View MIC2145_27709.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

MIC2145
Micrel
MIC2145
High Efficiency 2.5W Boost Converter Final
General Description
The MIC2145 is a small size boost switching regulator that can provide over 2.5W of output power. The input voltage range is between 2.4V to 16V, making the device suitable for one-cell Li-Ion and 3- to 4-cell alkaline/NiCad/NiMH applications. The output voltage of the MIC2145 can be adjusted up to 16V. The MIC2145 is well suited for portable, space-sensitive applications. Its typical 450kHz operation allows small surface mount external components to be used. The MIC2145 has a low quiescent current of 200A, and a typical shutdown current of 0.5A. The MIC2145 is capable of high efficiencies in a small board area. The MIC2145 features a low-on resistance internal switch that allows it to provide over 2.5W of output power. The peak switch current can be programmed through an external resistor. This allows the user to set the peak switch current at the level where maximum efficiency occurs. It also allows the user to further optimize for efficiency and inductor size by setting the peak current below the level of inductor saturation. The MIC2145 is available in an MSOP-8 and 3mmx3mm MLFTM-10L package with an ambient operating temperature range from -40C to +85C.
Part Number MIC2145BMM MIC2145BML
Features
* * * * * * * * * * 2.4V to 16V input voltage Output adjustable to 16V Programmable peak current limit Soft start Up to 450kHz switching frequency 0.5A shutdown current 200A quiescent current Capable of 5V/ 500mA output with 3.3V input Achieves over 85% efficiency Implements low power BOOST, SEPIC, and FLYBACK topologies * MSOP-8 and 3mmx3mm MLFTM-10L
Applications
* * * * * Flash LED driver LCD bias supply White LED driver DSL bias supply Local 3V to 5V conversion
Ordering Information
Voltage Adj Adj Ambient Temp. Range -40C to +85C -40C to +85C Package 8-lead MSOP 3x3 MLFTM-10L
Typical Application
VIN 3.0V to 5.0V CIN 10 F/6.3V
1
L1 10 H D1 EN PGND SW VDD FB SGND
5
10V Output Efficiency
90
VOUT 10V/150mA
EFFICIENCY (%)
85 80 75 70 65 60 10 VIN = 3.0V 100 1000 OUTPUT CURRENT (mA)
4
6
MIC2145BMM
3
COUT 10 F/16V
7
RSET SS
2
8
I Limit
Adjustable Output Boost Converter with Programmable Peak Switch Current
Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
May 2003
1
MIC2145
MIC2145
Micrel
Pin Configuration
EN 1 SS 2 RSET 3 PGND 4 8 SGND 7 FB 6 VDD 5 SW
EN 1 SS 2 RSET 3 PGND 4 PGND 5 10 SGND 9 FB 8 VDD 7 SW 6 SW
8-Lead MSOP (MM)
3mmx3mm MLF-10L (ML) x
Pin Description
Pin Number MSOP 1 2 3 4 5 6 7 8 Pin Number MLF 1 2 3 4, 5 6, 7 8 9 10 Pin Name EN SS RSET PGND SW VDD FB SGND Pin Function Enable (Input): Logic high (1.5V) enables regulator. Logic low (0.7V) shuts down regulator. Do not float. Soft Start Capacitor (External Component): Connect external capacitor to ground to control the rise time of the output voltage. Current Limit (External Component): Sets peak current limit of the internal power MOSFET using an external resistor. Power Ground (Return): Internal power MOSFET source. Switch Node (Input): Internal power MOSFET drain. Supply (Input): +2.4V to +16V for internal circuitry. Feedback (Input): Output voltage sense node. Small Signal Ground (Return): Ground
MIC2145
2
May 2003
MIC2145
Micrel
Absolute Maximum Ratings (Note 1)
Supply Voltage (VDD) .................................................... 18V Switch Voltage (VSW) .................................................... 18V Feedback Voltage (VFB) ................................................ 18V Switch Current (ISW) ........................................................ 2A Enable Voltage(VEN), Note 5 ........................................ 18V RSET Voltage (VRSET) .................................................... 6V ESD Rating, Note 3 ...................................................... 2kV Ambient Storage Temperature(TS) .......... -65C to +150C
Operating Ratings (Note 2)
Supply Voltage (VDD) ....................................... 2.4V to 16V Switch Voltage (VSW) .................................................... 16V Ambient Temperature (TA) ......................... -40C to +85C Junction Temperature (TJ) ....................... -40C to +125C Package Thermal Resistance MSOP JA (MSOP-8) .................................................... 206C/W JA (3mmx3mm MLF-10) .................................... 60C/W
Electrical Characteristics (Note 6)
VDD = 10V, VOUT = 10V, IOUT = 100mA; TJ =25C, unless otherwise noted, bold values indicate -40C TJ 125C. Parameter Supply Voltage Shutdown Current Quiescent Current Feedback Voltage Reference EN = 0.3V, VDD = 10V, VFB=1.35V EN = VDD, VDD = 10V, VFB = 1.35V (2%) (3%) Comparator Hysteresis Feedback Input Current Peak Current Limit VFB=1.35V RSET=200, VDD = 3.6V, Note 4 RSET=1k, VDD = 10V, Note 4 Current Limit Comparator Propagation Delay Switch On-Resistance ISW = 150mA, VDD = 3.0V ISW = 1.2A, VDD = 10V Maximum Off Time Enable Input Voltage Logic Low (turn-off) Logic High (turn-on) Enable Input Current VEN = 0V VEN = 2V Soft Start Current
Note 1. Note 2. Note 3. Note 4. Note 5. Note 6.
