6x6 (V-Type) -Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard)
Note : Richtek Pb-free and Green products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. 100% matte tin (Sn) plating.
Pin Configurations
(TOP VIEW)
SELECT COMP2 PVDD2
30 29 28 27 26 25 24 41 23 22 21 11 12 13 14 15 16 17 18 19 20
EN6
EN5
EN4
EN3
EN2
EN1
Applications
Digital Still Camera PDA Protable Device
GND OK2 RT VREF VDDM GND FB1 COMP1 PGND1 LX1
1 2 3 4 5 6 7 8 9 10
40 39 38 37 36 35 34 33 32 31
FB2
GND
LX2 PGND2 FB3 COMP3 CS3 DRN3 DRP3 VFB6 CFB6 COMP6
COMP5
FB5
COMP4
PVDD1
PVDD5
VQFN-40L 6x6 DS9911-04 August 2007 www.richtek.com 1
PVDD3
EXT5
EXT4
EXT6
FB4
RT9911
Typical Application Circuit
VBAT VBAT 1.8V to 3.2V C1 to C2 10uFx2 VS 3.3V VS 3.3V C19 1uF 34 SELECT PVDD1 5 VDDM EXT4 18 C20 10uF L4 4.7uH SS0520 D6 Q4 C21 10uF C22 100pF R8 2.2M R9 205k
L1 4.7uH D9 11
CCD 12V 20mA
C3 to C6 10uFx4 R2 470k
C7 100pF
I/O 3.3V 500mA
Q1
R1 510k
C8 0.1uF
R3 150k
10 LX1 7 FB1 9 PGND1 29 PGND2 2 OK2 1 GND
FB4 17 3.3V RT9911 PVDD5 EXT5 RT 15 14
VBAT C23 C24 1uF 10uF Q5 SS0520 D7 C25 100pF R11 1M R12 125k VBAT C29 10uF R22 20k L5 3.3uH CCD -8V/40mA C26 to C27 10uFx2 C28 4.7uF
3 R10
VCORE 1.8V 300mA
L2 4.7uH C9 10uF R5 240k R4 300k C10 100pF
30 LX2 33 31
FB5
13
FB2 PVDD2
VREF 4 GND Bottom PAD 6
VS 3.3V
C11 10uF 20 VBAT C12 to C13 10uFx2 D5 L3 4.7uH 26
PVDD3 19 23 22 35 36 37 38 39 40
L6 4.7uH SS0520 D8 Q6 C30 4.7uF R13 300k D1 D2 D3 D4 EN1 EN2 EN3 EN4 EN5 EN6
Motor 5V 500mA
EXT6 CS3 VFB6 CFB6 EN1 EN1 EN3 EN4 EN5 EN6
R6 100pF 470k
C14
C15 to Q2 C18 10uFx4
25 DRN3 Q3 24 DRP3 28 FB3 COMP1 COMP2 COMP3 COMP4 COMP5 COMP6
R14 10
R7 90.9k
8 R15 to R21 C31 to C36
32 27 16 12 21 1M
Figure 1. Application Circuit for 2-Cells Battery Supply
Note : Bottom pad is GND pad, can be short to pin 6 (GND). Please remove Q2 when use Async Boost and remove D5 when use Sync Boost.
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VBAT VBAT 3.4V to 4.2V C1 to C2 10uFx2 L1 4.7uH C3 to C6 10uFx4 R2 150k VBAT C8 to C9 10uFx2 2.5V C13 0.1uF R3 510k C10 to C11 10uFx2 R5 226k R4 470k L2 4.7uH C12 100pF 33 FB2 VREF 4 9 PGND1 29 PGND2 Bottom PAD GND EXT6 CS3 VFB6 CFB6 EN1 EN1 EN3 EN4 EN5 EN6 23 22 35 36 37 38 39 40 6 19 VBAT C30 10uF 31 R1 470k C7 100pF 7 FB1 PVDD2 RT9911 PVDD5 EXT5 RT 15 14 3 R12 11 PVDD1 VBAT C22 1uF 34 SELECT 5 VDDM EXT4 18 C23 10uF L4 4.7uH SS0520 D6 Q4 C24 10uF C25 100pF R10 2.2M
CCD 12V 20mA
I/O 3.3V 500mA
10 LX1
FB4 17 VBAT C26 10uF Q5 SS0520 D7 FB5 13 C27 100pF R13 1M R14 125k R24 20k L5 3.3uH
R11 205k
30 LX2
C28 10uF C29 4.7uF
CCD -8V 40mA
Q1 DDR 2.5V 250mA
2 OK2 1 GND 20 PVDD3
VBAT
L6 4.7uH SS0520 D8 Q6 C31 4.7uF R15 300k D1 D2 D3 D4 EN1 EN2 EN3 EN4 EN5 EN6 R16 10
C15 to C16 10uFx2
D5
Motor 5V 500mA
L3 4.7uH 26
C17 10pF
R8 470k
C18 to C21 10uFx4
Q2
25 DRN3 Q3 24 DRP3 28 FB3 COMP1 COMP2 COMP3 COMP4 COMP5 COMP6
R9 90.9k
8 R17 to R23 C32 to C37
32 27 16 12 21 1M
Figure 2. Application Circuit for Li-ion Battery Supply
Note : Bottom pad is GND pad, can be short to pin 6 (GND). Please remove Q2 when use Async Boost and remove D5 when use Sync Boost. Output voltage setting CH1: 0.8Vx(1+R1/R2) ex: I/O 3.3V = 0.8x(1+470k/150k) CH2: 0.8Vx(1+R4/R5) ex: DDR 2.5V = 0.8x(1+470k/226k) CH3: 0.8Vx(1+R8/R9) ex: MOTOR 5V = 0.8x(1+470k/90.9k) CH4: 1.0Vx(1+R10/R11) ex: CCD 12V = 1.0x(1+2.2M/205k) CH5: -1.0Vx(R13/R14) ex: CCD -8V = -1.0x(1M/125k) DS9911-04 August 2007 www.richtek.com 3
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Functional Pin Description
Pin No. Pin Name 1 GND Pin Function Analog Ground Pin I/O -Internal State at Shut Down -GND
I/O Configuration
OK 2
2
OK2
External Switch Control. Frequency Setting Pin. Frequency is 500kHz if RT pin not connected. Device Input Power Pin Analog Ground Pin
OUT OUT IN --
High Impedance
VDDM
3 5 6
RT VDDM GND
Pull Low --+ -
RT GND
VDDM 1.0V + -
4
VREF
1.0V Reference Pin
OUT
High Impedance
VREF
7 8 9 10 11 12 13 14
FB1 COMP1 PGND1 LX1 PVDD1 COMP5 FB5 EXT5
Feedback Input Pin of CH1. Feedback Compensation Pin of CH1. Power Ground Pin of CH1. Switch Node of CH1. Power Input Pin of CH1. Feedback Compensation Pin of CH5. Feedback Input Pin of CH5. External Power Switch of CH5. Power Input Pin of CH4, CH5 and CH6. Feedback Compensation Pin of CH4. Feedback Input Pin of CH4.
IN OUT -OUT IN OUT IN OUT
High Impedance Pull Low -High Impedance -Pull Low High Impedance
0.8V FB1
+ -
COMP1
PVDD1
LX1
PGND1 FB5 COMP5
+ -
PVDD5
Pull High
EXT5
15 16 17
PVDD5 COMP4 FB4
IN OUT IN
-Pull Low High Impedance
1.0V FB4
+ -
COMP4
To be continued
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Pin No. Pin Name Pin Function I/O Internal State at Shut Down I/O Configuration
PVDD5
18
EXT4
External Power Switch of CH4.
OUT
Pull Low
EXT4
PVDD5
19
EXT6
External Power Switch of CH6.
OUT
Pull Low
EXT6
20
PVDD3
Power Input Pin of CH3.
IN
--
PVDD3
24
DRP3
External PMOS Switch Pin for CH3. OUT Feedback Compensation Pin of CH6. Current Feedback Input Pin for CH6.
Pull High
DRP3
21 22
COMP6 CFB6
OUT IN
Pull Low High Impedance
0.2V CFB6
+ -
COMP6
VFB6 1.0V + -
23
VFB6
Voltage Feedback Input Pin for CH6.
IN
High Impedance
50uA
PVDD3
25
DRN3
External NMOS Switch Pin for CH3. OUT
Pull Low
DRN3
VDDM
26
CS3
Current Sense Input Pin for CH3
IN
High Impedance
CS3
To be continued
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Pin No. Pin Name 27 28 29 30 31 32 33 COMP3 FB3 PGND2 LX2 PVDD2 COMP2 FB2 Pin Function Feedback Compensation Pin of CH3 Feedback Input Pin of CH3. Power Ground Pin of CH2 Switch Node of CH2 Power Input Pin of CH2. Feedback Compensation Pin of CH2. Feedback Input Pin of CH2. I/O OUT IN -OUT IN OUT IN Internal State at Shut Down Pull Low High Impedance -High Impedance -Pull Low High Impedance
VDDM 0.8V FB2
I/O Configuration
0.8V FB3 + COMP3
PVDD2
LX2
PGND2
+ COMP2
CH1 Boost/Buck Selection Pin. 34 SELECT Logic state can't be changed during IN operation.
2uA
Pull Low
SELECT
VDDM
35
EN1
Enable Input Pin of CH1.
IN
Pull Low
EN1
2uA
VDDM
36
EN2
Enable Input Pin of CH2.
IN
Pull Low
EN2
2uA
To be continued
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Pin No. Pin Name Pin Function I/O Internal State at Shut Down I/O Configuration
VDDM
37
EN3
Enable Input Pin of CH3.
IN
Pull Low
EN3
2uA
VDDM
38
EN4
Enable Input Pin of CH4.
IN
Pull Low
EN4
2uA
VDDM
39
EN5
Enable Input Pin of CH5.
IN
Pull Low
EN5
2uA
VDDM
40
EN6
Enable Input Pin of CH6.
IN
Pull Low
EN6
2uA
The exposed pad must be soldered Exposed Pad (41) GND to a large PCB and connected to GND for maximum power dissipation. ---
--
DS9911-04 August 2007
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Function Block Diagram
VDDM
EN4 PVDD5 EXT4 COMP4 FB4 1.0V REF EN5 PVDD5 EXT5 CH5 Inverter + 0.8V REF CH4 V-Mode Step-Up PWM
SELECT EN1 PVDD1 CH1 C-Mode Step-Up or Step-Down
LX1
+
PGND1 COMP1 FB1
COMP5 FB5
+ 1.0V REF CH2 C-Mode Step-Down
EN2 PVDD2
VREF
LX2
OK2 Switch Controller + 0.8V REF PVDD5 EXT6 CH6 WLED + 50uA 1.0V REF
PGND2 COMP2 FB2
EN6
EN3 PVDD3 DRP3 CH3 C-Mode Step-Up
VFB6
PVDD3 DRN3 CS3
COMP6 CFB6 0.2V REF + Oscillator Thermal Shutdown
+ 0.8V REF
COMP3 FB3
RT
GND
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Absolute Maximum Ratings
(Note 1) Supply Voltage, VDDM ----------------------------------------------------------------------------------------- -0.3V to 7V Power Switch ---------------------------------------------------------------------------------------------------- -0.3V to (VDD + 0.3V) The Other Pins -------------------------------------------------------------------------------------------------- -0.3V to 7V Power Dissipation, PD @ TA = 25C VQFN-40L 6x6 -------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 4) VQFN-40L 6x6, JA --------------------------------------------------------------------------------------------Junction Temperature -----------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------Storage Temperature Range --------------------------------------------------------------------------------ESD Susceptibility (Note 2) HBM (Human Body Mode) ----------------------------------------------------------------------------------MM (Machine Mode) ------------------------------------------------------------------------------------------2.778W 36C/W 150C 260C -65C to 150C 2kV 200V
Recommended Operating Conditions
(Note 3)
Dimming Control Frequency Range, CH6 ---------------------------------------------------------------- 300Hz to 900Hz Supply Voltage, VDDM ----------------------------------------------------------------------------------------- 2.4V to 5.5V Junction Temperature Range --------------------------------------------------------------------------------- -40C to 125C Operation Temperature Range ------------------------------------------------------------------------------- -40C to 85C
Electrical Characteristics
(VDDM = 3.3V, TA = 25C, unless otherwise specified)
Parameter Supply Voltage VDDM Minimum Startup Voltage VDDM Operating Voltage VDDM Over Voltage Protection Supply Current
Symbol VST VDDM (Note 5)
Test Conditions
Min -2.4 5.9
Typ --6.5
Max 1.6 5.5 --
Units V V V
VDDM Pin Voltage
Shutdown Supply Current into VDDM IOFF CH1 (Sync-Boost or Syn-Buck) Supply Current into VDDM CH2 (Sync-Buck) Supply Current into VDDM CH3 (Sync-Boost) Supply Current into VDDM CH4 (Asyn-Boost) Supply Current into VDDM CH5 (Asyn-Inverter) Supply Current into VDDM CH6 (Asyn-Boost) Supply Current into VDDM IQ1 IQ2 IQ3 IQ4 IQ5 IQ6