Condition
Min 2.4
Typ
Max 16
Units V A A V V mV nA A A ns
0.5 200 1.058 1.048 18 40 0.8 0.9 500 500 250 1000 1.1 1.5 -1 -1 -8 1.1 0.01 0.01 -12 1.08
5 300 1.102 1.112
750 400
m m ns
0.7
V V A A A
1 1 -16
VEN = 2V, VDD=3.0V
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5K in series with 100pF. The current is measured in a DC mode. Actual peak switching current will be higher due to internal propagation delay of the circuit. VEN VDD. Specification for packaged product only.
May 2003
3
MIC2145
MIC2145
Micrel
Typical Characteristics
Efficiency-Basic Configuration
100 90
EFFICIENCY (%) EFFICIENCY (%)
Efficiency-Bootstrapped Configuration
100 90
VOUT (V)
Load Regulation
10.2 10.0 9.8 9.6 9.4 9.2 VIN = 3.6V L = 10H
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0
80 70 60 50 VIN = 3.3V VOUT = 10V L = 10H
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
80 70 60 50 VIN = 3.3V VOUT = 10V L = 10H
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
0
OUTPUT CURRENT (A)
0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Line Regulation
SWITCH ON-RESISTANCE ()
15.8 15.6
VOUT (V)
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
SWITCH ON-RESISTANCE ()
16.0
1.0
Switch On-Resistance vs. VDD
Switch On-Resistance vs. Temperature
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
15.4 15.2 15.0 14.8 14.6 14.4 14.2 14.0
IOUT = 10mA
L = 10H 2 4 6 8 10 12 VDD (V) 14 16
0
2
4
6
8 10 12 14 16 18 VDD (V)
0.50
QUIESCENT CURRENT ()
Quiescent Current vs. VDD
FEEDBACK VOLTAGE (V)
Feedback Voltage vs. Temperature
1.1 1.09 1.08 1.07 1.06 1.05 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) FEEDBACK CURRENT (A) 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
Feedback Current vs. Temperature
0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00
0
2
4
6
8 10 12 14 16 18 VDD (V)
0.00 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
Off Time vs. Temperature
1.5 1.4 1.3 OFF TIME (s) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) SHUTDOWN CURRENT (A) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05
Shutdown Current vs. Temperature
0.50 QUIESCENT CURRENT (mA) 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05
Quiescent Current vs. Temperature
VIN = 3.6V
0.00 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0.00 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
MIC2145
4
May 2003
MIC2145
Micrel
Soft Start Current vs. Temperature
14 SOFT START CURRENT (A) 12 10 8 6 4 2 VIN = 3.6V PEAK CURRENT LIMIT (A)
Peak Current Limit vs. Temperature
1.4 RSET = 200 1.3 1.2 1.1 R = 500 1.0 SET RSET = 1k 0.9 0.8 0.7 0.6 0.5 0.4 V = 3.6V RSET = 10k 0.3 IN 0.2 VOUT = 10V 0.1 L = 10H 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 2000 PEAK CURRENT LIMIT (mA) 1800 1600 1400 1200 1000 800 600
Peak Current Limit vs. RSET
VIN = 15V 12V 10V 8.0V
L = 10H
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
400 VOUT/VIN > 1.25 100 1000 10000 RSET()
5.0V 4.2V 3.6V 3.3V 3.0V 2.4V
100000
May 2003
5
MIC2145
MIC2145
Micrel
Functional Diagram
VIN CIN VDD RSET
3 6
10H L1 D1 SW
5
VOUT
R1
CFF
COUT
RSET
Current Limit Comparator
R2
Thermal Shutdown
One Shot 800nS
Soft Start POWER MOSFET SGND
8
PGND Feedback Comparator
4
FB
7
/S
/Q
/R
VREF
EN
1
On(/Off)
R1 VOUT = 1.08 1 + R2
SS
2
CSS
Figure 1. Block Diagram
MIC2145
6
May 2003
MIC2145
Micrel