EN1 = EN2 = EN3 = EN4 = EN5 = EN6 = 0V VDDM = 3.3V, Non-Switching VDDM = 3.3V, Non-Switching VDDM = 3.3V, Non-Switching VDDM = 3.3V, Non-Switching VDDM = 3.3V, Non-Switching VDDM = 3.3V, Non-Switching
--------
1 -------
10 430 350 350 300 300 350
uA uA uA uA uA uA uA
To be continued
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Parameter Oscillator Operation Frequency CH1 Maximum Duty Cycle (Boost) CH1 Maximum Duty Cycle (Buck) CH2 Maximum Duty Cycle CH3 Maximum Duty Cycle CH4 Maximum Duty Cycle CH5 Maximum Duty Cycle CH6 Maximum Duty Cycle Feedback Regulation Voltage Feedback Regulation Voltage @ FB1, FB2, FB3 Feedback Regulation Voltage @FB4 Feedback Regulation Voltage @ FB5 VFB1, 2,3 VFB4 VFB5 0.788 0.98 -15 -0.18 0.984 0uA < IREF < 100uA ----0.8 1 -1 0.2 1 -0.2 22 22 0.812 1.02 +15 -0.22 1.016 10 ---V V mV V V
V mV
Symbol fOSC DMAX1 DMAX1 DMAX2 DMAX3 DMAX4 DMAX5 DMAX6
Test Conditions RT Open SELECT = 3.3V, VFB1 = 0.7V SELECT = 0V, VFB1 = 0.7V VFB2 = 0.7V VFB3 = 0.7V VFB4 = 0.9V VFB5 = 0.1V VCFB6 = 0.18V, VFB6 = 0.9V
Min 450 80 100 100 75 90
Typ 550 85 --80 94
Max 650 90 --90 98
Units kHz % % % % %
Feedback Regulation Voltage @ VFB6 VVFB6 Feedback Regulation Voltage @ CFB6 VCFB6 Reference VREF Output Voltage VREF Load Regulation Error Amplifier GM (CH1, CH2, CH3, CH4, CH5, CH6) Compensation Source Current (CH1, CH2, CH3, CH4, CH5, CH6) Compensation Sink Current (CH1, CH2, CH3, CH4, CH5, CH6) Power Switch CH1 On Resistance of MOSFET CH1 Switch Current Limitation (Buck) CH1 Switch Current Limitation (Boost) CH2 On Resistance of MOSFET CH2 Switch Current Limitation CH3 On Resistance of DRN3 CH3 On Resistance of DRP3 RDS(ON)NP3 P-MOSFET, PVDD3 = 3.3V RDS(ON)NN3 N-MOSFET, PVDD3 = 3.3V RDS(ON)PP3 P-MOSFET, PVDD3 = 3.3V RDS(ON)PN3 N-MOSFET, PVDD3 = 3.3V RDS(ON)P4 P-MOSFET, PVDD3 = 3.3V RDS(ON)N4 N-MOSFET, PVDD3 = 3.3V RDS(ON)P1 P-MOSFET, PVDD1 = 3.3V RDS(ON)N1 N-MOSFET, PVDD1 = 3.3V SELECT=0 SELECT=1 RDS(ON)P2 P-MOSFET, PVDD2 = 3.3V RDS(ON)N2 N-MOSFET, PVDD2 = 3.3V VREF
ms uA uA
--1.3 2 --1.3 -------
200 200 2 2.5 300 300 2 6 6 6 6 6 6
300 300 4 4 450 450 4 15 15 15 15 15 15
m m A A m m A
CH4 On Resistance of MOSFET
To be continued
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Parameter Power Switch CH5 On Resistance of MOSFET RDS(O N)P5 P-MOSFET, PV DD5 = 3.3V RDS(O N)N5 N-MOSFET, PV DD5 = 3.3V RDS(O N)P6 P-MOSFET, PV DD5 = 3.3V RDS(O N)N6 N-MOSFET, PV DD5 = 3.3V OK2 = 1V ICS3 IVFB 6 ----90 5 40 6 6 6 6 -10 50 15 15 15 15 -15 60 uA uA uA Symbol Test Conditions Min Typ Max Units
CH6 On Resistance of MOSFET Switch Controller OK2 pin Sink Current External Current Setting (CH3) CS3 Sourcing Current VFB6 Sink Current Protection Under Voltage Protection Threshold Voltage @ FB1, FB2 Over Voltage Protection @ FB1, FB2 Control EN1, EN2, EN3, EN4, EN5, EN6 Input High Level Threshold EN1, EN2, EN3, EN4, EN5, EN6 Input Low Level Threshold EN1, EN2, EN3, EN4, EN5, EN6 Sink Current Select Pin Input High Level Threshold Select Pin Input Low Level Threshold Select Pin Sink Current Thermal Protection Thermal Shutdown Thermal Shutdown Hysteresis
SELECT = 0V SELECT = 0V
0.3 --
0.4 1
0.5 --
V V
VDDM = 3.3V VDDM = 3.3V VDDM = 3.3V
-0.4 --0.4
--2 --2 180 20
1.3 -6 1.3 -6 ---
V V uA V V uA C C
ISELECT TSD TSD
-125 --
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. JA is measured in the natural convection at T A = 25C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Note 5. A Schottky retifier connected from LX1 to PVDD1 is required for low-voltage startup, refer to Figure 1.
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Typical Operating Characteristics
CH1 Boost Efficiency vs. Output Current
100 90 80
100 90 80
CH1 Buck Efficiency vs. Output Current
Efficiency (%)
60 50 40 30 20 10 0
VIN = 3.2V = 2.5V = 2.0V = 1.5V
Efficiency (%)
70
70 60 50 40 30 20
VIN = 3.0V = 3.4V = 3.8V = 4.5V
Ch1 Boost VOUT = 3.3V
10 100 1000
10 0
Ch1 Buck VOUT = 2.5V
10 100 1000
Output Current (mA)
Output Current (mA)
CH1 Boost LX1 and Output Voltage Ripple
VIN = 1.8V, VOUT = 3.3V, IOUT = 100mA
CH1 Buck LX1 and Output Voltage Ripple
VIN = 4.2V, VOUT = 3.3V, IOUT = 100mA
VOUT (10mV/Div)
LX1 (2V/Div)
Time (1s/Div)
VOUT (10mV/Div)
LX1 (2V/Div)
Time (1s/Div)
CH1 Boost Load Transient Response
VIN = 3.0V, VOUT = 3.3V
CH1 Buck Load Transient Response
VIN = 4.2V, VOUT = 3.3V
VOUT (100mV/Div)
IOUT (100mA/Div)
Time (1ms/Div)
IOUT (200mA/Div)
VOUT (100mV/Div)
Time (1ms/Div)
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CH1 Boost Output Voltage vs. VDDM Voltage
3.30 3.29
CH1 Buck Output Voltage vs. Output Current
3.375 3.374
Output Voltage (V)
Output Voltages (V)
3.28 3.27 3.26 3.25 3.24 3.23 3.22 3.21 3.20 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6
3.373 3.372 3.371 3.370 3.369 3.368 3.367 3.366 3.365 0 100 200 300 400 500 600 700 800 900
VIN = 2.5V, VOUT = 3.3V, IOUT = 250mA
VIN = 3.7V, VOUT = 3.3V
VDDM Voltage (V)
Loading Current (mA)
CH1 Boost Output Voltage vs. Output Current
3.330 3.329 3.328
100 90 80
CH2 Buck Efficiency vs. Output Current
Output Voltages (V)