Output The maximum output voltage is limited by the voltage capability of the output switch. Output voltages of up to 16V can be achieved with the boost circuit. Higher output voltages require a flyback configuration. Peak Current Limit The peak current limit is externally set with a resistor. The peak current range is from 420mA to 2A. There is a minimum resistor value for RSET at lower VDD voltages. For resistor value selections, see the "Typical Characteristics: Peak
Functional Description
See "Application Information" for component selection and pre-designed circuits. Overview The MIC2145 is a 2.5W boost regulator with programmable peak current limit and a constant off time. Quiescent current for the MIC2145 is typically 200A when the switch is in the off state. Efficiencies above 80% throughout most operating conditions can be realized. Regulation Regulation is achieved by both of the comparators, which regulate the inductor current and the output voltage by gating the power MOSFET. Initially, power is applied to the SW and VDD pins. When the part is enabled, the power MOSFET turns on and current flows. When the current exceeds the peak current limit threshold, the current limit comparator fires the one-shot to turn off the power MOSFET for 1000ns and resets the SR flip-fop. The current limit comparator continues to cycle the power MOSFET on and off until the output voltage trips the upper threshold of the feedback comparator, which terminates the cycle. The cycle will begin again when the output voltage drops below the lower hysteresis threshold of the feedback comparator. The feedback comparator has a typical hysteresis of 18mV. Due to the gain of the feedback resistor divider, the voltage at VOUT experiences a typical 167mV of hysteresis for 10V output at 2.4V VDD. This can be reduced by adding a feed-forward capacitor, CFF (See "Output Voltage" section).
Current Limit vs. RSET".
Soft Start The MIC2145 has a built in soft start that controls the rise time of the output voltage and the peak current limit threshold during start up.
VEN (2V/div) VIN = 3V VOUT = 10V RSET = 10k CSS = 0.01F
VOUT (5V/div)
VSW (5V/div)
IINDUCTOR (500mA/div)
Time 200s
Figure 3. Typical Soft Start Waveforms
VOUT AC Couple (100mV/div)
Thermal Shutdown Built-in thermal protection circuitry turns off the power MOSFET when the junction temperature exceeds about 150C.
VSW (5V/div)
IINDUCTOR (500mA/div)
Time 20s
Figure 2. Typical Regulator Waveforms
May 2003
7
MIC2145
MIC2145
Micrel
A value of 1M is recommended for R1 to minimize the quiescent current when the part is off. Then, R2 can be solved using the above equation. A feed-forward capacitor, CFF, ranging from 5pF to 100pF can be used in parallel with R1 to reduce the peak-to-peak output voltage ripple, which is shown in Figures 4 and 5.
Application Information
Pre-designed circuit information is at the end of this section. Output Voltage The output voltage of the regulator can be set between 2.4V and 16V by connecting a resistor divider at the FB pin. The resistor values are selected by the following equations:
R 2=
1.08V * R1 VOUT - 1.08V
VOUT AC Couple (100mV/div)
VOUT AC Couple (100mV/div)
VSW (5V/div)
VSW (5V/div)
Time 20s
Time 4s
Figure 4. Without Feed-Forward Capacitor
Figure 5. With Feed-Forward Capacitor (100pF)
MIC2145
8
May 2003
MIC2145
Bootstrap A bootstrapped configuration is recommended for applications that require high efficiency at heavy loads (>70mA). This is achieved by connecting the VDD pin to VOUT (see
Micrel
Figure 7). For applications that require high efficiency at light loads (<70mA), the VDD pin is connected to the input voltage (VIN); this is referred to as the basic configuration (see Figure 6).