3.326 3.325 3.324 3.323 3.322 3.321 3.320 0 100 200 300 400 500 600 700 800 900
Efficiency (%)
3.327
70 60 50 40 30 20
VIN = 2.5V = 3.0V = 3.8V = 4.5V
VIN = 2.4V, VOUT = 3.3V
10 0
VOUT = 1.8V
10 100 1000
Output Current (mA)
Output Current (mA)
CH2 LX2 and Output Voltage Ripple
VIN = 3.3V, VOUT = 1.8V, IOUT = 300mA
CH2 LX2 and Output Voltage Ripple
VIN = 4.2V, VOUT = 2.5V, IOUT = 400mA
VOUT (10mV/Div)
LX2 (2V/Div)
Time (1s/Div)
VOUT (10mV/Div)
LX2 (2V/Div)
Time (1s/Div)
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CH2 Load Transient Response
VIN = 3.0V, VOUT = 2.5V
CH2 Load Transient Response
VIN = 3.3V, VOUT = 1.8V
VOUT (20mV/Div)
IOUT (200mA/Div)
Time (1ms/Div)
IOUT (100mA/Div)
VOUT (20mV/Div)
Time (1ms/Div)
CH2 Load Transient Response
VIN = 4.2V, VOUT = 2.5V
1.84 1.83 1.82
CH2 Output Voltage vs. VDDM Voltage
VIN = 3.3V, VOUT = 1.8V, IOUT = 250mA
VOUT (20mV/Div)
Output Voltage (V)
1.81 1.80 1.79 1.78 1.77 1.76 1.75 1.74
IOUT (200mA/Div)
Time (1ms/Div)
2.4
2.8
3.2
3.6
4
4.4
4.8
5.2
5.6
VDDM Voltage (V)
CH2 Buck Output Voltage vs. Output Current
3.370 3.360
CH2 Buck Output Voltage vs. Output Current
1.815 1.814
Output Voltages (V)
Output Voltages (V)
3.350 3.340 3.330 3.320 3.310 3.300 3.290 3.280 3.270 0
1.813 1.812 1.811 1.810 1.809 1.808 1.807 1.806 1.805 0
VIN = 3.7V, VOUT = 3.3V
100 200 300 400 500 600 700 800 900 1000 100 0
VIN = 3.7V, VOUT = 1.8V
100 200 300 400 500 600 700 800 900 1000 100 0
Output Current (mA)
Output Current (mA)
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CH3 Boost Efficiency vs. Output Current
100 90 80
100 90 80
CH3 Boost Efficiency vs. Output Current
Efficiency (%)
60 50 40 30 20 10 0 10 100
Efficiency (%)
70
VIN = 3.2V = 2.5V = 2.0V = 1.5V
70 60 50 40 30 20
VIN = 4.5V = 3.8V = 3.2V = 2.5V = 2.0V = 1.5V
VOUT = 3.3V
1000
10 0
VOUT = 5V
10 100 1000
Output Current (mA)
Output Current (mA)
CH3 Boost Efficiency vs. Output Current
100 90 80
CH3 LX3 and Output Voltage Ripple
VIN = 1.8V, VOUT = 3.3V, IOUT = 400mA
Efficiency (%)
60 50 40 30 20 10 0
VOUT = 3.3V
10 100 1000
VOUT (20mV/Div)
VIN = 3.0V Async = 2.4V Async = 1.5V Async = 3.0V Sync = 2.4V Sync = 1.5V Sync
LX3 (2V/Div)
70
Time (1s/Div)
Output Current (mA)
CH3 LX3 and Output Voltage Ripple
CH3 Load Transient Response
VIN = 3.0V, VOUT = 3.3V
VOUT (20mV/Div)
VIN = 1.8V, VOUT = 5V, IOUT = 350mA
IOUT (200mA/Div)
VOUT (100mV/Div)
LX3 (2V/Div)
Time (1s/Div)
Time (1ms/Div)
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CH3 Boost Output Voltage vs. VDDM Voltage
3.30 3.29 3.28
CH3 Boost Output Voltage vs. VDDM Voltage
5.08 5.07 5.06
VIN = 2.5V, VOUT = 3.3V, IOUT = 250mA
VIN = 2.5V, VOUT = 5.0V, IOUT = 250mA
Output Voltage (V)
3.27 3.26 3.25 3.24 3.23 3.22 3.21 3.20 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6
Output Voltage (V)
5.05 5.04 5.03 5.02 5.01 5.00 4.99 4.98 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
VDDM Voltage (V)
VDDM Voltage (V)
CH3 Boost Output Voltage vs. Output Current
5.020 5.015
CH4 Boost Efficiency vs. Output Current
100 90 80
VIN = 3.7V, VOUT = 5V
Output Voltage (V)
5.010
Efficiency (%)
5.005 5.000 4.995 4.990 4.985 4.980 4.975 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
70 60 50 40 30 20 10 0 1
VIN = 4.5V = 3.8V = 3.2V = 2.5V = 2.0V = 1.5V
VOUT = 12V
10 100
Output Current (A)
Output Current (mA)
CH4 LX4 and Output Voltage Ripple
VIN = 1.8V, VOUT = 12V, IOUT = 30mA
CH4 Load Transient Response
VIN = 1.8V, VOUT = 12V
VOUT (20mV/Div)
LX4 (5V/Div)
IOUT (20mA/Div)
VOUT (100mV/Div)
Time (1s/Div)
Time (1ms/Div)
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RT9911
CH4 Output Voltage vs. VDDM Voltage
11.88 11.87 11.86
CH4 Output Voltage vs. VDDM Voltage
15.42 15.41 15.40
VIN = 2.5V, PVDD5 = 3.3V, IOUT = 30mA
VIN = 2.5V, PVDD5 = 3.3V, IOUT = 30mA
Output Voltage (V)
11.85 11.84 11.83 11.82 11.81 11.80 11.79 11.78 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
Output Voltage (V)
15.39 15.38 15.37 15.36 15.35 15.34 15.33 15.32 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
VDDM Voltage (V)
VDDM Voltage (V)
CH4 Boost Output Voltage vs. Output Current
15.780 15.775
CH5 Inverting Efficiency vs. Output Current
100 90 80
VIN = 3.7V, VOUT = 15.5V
Output Voltages (V)
15.770
15.760 15.755 15.750 15.745 15.740 15.735 15.730 0 10 20 30 40 50 60 70 80 90 100
Efficiency (%)
15.765
70 60 50 40 30 20 10 0 1 10 100
VIN = 1.5V = 2.0V = 2.5V = 4.5V = 3.2V = 3.8V
VOUT = -8V
Output Current (mA)
Output Current (mA)
CH5 LX5 and Output Voltage Ripple
VIN = 1.8V, VOUT = -8V, IOUT = 50mA
CH5 Load Transient Response
VIN = 1.8V, VOUT = -8V
LX5 (5V/Div)
VOUT (20mV/Div)
IOUT (20mA/Div)
VOUT (100mV/Div)
Time (1s/Div)
Time (1ms/Div)
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RT9911
CH5 Output Voltage vs. VDDM Voltage
-8.02 -8.03 -8.04
CH5 Output Voltage vs. VDDM Voltage
-6.02 -6.03 -6.04
VIN = 3.0V, PVDD5 = 3.3V, IOUT = 30mA
VIN = 3.0V, PVDD5 = 3.3V, IOUT = 30mA
Output Voltage (V)
Output Voltage (V)
-8.05 -8.06 -8.07 -8.08 -8.09 -8.10 -8.11 -8.12 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
-6.05 -6.06 -6.07 -6.08 -6.09 -6.10 -6.11 -6.12 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
VDDM Voltage (V)
VDDM Voltage (V)
CH5 Output Voltage vs. Output Current
-8.152 -8.151 -8.150
100 90 80
CH6 Efficiency vs. Input Voltage
Output Voltages (V)
Efficiency (%)
-8.149 -8.148 -8.147 -8.146 -8.145 -8.144 -8.143 -8.142 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100
70 60 50 40 30 20
IOUT = 20mA
VIN = 3.7V, VOUT = -8V
10 0 1.5 2 2.5 3 3.5 4 4.5 5
Loading Current (mA)
Input Voltage (V)
CH6 LX6 and Output Voltage Ripple
VIN = 1.8V, VOUT = 3 x WLED, IOUT = 20mA
CH7 Load Transient Response
VIN = 2.5V, VOUT = 1.8V
VOUT (20mV/Div)
LX6 (5V/Div)
Time (1s/Div)
IOUT (200mA/Div)
VOUT (10mV/Div)
Time (1ms/Div)
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RT9911
CH1 and CH2 Power Sequence
EN1/EN2 (2V/Div) EN4/EN5 (2V/Div)
CH4 and CH5 Power Sequence
VOUT_Ch1 (2V/Div)
VOUT_Ch2 (2V/Div)
Start Up, VIN = 2.5V
VOUT_Ch5 (5V/Div)
VOUT_Ch4 (5V/Div)
Start Up, VIN = 2.5V
Time (1ms/Div)
Time (2ms/Div)
Feedback Voltage vs. Temperature
1.04 1.00
Feedback Voltage (V)
VFB4, VFB6
0.96 0.92 0.88 0.84 0.80 0.76 0.72 -40 -20 0 20 40 60 80 100
VFB1, VFB2, VFB3
Temperature (C)
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RT9911
Applications Information
The RT9911 includes the following six DC/DC converter channels to build a multiple-output power-supply system. CH1 : Selectable step-up or step-down synchronous current mode DC/DC converter with internal power MOSFETs. CH2 : Step-down synchronous current mode DC/DC converter with internal power MOSFETs. CH3 : Step-up asynchronous current mode DC/DC controller to drive external power MOSFETs. CH4 : Step-up asynchronous voltage mode DC/DC controller. CH5 : Inverting DC/DC voltage mode controller. CH6 : DC/DC voltage mode controller for WLED as well as conventional boost application; provides open LED OVP protection. CH1 : Selectable Step-up or Step-down Converter CH1 is selectable as step-up (SELECT pin = logic high) or step-down (SELECT pin = logic low). Step-up : With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM (continuous current mode). Step-down : With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM. While the input voltage is close to output voltage, the converter enters low dropout mode. Duty could be as long as 100% to extend battery life. See Figure 3(a) for detailed functional block. CH2 : Step-down DC/DC Converter With internal MOSFETs and synchronous rectifier, the efficiency is up to 95%. The converter always operates at fixed frequency PWM mode and CCM. While the input voltage is close to output voltage, the converter enters low dropout mode. Duty could be as long as 100% to extend battery life. See Figure 3(b) for detailed functional block. CH3 : Step-up DC/DC Controller With external MOSFETs and a synchronous rectifier, the efficiency is up to 97%. The converter always operates at fixed frequency PWM mode and CCM. The threshold of current limit is estimated by RDS(ON) of external NMOS. See Protections for detailed information and detailed functional block in Figure 3(c). CH4, CH6 : Step-up DC/DC Controller CH4 and CH6 are fixed frequency voltage mode PWM controllers. EXT4 and EXT6 pins are designed to drive external NMOS switch. CH6 is optimized for WLED application. CFB6 is current-sensing feedback, and VFB6 provides over voltage protection (WLED open circuit). See Protections for detailed information and detailed functional block in Figure 3(d for CH4 and e for CH6). CH5 : Inverting Controller CH5 is a voltage mode, fixed frequency PWM controller to generate negative output voltage. EXT5 is designed to drive external PMOS switch. To turn off PMOS completely, please note that PVDD5 should not be lower than the source voltage of PMOS. See Figure 3(f) for detailed functional block. Reference Voltage RT9911 provides a precise 1V reference voltage with souring capability 100uA. Connect a 1uF ceramic capacitor from VREF pin to GND. Reference voltage is enabled by connecting EN5 to logic high.
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RT9911
PVDD1 OSC COMP1 0.8V FB1 SELECT
PVDD2 OSC COMP2 0.8V FB2
+ -
SQ
+ -
R
Logic
Driver
+ -
SQ
+ -
LX1
R
Logic
Driver
LX2
Current Sense Slope compensation Fault Protection PGND1
Current Sense Slope compensation Fault Protection PGND2
Figure 3(a)
Figure 3(b)
PVDD3 OSC COMP3 0.8V FB3 CS3
OSC COMP4 1.0V FB4
PVDD5
+ -
SQ
+ -
DRP3 Logic Driver DRN3
+ -
SQ
+ -
R
R
Logic
Driver EXT4
Current Sense Slope compensation Fault Protection
PGND2
Triangle Wave
GND
Figure 3(c)
Figure 3(d)
PVDD5 OSC COMP6 CFB6 0.2V EN6
OSC COMP5 FB5 GND
PVDD5
+ + -
SQ
+ -
R
Logic
Driver EXT6
+ -
SQ
+ -
R
Logic
Driver EXT5
Diming Control Triangle Wave Fault Protection GND
Triangle Wave GND
Figure 3(e) Figure 3. Detailed Functional Block for each channel
Figure 3(f)
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RT9911
VBAT VDDM (VS 3.3V) EN1 to EN6 VS 3.3V T1d VCORE 1.8V VI/O 3.3V Motor 5V T3d CCD 12V CCD - 8V T4d T5d T5r WLED T4r T3r T2d T2r T1r
Note : Please refer to Figure 1 for application Information. Timing sequence should be controlled by EN pins.
T6d
T6r
Figure 4. Timing Diagram
Calculation method: Td1 to Td6 are precise value. Tr1 to Tr6 are approximation. Units : T in second, C in Farad, R in Ohm C31 to C36 : Compensation capacitor of CH1 to CH6. T1d = 0.7V x C31 / 2uA (CH1 Boost) T1d = 0.7V x C31 / 2uA (CH1 Buck) T2d = 0.35V x C32 / 2uA T3d = 0.7V x C33 / 2uA T4d = 0.35V x C34 / 2uA T5d = 0.85V x C35 / 2uA T6d = 0.85V x C36 / 2uA T1r = (0.5V x D1 + 0.48A x RDS(ON)_N x C31 /1.25uA @ No load (Boost) T1r = (0.33V x D1 + 0.2A x RDS(ON)_P x C31 /1.25uA @ No load (Buck) T2r = (0.33V x D2 + 0.2A x RDS(ON)_P x C32 /1.25uA @ No load
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T3r = (0.5V x D3 + 0.8A x RDS(ON)_N x C33 /3.6uA @ No load T4r = (1.0V x D4) x C34 / 1uA @ No load T5r = (1.0V x D5) x C35 / 1uA @ 1mA min. load T6r = (0.25V x D6) x C36 / 2.6uA @ 4 WLEDs where D1 = 1 - (VBAT / VVS 3.3V) (Boost) D1 = VVS 3.3V / VBAT D2 = VVCORE 1.8V / VBAT D3 = 1 - (VBAT / VMotor 5V) D4 = 1 - (VBAT / VCCD 12V) D5 = |VCCD -8V| / ( VBAT + |VCCD -8V|) D6 = 1 - (VBAT / VWLED) Example : T1d = 0.7V x 1nF / 2uA = 350 us (Boost) T1r = (0.5 x (1-1.8/3.3) + 0.48 x 0.2) x 1nF / 1.25uA = 258 us
DS9911-04 August 2007
(Buck)
RT9911
Oscillator The internal oscillator synchronizes CH1 to CH6 with fixed operation frequency. The frequency could be set by connecting resistor between RT pin to GND. See Figure 5 to adjust frequency. Soft Start With internal soft start mechanism, the soft start time of each channel is proportional to the compensation capacitor. Refer to the soft start waveform in Figure 4 for typical application. Protection RT9911 provides versatile protection functions. Protection type, threshold and protection methods are summarized in Table 1. Table 1
Protection type VDDM CH1: Boost Over Voltage Protection Current Limit Current Limit CH1: Buck Under Voltage Protection Over Voltage Protection Current Limit CH2 Under Voltage Protection Over Voltage Protection CH3 CH6 Thermal Current Limit Over Voltage Protection Thermal shutdown Threshold (typical) Refer to Electrical spec VDDM > 6.5V NMOS current> 2.5A PMOS current > 2.0A FB1 < 0.4V FB1 > 1.0V PMOS current > 2.0A FB2 < 0.4V FB2 > 1.0V CS3 > 0.3V, see below Note VFB6 > 1.0V, see Figure 8 Temperature > 180C Protection methods Disable all channels NMOS latched off PMOS latched off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS, PMOS latch off and all channels shutdown PMOS latched off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS, PMOS latch off and all channels shutdown NMOS latched off NMOS off All channels stop switching Reset method Restart if VDDM < 6.5V Automatic reset at next clock cycle VDDM power reset VDDM power reset VDDM power reset VDDM power reset VDDM power reset VDDM power reset Automatic reset at next clock cycle VFB6 < 1.0V Temperature < 160C
2500 2250 2000 1750 1500 1250 1000 750 500 250 0 10 100 1000
Oscillator Frequency vs. RRT
Oscillator Frequency (kHz)1
RRT (k)
Figure 5. Adjust Frequency
Note : If RDS(ON) x Iinductor > 0.3V, then current limit happens. For example, if select NMOS( AOS3402), RDS(ON) =110m (at VGS = 2.5V), then current limt happens if Iinductor > 2.73A. DS9911-04 August 2007 www.richtek.com 23
RT9911
VBAT
VDDM
VBAT
WLED EXT6
10uA LX3 CH3 PWM CS3 DRN3 Iinductor
R VFB6 1V 50uA
+
CH6 PWM
Figure 6. CH3 Current Limit Setting
CFB6
RT9911 Component Selection for Compensation : CH1 Sync-Boost (Select Pin = High Logic) : CH1 sync-boost converter employs current-mode control to simplify the control loop compensation. There is a RHPZ (Right Hand Plane Zero) appeared in the loop-gain frequency response when a boost converter operates with continuous inductor current (typically the case), we also call it works in CCM (Continuous Current Mode). For stability, cross over frequency (fC), unity gain frequency, must lower than this RHPZ frequency. The fixed parameters for CH1 boost compensation are as follows : Transconductance (from FB to COMP), GM = 200us Current sense transresistance, RCS = 0.4V/A Feedback voltage, VFB = FB = 0.8V
Figure 8. CH6 Over Voltage Protection Method (VWLED > 50A x R+1V, protection happens) The input parameters for CH1 boost compensation are as follows: R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load FOSC, operating frequency L, inductance RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) TDRP(%), Transient droop. The results we will get for CH1 boost compensation are as follows: R2, the voltage divider resistor in between FB and ground. CF, feedforward capacitor in parallel with R1.
VOUT
COMP CP
+ GM -
0.8V FB
R1
CF
RESR COUT
IOUT
RC, compensation resistor on COMP pin. CC, compensation capacitor in series with Rc and connect to ground. CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF).
RC CC
R2
Figure 7
COUT, output capacitance. This compensation is based on ceramic output capacitor.
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DS9911-04 August 2007
RT9911
The major steps for getting above results :
VFB 1. R2 = R1 x (VOUT - VFB)
RLOAD GM VFB RCS x x (1 - D) = 6.3nF. 4. CC = 2fC VOUT Choose 6.8nF.
Half-load transient means load from 0.25A to 0.5A transient. So, dI=0.5 - 0.25=0.25A dVFB = TDRP(%) x VFB = 5% x 0.8 = 0.04V. Thus,
2. Find RHPZ(Right Hand Plan Zero) location. RHPZ(Boost) = RLOAD x RLOAD = VOUT IOUT(MAX.) (1 - D) , Where 2L VIN VOUT
2
, D = Duty Cycle = 1 -
3. Set fC (cross over frequency) sufficiently below RHPZ. For example : fC = RHPZ/6 V FB R LOAD GM x x (1 - D) x 4. Get C C = R CS 2 f C V OUT 5. Select Rc based on the allowed transient droop. 1 RCS RC = dI x ( )x (1- D) GM x dVFB , where dI = transient step, dVFB = TDRP(%) x VFB RC x CC 6. Get COUT = RLOAD 7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffz VOUT ratio = = ffp VFB fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC Cf = , where ffz = 2 x x ffz x R1 ratio 9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). RESR CP = COUT . CP can be ignore if CP < 10pF. RC Example : Set R1 = 470k, VIN = 1.8V, VOUT = 3.3V, VFB = 0.8V, IOUT(MAX.) = 0.5A, fOSC = 500kHz, L = 4.7uH, RESR = 5m, and half-load transient droop is 5%. Results: 1. R2 = R1
VFB 0.8 = 470k = 150k VOUT - VFB 3.3 - 0.8
2
1 dI (1 - D) x RCS = 23k 5. RC = GM x dVFB
6. COUT =
RC x CC 23k x 6.8n = = 22 F . RLOAD 6 .6
7. ratio =
ffp VOUT 3.3 = = = 4.1 ffz VFB 0.8
8. CF =
1 = 126pF, where 2 x ff Z x R1 fC 11k ff Z = = = 2.68kHz ratio 4.1
Choose CF = 150pF COUT x RESR 22F x 0.005 = = 4.8pF , 9. CP = RC 23k which is less than 10pF. So, It can be ignored. CH1 Sync-Buck (Select Pin = Low Logic) and CH2 Sync-Buck : CH1 sync-buck (select pin=low logic) and CH2 sync-buck are converters employ current-mode control to simplify the control loop compensation. There is no RHPZ (Right Hand Plan Zero) in the buck topology but there is a high frequency pole f HP >= f OSC / . The f C (cross over frequency) is chosen sufficient less than fHP. The fixed parameters for CH1 and CH2 buck compensation are as follows: Transconductance (from FB to COMP), GM = 200us Current sense transresistance, RCS = 0.3V/A Feedback voltage, VFB = FB = 0.8V The input parameters for CH1 and CH2 buck compensation are as follows: R1, the voltage divider resistor in between VOUT and FB.