VIN 3.6V C1 10F/6.3V Murata GRM42-6 X5R 106K 6.3
L1 10H Sumida CR43-100 D1 On Semiconductor MBR0530T1 VDD EN SW R4 1M
VOUT 5V/250mA C4 10F/6.3V Murata GRM42-6 X5R 106K 6.3
PGND MIC2145 FB SGND
C3 100pF
RSET SS R1 100k R2 10k C2 0.01F
R3 274k
Figure 6. Basic Configuration
VIN 3.6V C1 10F/6.3V Murata GRM42-6 X5R 106K 6.3
L1 10H Sumida CR43-100 D1 On Semiconductor MBR0530T1 PGND SW
VOUT 5V/350mA C4 10F/6.3V Murata GRM42-6 X5R 106K 6.3
SGND VDD MIC2145 RSET SS R2 10k C2 0.01F EN R1 FB 100k R4 1M R3 274k
C3 100pF
Figure 7. Bootstrap Configuration
May 2003
9
MIC2145
MIC2145
Inductor The MIC2145 has a programmable peak current to allow the usage of small surface mount inductors. A 10H or 4.7H inductor is recommended for most portable applications such as powering white LEDs and biasing LCD panels. The
Micrel
inductor should have a saturation current rating higher than the peak current during circuit operation. A low ESR (Equivalent Series Resistance) inductor is also desirable for high efficiency. Below are tables that list the maximum output current at minimum input voltage with efficiencies greater than 80%.
VIN(min) (V)
VIN(max) (V) 4.5 9.5
RSET ()
IOUT(max) (mA) 80 25
VOUT (V) 5 10 12 15 5 10 12 15 5 10 12 15 10 12 15
VIN(min) (V)
VIN(max) (V) 4.5 9.5
RSET ( )
IOUT(max) (mA) 160 100
VOUT (V) 5 10 12 15 5 10 12 15 5 10 12 15 10 12 15
2.4 11.5 14.5 4.5 9.5 3.0 11.5 14.5 4.5 9.5 3.6 11.5 14.5 9.5 5.0 11.5 14.5
10k 20 15 150 50 10k 40 30 250 70 10k 50 40 190 10k 130 90
2.4 11.5 14.5 4.5 9.5 3.0 11.5 14.5 4.5 9.5 3.6 11.5 14.5 9.5 5.0 11.5 14.5
10k 90 70 250 150 10k 120 100 350 170 10k 150 120 300 10k 250 200
Table 1. Typical Application for 10H Inductor in Basic Configuration
Table 2. Typical Application for 10H Inductor in Bootstrap Configuration
VIN(min) (V)
VIN(max) (V) 4.5 9.5
RSET ()
IOUT(max) (mA) 250 80
VOUT (V) 5 10
VIN(min) (V)
VIN(max) (V) 4.5 4.5
RSET ()
IOUT(max) (mA) 500 225
VOUT (V) 5 10 12 15
3.0 9.5 9.5
400 60 50 12 15
3.0 4.5 4.5
200 150 130
Table 3. Typical Application for 4.7H Inductor in Basic Configuration
Table 4. Typical Application for 4.7H Inductor in Bootstrap Configuration
MIC2145
10
May 2003
MIC2145
Diode A Schottky diode should be used for the output diode. Most of the application circuits on this data sheet specify the Motorola MBR0530 surface mount Schottky diode. It has a forward current of 0.5A and a low forward voltage drop. For applications that are cost driven, the 1N4148 or equivalent can be used but the efficiency will suffer due to higher forward voltage drop. Output Capacitor Low ESR capacitors should be used at the output of the MIC2145 to minimize the switching output ripple voltage. Selection of the capacitor value will depend upon the peak inductor current, inductor size, and the load. MuRata offers the GRM43-2 series with up to 10F at 25V, with a X5R temperature coefficient in a 1812 surface-mount package. For lower output voltage applications, the GRM42-2 (1210 package/10F/16V) and GRM42-6 (1206 package/10F/ 6.3V) series can be used. Typically, values ranging from 10F to 47F can be used for the output capacitor.
Micrel
Reducing Peak Current If lower than 400mA peak current is required then the soft start pin may be shorted to ground. This changes the reference of the current limit comparator. With the soft start pin shorted to ground, the maximum current will approximately reduce to half. The peak current should always be set at least 50% higher than the maximum load current.