2. RHPZ(Boost) = RLOAD
(1 - D) = 66.3kHz, where 2L VOUT VIN RLOAD = = 6.6 , (1 - D) = = 0.54 IOUT(MAX) VOUT
RHPZ = 11kHz 6
3. fC =
DS9911-04 August 2007
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RT9911
VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load fOSC, operating frequency L, inductance RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) TDRP(%), Transient droop. The results we will get for CH1 boost compensation are as follows: R2, the voltage divider resistor in between FB and ground. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) COUT, output capacitance. This compensation is based on ceramic output capacitor. The major steps for getting above results : VFB 1. R2 = R1 VOUT - VFB 2. Set fc (cross over frequency) sufficiently below fOSC. fHP For example : fC = 4 3. CC =
RLOAD GM VFB x x RCS 2fC VOUT
8. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). COUT x RESR CP = . CP can be ignore if CP < 10pF. RC Example : Set R1 = 470k, VIN = 3V, VOUT = 1.8V, VFB = 0.8V, IOUT(MAX.) = 0.5A, fOSC = 500kHz, L = 4.7uH, RESR = 5m, and half-load transient droop is 5%.
Results : 1. R2 = R1 x
VFB 0.8 = 470k x = 376k VOUT - VFB 1.8 - 0.8
2. fC =
fHP fOSC = = 40kHz 4 4
3. CC =
RLOAD GM VFB x x = 4.25nF, where RCS 2fC VOUT VOUT RLOAD = = 3.6 IOUT(MAX.)
Choose 4.7nF. Half-load transient means load from 0.25A to 0.5A transient. So, dI = 0.5 - 0.25=0.25A dVFB = TDRP(%) x VFB = 5% x 0.8 = 0.04V. Thus, 4. RC = dI
RCS = 9.4k , choose 10k . GM x dVFB
5. COUT = RC x CC = 10k x 3.9nF = 10.8 F. Choose 10 F. RLOAD 3 .6 6. ratio =
ffp VOUT 1.8 = = = 2.25 ffz VFB 0.8
dI x RCS 4. RC = GM x dVFB , where dI = transient step, dVFB = TDRP(%) x VFB
7. CF =
RC x CC RLOAD 6. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp VOUT ratio = = ffz VFB fC 7. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC CF = , where ff Z = . 2 x ff Z x R1 ratio 5. Get COUT =
1 = 15.2pF, where 2 x ff Z x R1 fC 50k ff Z = = = 22.2kHz ratio 2.25
Choose CF = 22pF COUT x RESR 10 x 0.005 8. CP = = = 5pF , RC 10k which is less than 10pF. So, It can be ignored.
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CH3 Syn Boost Controller with External MOSFET : CH3 boost controller driving external logic level MOSFET employs current-mode control to simplify the control loop compensation. There is a RHPZ (Right Hand Plan Zero) appeared in the loop-gain frequency response when a boost converter operates with continuous inductor current (typically the case), we also call it works in CCM (Continuous Current Mode). For stability, cross over frequency (fC), unity gain frequency, must lower than this RHPZ frequency. The fixed parameters for CH3 boost compensation are as follows : Transconductance (from FB to COMP), GM = 200us Feedback voltage, VFB = FB = 0.8V The input parameters for boost compensation are as follows : RDS(ON), the NMOSFET RDS(ON), which is use to find transresistance, RCS. R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load FOSC, operating frequency L, inductance RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) TDRP(%), Transient droop. The results we will get for boost compensation are as follows : RCS, the transresistance of current sense. R2, the voltage divider resistor in between FB and ground. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF)
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COMP CP
+ GM -
COUT, output capacitance. This compensation is based on ceramic output capacitor. The major steps for getting above results : 1. RCS = 2 x RDS(ON) The rest of the steps are the same as sync-boost. CH4 Asyn-Boost Controller with External MOSFET CH4 is an asyn-boost controller driving external logic level N type MOSFET, which employs voltage mode control to regulate the output voltage. Compensation depends on designing the loading range working in discontinuous or continuous inductor current mode. (DCM or CCM). Asyn-Boost in DCM : We call it DCM because inductor current falls to zero on each switch cycle. The benefit of designing in DCM is the simple loop compensation, which has no RHPZ (Right Hand Plan Zero) and conjugate double pole in the frequency domain to worry about, but has a single load pole instead. However, the output ripple and efficiency are worse than in CCM (Continuous Inductor Current). If the loading is around tens of mA, it is not bad to design in DCM with less impact on the output ripple and efficiency, but gain more easy to stabilize the control loop. The fixed parameters for CH4 asyn-boost in DCM compensation are as follows: Transconductance (from FB to COMP), GM = 200us. Internal voltage ramp to decide duty cycle, VP = 1V. Feedback voltage, VFB = FB = 1V
VOUT
1V FB
R1
CF
RESR COUT
IOUT
RC CC
R2
Figure 9
RT9911
The input parameters for CH4 asyn-boost in DCM compensation are as follows : R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load fOSC, operating frequency L, inductance COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH4 asyn-boost in DCM compensation are as follows : R2, the voltage divider resistor in between FB and ground. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VFB 1. R2 = R1 x VOUT - VFB 2. Select suitable inductor to ensure IOUT(MIN.) works in DCM, which is let inductor current falls to zero on each switch cycle. VIN x D x (1 - D) L< 2 x IOUT(MAX.) x fOSC 3. Set fC sufficient below fOSC. fOSC For example: fC = or lower 10 4. Find the load pole : fLP = 2 x M-1 , 2 x (M - 1) x RLOAD x COUT VOUT VOUT where M = , RLOAD = . VIN IOUT(MAX.) Asyn-boost in CCM : We call it CCM because inductor current is always continuous in operation. The benefit of designing in CCM is lower VOUT and inductor current ripple and higher efficiency from the lower coil loss, but with the expense of larger inductor size and cost and the control loop comes with a RHPZ (Right Hand Plan Zero) and a conjugate double pole in the frequency domain to worry about. The fixed parameters for CH4 asyn-boost in CCM compensation are as follows : Transconductance (from FB to COMP), GM = 200us Internal voltage ramp to decide duty cycle, VP = 1V Feedback voltage, VFB = FB = 1V The input parameters for CH4 asyn-boost in CCM compensation are as follows: R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load IOUT(MIN.), minimum output laod fOSC, operating frequency
DS9911-04 August 2007
which is duty to VOUT transfer function. VIN D = duty cycle = 1 VOUT 6. Get CC = COUT x
RLOAD RC by letting comp zero = load pole.
7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp VOUT ratio = = ffz VFB fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio
CF = 1 fC , where ff Z = . 2 x ff Z x R1 ratio
9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC
fC x VP VOUT M-1 , where Gdod = 2 x x , 5. Get RC = fLP GM x Gdod D 2 x M-1
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RT9911
L, inductance COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH4 asyn-boost in CCM compensation are as follows: R2, the voltage divider resistor in between FB and ground. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VFB 1. R2 = R1 x VOUT - VFB 2. Select suitable inductor to ensure IOUT(MIN.) works in CCM, VIN x D x (1 - D) L> 2 x IOUT(MIN.) x fOSC 3. Find RHPZ(Right Hand Plan Zero) location. RHPZ(Boost) = RLOAD RLOAD = VOUT IOUT(MAX) (1 - D)2 , where 2L VIN VOUT 9. Find Cf by placing its zero on fcdp to cancel another double pole. 1 CF = . 2 x fcdp x R1 10.Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). RESR CP = COUT x . CP can be ignore if CP < 10pF. RC CH5 Asyn-Inverter Controller with External MOSFET CH5 is an asyn-inverter controller driving external logic level P type MOSFET, which employs voltage mode control to regulate the output voltage. Compensation depends on designing the loading range working in discontinuous or continuous inductor current mode. (DCM or CCM). Asyn-Inverter in DCM : We call it DCM because inductor current falls to zero on each switch cycle. The benefit of designing in DCM is the simple loop compensation, which has no RHPZ (Right Hand Plan Zero) and conjugate double pole in the frequency domain to worry about, but has a single load pole instead. However, the output ripple and efficiency are worse than in CCM (Continuous Inductor Current). If the loading is around tens of mA, it is not bad to design in DCM with less impact on the output ripple and efficiency, but gain more easy to stabilize the control loop. The fixed parameters for CH5 asyn-inverter in DCM compensation are as follows: Transconductance (from FB to COMP), GM = 200us Internal voltage ramp to decide duty cycle, VP = 1V Feedback voltage, VFB = FB = 0V Reference voltage, VREF = 1V
VOUT
, D = duty cycle = 1 -
4. Set fC (cross over frequency) sufficiently below RHPZ. RHPZ or lower. For example : fC = 6 2 x M-1 5. Find the load pole : fLP = , 2 x (M - 1) x RLOAD x COUT VOUT VOUT where M = , RLOAD = . VIN IOUT(MAX.)
fC x VP VIN fLP Get RC = , where Gdoc = , 6. GM x Gdoc (1 - D)2 which is duty to VOUT transfer function. VIN D = duty cycle = 1 . VOUT 1- D , 7. Find fcdp = 2 x (LC)2 which is the conjugate double pole from LC filter. 1 to cancel one of the double pole. 8. CC = 2 x fcdp x RC
COMP CP
+ GM RC CC
0V FB
R1
CF
RESR COUT
IOUT
R2
VREF = 1V 20k 4.7uF
Figure 10
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RT9911
The input parameters for CH5 asyn-inverter in DCM compensation are as follows : R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load fOSC, operating frequency L, inductance COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH5 asyn-inverter in DCM compensation are as follows : R2, the voltage divider resistor in between FB and VREF. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VREF - VFB . If R1 = 1M and VOUT = (-8)V 1. R2 = R1 x VFB - VOUT 1- 0 then R2 = 1M x = 125k 0 - (-8) 2. Select suitable inductor to ensure IOUT(MIN.) works in DCM, which is let inductor current falls to zero on each switch cycle. Asyn-Inverter in CCM : We call it CCM because inductor current is always continuous in operation. The benefit of designing in CCM is lower VOUT and inductor current ripple and higher efficiency from the lower coil loss, but with the expense of larger inductor size and cost and the control loop comes with a RHPZ (Right Hand Plan Zero) and a conjugate double pole in the frequency domain to worry about. The fixed parameters for CH5 asyn-inverter in CCM compensation are as follows : Transconductance (from FB to COMP), GM = 200us Internal voltage ramp to decide duty cycle, VP = 1V Feedback voltage, VFB = FB = 0V Reference voltage, VREF = 1V The input parameters for CH5 asyn-inverter in CCM compensation are as follows : R1, the voltage divider resistor in between VOUT and FB. VIN, input voltage. VOUT, desired output voltage IOUT(MAX.), maximum output load
DS9911-04 August 2007
fC x VP VOUT fLP Get RC = , where Gdod = , 5. GM x Gdod D which is duty to Vout transfer function.
D = duty cycle =
6. Get CC = COUT x
abs(VOUT) . VIN + abs(VOUT)
RLOAD RC by letting comp zero = load pole.
7. Find ffz, zero and ffp, pole ratio of voltage divider with CF. ffp abs(VOUT) + VREF ratio = = ffz VREF fC 8. Get CF by placing ffp on fC and ffz therefore on . ratio 1 fC CF = , where ff Z = . 2 x ff Z x R1 ratio 9. Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC
L<
VIN x (1 - D) 2 x IOUT(MAX.) x fOSC
3. Set fC sufficient below fOSC fOSC For example: fC = or lower 10 2 , 4. Find the load pole : fLP = 2 x RLOAD x COUT VOUT where RLOAD = . IOUT(MAX.)
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RT9911
IOUT(MIN.), minimum output laod fOSC, operating frequency L, inductance COUT, output capacitance. This compensation is based on ceramic output capacitor. RESR, ESR (Equivalent Series Resistance) of COUT (ceramic output capacitor) The results we will get for CH5 asyn-inverter in CCM compensation are as follows : R2, the voltage divider resistor in between FB and VREF. CF, feedforward capacitor in parallel with R1. RC, compensation resistor on COMP pin. CC, compensation capacitor in series with RC and connect to ground CP, connect in between COMP pin and ground. (Can be ignored if CP < 10pF) The major steps for getting above results : VREF - VFB . If R1 = 1M and VOUT = (-8)V 1. R2 = R1 x VFB - VOUT 1- 0 then R2 = 1M x = 125k 0 - (-8) 2. Select suitable inductor to ensure IOUT(MIN.) works in CCM, VIN x (1 - D) L< 2 x IOUT(MIN.) x fOSC 3. Find RHPZ(Right Hand Plan Zero) location. (1 - D)2 D , where RHPZ(Boost) = RLOAD 2L VOUT abs(VOUT) RLOAD = , D = duty cycle = IOUT(MAX) VIN + abs(VOUT) 4. Set fC (cross over frequency) sufficiently below RHPZ. RHPZ For example: fC = or lower 6 2 , 5. Find the load pole : fLP = 2 x RLOAD x COUT abs(VOUT) where RLOAD = . IOUT(MAX.) fC x VP VIN , where Gdoc = , 6. Get RC = fLP GM x Gdoc (1 - D)2 which is duty to VOUT transfer function. D = duty cycle = abs(VOUT) VOUT VIN + abs(VOUT)
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, 2 x (LC)2 which is the conjugate double pole from LC filter. 1 to cancel one of the double pole. 8. CC = 2 x fcdp x RC 9. Find Cf by placing its zero on fcdp to cancel another double pole. 1 CF = . 2 x fcdp x R1 10.Evaluate CP. CP is for canceling the zero from COUT (ceramic output capacitor). CP = COUT x RESR . CP can be ignore if CP < 10pF. RC
7. Find fcdp =
1- D
PCB Layout Considerations The feedback netwok should be very close to the FB pin. The compensation network should be very close to the COMP pin and avoid through VIA. For CH3 current sense, CS should be close to the drain site of external NMOS. Keep high current path as short as possible.
DS9911-04 August 2007
RT9911
Outline Dimension
D
D2
SEE DETAIL A L 1
E
E2
1
1 2
e A A3 A1
b
2
DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Symbol A A1 A3 b D D2 E E2 e L
Dimensions In Millimeters Min 0.800 0.000 0.175 0.180 5.950 4.000 5.950 4.000 0.500 0.350 0.450 Max 1.000 0.050 0.250 0.300 6.050 4.750 6.050 4.750
Dimensions In Inches Min 0.031 0.000 0.007 0.007 0.234 0.157 0.234 0.157 0.020 0.014 0.018 Max 0.039 0.002 0.010 0.012 0.238 0.187 0.238 0.187
V-Type 40L QFN 6x6 Package
Richtek Technology Corporation
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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DS9911-04 August 2007

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