May 2003
11
MIC2145
MIC2145
Micrel
Pre-designed Application Circuits
VIN 3.0V-4.2V C1 10F/6.3V Murata GRM42-6 X5R 106K 6.3
L1 4.7H Murata LQH3C4R7M24 D1 On Semiconductor MBR0530T1 VDD JP1 EN SW R4 C3 1M 100pF R3 274k
VOUT 5V C4 10F/6.3V Murata GRM42-6 X5R 106K 6.3 LED1 LED2 LEDn
PGND MIC2145 FB SGND
RSET SS R1 100k R2 10k C2 0.01F
R
R
R
VIN V 3.6
VOUT V 5.0
Load mA 40
Ripple Voltage mV(peak-peak) <100
5V Output Efficiency
Efficiency % 85
90 85 EFFICIENCY (%) 80 75 70 65 VIN = 3.6V 60 1 10 100 1000 OUTPUT CURRENT (mA)
Figure 8. White LED Driver Application (Drives 1 to 10 LEDs in Parallel)
MIC2145
12
May 2003
MIC2145
Micrel
VIN 3.0V-5.0V C1 10F/6.3V Murata GRM42-6 X5R 106K 6.3
L1 10H Sumida CR32-100 D1 On Semiconductor MBR0530T1 PGND JP1 EN SW R4 1M C3 100pF
VOUT 10.0V C4 10F/16V Murata GRM42-2 X5R 106K 16
VDD MIC2145 FB SGND
RSET SS R1 100k R2 10k C2 0.01F
R3 121k
VIN V 3.0
VOUT V 10.0
Load mA 150
Ripple Voltage mV(peak-peak) <200
10V Output Efficiency
Efficiency % 83
90 85 EFFICIENCY (%) 80 75 70 65 60 10 VIN = 3.0V 100 1000 OUTPUT CURRENT (mA)
Figure 9. LCD Application -- Bootstrap Configuration
May 2003
13
MIC2145
MIC2145
Micrel
VIN 3.0V-5.0V C1 10 F/6.3V Murata GRM42-6 X5R 106K 6.3
L1 10 H Sumida CR32-100 D1 On Semiconductor MBR0530T1 PGND JP1 EN SW R4 1M C3 100pF
VOUT 15.0V
LED1 LED2 LED3 LED4
VDD MIC2145 FB SGND
C4 10 F/16V Murata GRM42-2 X5R 106K 16
R
RSET SS R1 100k R2 10k C2 0.01 F
R3 78.7k
VIN V 3.6
VOUT V 15.0
Load mA 40
Ripple Voltage mV(peak-peak) <100
Efficiency % 85
15V Output Efficiency
90 85 EFFICIENCY (%) 80 75 70 65 VIN = 3.6V 60 1 10 100 OUTPUT CURRENT (mA)
Figure 10. Series White LED Driver Application
MIC2145
14
May 2003
MIC2145
Micrel
Package Information
0.122 (3.10) 0.112 (2.84)
0.199 (5.05) 0.187 (4.74)
DIMENSIONS: INCH (MM)
0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30) R
0.007 (0.18) 0.005 (0.13)
0.012 (0.3) 0.0256 (0.65) TYP
0.008 (0.20) 0.004 (0.10)
5 MAX 0 MIN
0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53)
8-Pin MSOP (MM)
0.85 +0.15 --0.05 3.00 BSC. 1.50 BSC. 0.48 typ. 0.01 +0.04 --0.01 0.23 +0.07 --0.05 1 2 3 0.20 dia 3.00 BSC. 1
+0.15 2 1.15 --0.15
1.60 +0.15 --0.15 0.80 +0.15 --0.15 PIN 1 ID
1.50 BSC.
3
2.30 +0.15 --0.15
0.50 BSC. 0.40 +0.15 --0.05 TOP BOTTOM
SEATING PLANE TERMINAL TIP
0.23 +0.07 --0.05
0.01 +0.04 --0.01
0.50 BSC. TERMINAL TIP ODD TERMINAL SIDE
0.50 BSC.
EVEN TERMINAL SIDE
10-Pin MLF (ML)
MICREL, INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
FAX
USA
+ 1 (408) 944-0800
+ 1 (408) 944-0970
WEB
http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2003 Micrel, Incorporated.
May 2003
15
MIC2145

▲Up To Search▲

Price & Availability of MIC2145

	To Download MIC2145 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .