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Preliminary
RT9177
Ultra-Low-Noise 200mA LDO Regulator
General Description
The RT9177 is a 200mA low dropout and low noise micro-power regulator suitable for portable RF applications. The output voltage accuracy within 2% and range from 2.4V to 3.2V in 100mV increments could be selected. It is designed for using very low ESR output capacitor. Its output remains stable even in using 1F ceramic as its output capacitor. Using an internal PMOS as the pass device cause that don't need extra GND current in heavy load and dropout conditions. In shutdown mode, nearly zero operation current cause the IC is suitable for battery-power devices. Other features including current limiting, over temperature protection and adding a capacitor in bypass pin to improve its noise performance are functional.
Features
Ultra-Low-Noise(150nV/ Hz ) for RF Application 1F Ceramic COUT Stable Low Dropout Voltage(220mV @ 200mA) Low Operation Current - 80A Typical Shutdown Function Low Temperature Coefficient Current and Thermal Limiting Custom Voltage Available SOT-25 Package
Applications
Cellular Telephones Laptop, Notebook, and Palmtop Computers Battery-powered Equipment Hand-held Equipment
Pin Configurations
Part Number RT9177CB Pin Configurations
5 4
Ordering Information
RT9177Package type B : SOT-25 Type I BR : SOT-25 Type II Operating temperature range C: Commercial standard Output voltage 24 : 2.4V 25 : 2.5V : : 31 : 3.1V 32 : 3.2V
(Plastic SOT-25)
TOP VIEW 1 2 3
1. 2. 3. 4. 5. 1. 2. 3. 4. 5.
IN GND SHDN BP OUT OUT GND IN SHDN BP
RT9177-
CBR
5
4
(Plastic SOT-25)
TOP VIEW 1 2 3
Typical Application Circuit
RT9177 VIN CIN 1F ON OFF IN GND SHDN CBP 10nF OUT COUT 1F VOUT
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RT9177
Marking Infromation
Part Number RT9177-24CB RT9177-25CB RT9177-26CB RT9177-27CB RT9177-28CB RT9177-29CB RT9177-30CB RT9177-31CB RT9177-32CB Marking H9 HA HB HC HD HE HF HG HH
Preliminary
Part Number RT9177-24CBR RT9177-25CBR RT9177-26CBR RT9177-27CBR RT9177-28CBR RT9177-29CBR RT9177-30CBR RT9177-31CBR RT9177-32CBR
Marking P9 PA PB PC PD PE PF PG PH
Pin Description
Pin Name IN GND SHDN BP OUT Pin Function IC Power Pin IC GND Active Low Shutdown Input Reference Noise Bypass Regulator Output
Function Block Diagram
SHDN
Shutdown and Logic Control VREF + _ Error Amp MOS Driver Current-Limit and Thermal Protection
IN
BP
OUT
GND
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Preliminary Absolute Maximum Ratings
Input Voltage VIN Power Dissipation SOT-25 Operating Junction Temperature Range Storage Temperature Range Thermal Resistance RJA Lead Temperature (Soldering 5 sec.)
RT9177
7V 0.25W -40C to 125C -65C to 150C 250C/W 260C
Electrical Characteristics
(VIN = 5.0V, CIN = 1F, COUT = 1F, TA = 25C, unless otherwise specified) Parameter Input Voltage Output Voltage Accuracy Maximum Output Current Current Limit GND Pin Current
(Note)
Symbol VIN VOUT IMAX ILIMIT IG IL = 1mA
Test Conditions
Min 2.5 -2 200 -------0.2 -1.0 -------
Typ ---300 80 90 1.1 55 220 -0.01 ---0.01 150 150 68
Max 6 +2 --150 150 5 100 300 +0.2 0.04 -0.4 100 1 ----
Units V % mA mA A
RLOAD = 1 Ohm No Load IOUT = 200mA IOUT = 1mA IOUT = 50mA IOUT = 200mA VIN = (VOUT+0.15) to 6V, IOUT = 1mA VIN = 3V to 5.5V VIN = 3V to 5.5V VOUT = 0V CBP = 10nF, COUT = 10F F = 100Hz, CBP = 10nF, COUT = 10F
Dropout Voltage (VOUT(Nominal)3.0V Version) Line Regulation Load Regulation SHDN Input High Threshold SHDN Input Low Threshold SHDN Bias Current Shutdown Supply Current Thermal Shutdown Temperature Output Noise Ripple Rejection
VDROP VLINE VIH VIL ISD IGSD TSD eno PSRR
mV %/V %/mA V V nA A C nV/ Hz dB
VLOAD IOUT = 0mA to 200mA
Notes: Dropout voltage definition: VIN - VOUT when VOUT is 50 mV below the value of VOUT at VIN = VOUT + 0.5V
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RT9177
Preliminary
Typical Operating Characteristics
75 74 73 72
GND Current vs. Load
0.2 0.0 -0.2
Output Voltage Variation vs. Load
TA = 25C
VOUT (%) TA = 25C
0 50 100 150 200 250
IG (uA)
71 70 69 68 67 66 65
-0.4 -0.6 -0.8 -1.0 -1.2 0 50 100
IOUT (mA)
IOUT (mA)
150
200
250
VOUT vs. VIN
3.10 3.00 250
Dropout Voltage vs. Output Current
80C Dropout Voltage (mV)
200
2.90
25C
150
VOUT (V)
2.80 2.70 2.60
20mA 50mA 100mA 200mA
100
50
VOUT = 3V TA = 25C
3.5 4.0 4.5 5.0
2.50 2.5
0 20 50 80 110 140
VOUT = 3V
170 200
3.0
VIN (V)
Output Current (mA)
Output Voltage Variation vs. Temperature
0.4 0.3 0.2 0.1 70 200mA 69 No Load 72 71
GND Current vs. Temperature
VOUT (%)
-0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -40 -10 20 80 Temperature ( C) 50 110 140
IG (uA)
0.0
68 67 66 65 64 -40 -10 20
Temperature ( C)
50
80
110
140
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Preliminary
RT9177
PSRR
PSRR
-20 -30 -40 0 -10 -20
PSRR (dB)
PSRR (dB)
-50 -60 -70 -80 -90
10mA
-30 -40 -50 -60 -70 -80 100mA 10 100 1K 10K 10mA
100mA
-100
VOUT = 3V TA = 25C CBP = 470pF
10 100 1K 10K 100K 1M
-90
VOUT = 3V TA = 25C CBP = 10nF
100K 1M
Frequency (Hz)
Frequency (Hz)
Noise Signal & Spectrum Distribution
Noise Signal (uV) Noise Signal (uV)
0 50 150 40 50 -50 30 20 10 0 0 25 2 4
Noise Signal & Spectrum Distribution
0 1 5 50 150 40 50 -50 30 20 10 0 0 25 2 4
Time (mS)
Time (mS)
6
6
8
10
8
10 150 50 -50
Noise Level (uV)
Noise Level (uV)
CIN = 1uF TAN COUT = 4.7uF TAN CBP = 10nF Load = 10mA Sampling Rate = 250KHz 125
CIN = 1uF TAN COUT = 4.7uF TAN CBP = 10nF Load = 100mA Sampling Rate = 250KHz -15 -25 -35 125
Frequency (KHz)
50
75
100
Frequency (KHz)
50
75
100
Noise Signal & Spectrum Distribution
Noise Signal (uV)
0 100 250 0 80 2 4
Noise Signal & Spectrum Distribution
10 250 0 2 4
Time (mS)
6
8
Time (mS)
6
8
10 25 0 -25
Noise Signal (uV)
100 250 80 0
0
-250 60
Noise Level (uV)
-250 CIN = 1uF TAN COUT = 4.7uF TAN CBP = 470nF Load = 10mA Sampling Rate = 250KHz -500
-250 60
40 20 0 0 25
CIN = 1uF TAN COUT = 4.7uF TAN CBP = 470nF Load = 100mA Sampling Rate = 250KHz -50 -75
Noise Level (uV)
40
20
-750
0 0 25
Frequency (KHz)
50
75
100
-100 125
Frequency (KHz)
50
75
100
-10 125
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RT9177
Load Transitne Response from 1mA to 100mA
4
Preliminary
Load Transitne Response from 100mA to 1mA
4
Output Voltage Variation (%)
3 2 1 0 -1 -2 -10
1mA Load
CIN = 1F COUT = 1F VIN = 5V TA = 25C
Output Voltage Variation (%)
100mA Load
3 2 1 0 -1 -2 -10
100mA Load 1mA Load
CIN = 1F COUT = 1F VIN = 5V TA = 25C
10
30
50
70
90
Time (uS)
10
30
50
70
90
Time (uS)
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Preliminary Application Guides
Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9177 must be carefully selected for regulator stability and performance. Using a capacitor whose value is >1F on the RT9177 input and the amount of capacitance can be increased without limit. The input capacitor must be located a distance of not more than 0.5" from the input pin of the IC and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor. The capacitor with larger value and lower ESR (equivalent series resistance) provides better PSRR and line-transient response. The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDOs application. The RT9177 is designed specifically to work with low ESR ceramic output capacitor in spacesaving and performance consideration. Using a ceramic capacitor whose value is at least 1F with ESR is > 5m on the RT9177 output ensures stability. The RT9177 still works well with output capacitor of other types due to the wide stable ESR range. Fig.1 shows the curves of allowable ESR range as a function of load current for various output voltages and capacitor values. Output capacitor of larger capacitance can reduce noise and improve loadtransient response, stability, and PSRR. The output capacitor should be located not more than 0.5" from the VOUT pin of the RT9177 and returned to a clean analog ground. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It may be necessary to use 2.2F or more to ensure stability at temperatures below -10C in this case. Also, tantalum capacitors, 2.2F or more may be needed to maintain capacitance and ESR in the stable region for strict application environment. Fig. 1
RT9177
COUT = 4.7F COUT = 1F
Tantalum capacitors maybe suffer failure due to surge current when it is connected to a low-impedance source of power (like a battery or very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed to have a surge current rating sufficient for the application by the manufacture. Use a 10nF bypass capacitor at BP for low output voltage noise. The capacitor, in conjunction with an internal 200K resistor, which connects bypass pin and the band-gap reference, creates an 80Hz lowpass filter for noise reduction. Increasing the capacitance will slightly decrease the output noise, but increase the start-up time. The capacitor connected to the bypass pin for noise reduction must have very low leakage. This capacitor leakage current causes the output voltage to decline by a proportional amount to the current due to the voltage drop on the internal 200K resistor. Fig. 2 shows the power on response.
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RT9177
T
Preliminary
Internal P-Channel Pass Transistor The RT9177 features a typical 1.1 P-channel
CB = 470pF
MOSFET
pass
transistor.
It
provides
several
CH1
1>
advantages over similar designs using PNP pass
2.2nF 10nF
transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive
CH2
2>
T T
currents under large loads. The RT9177 does not
VIN = 3.6V, CIN = 1F, COUT = 4.7F
500S/Div CH1: 2V/div; CH2 = VOUT, 500mV/div
suffer from these problems and consume only 80A of quiescent current whether in dropout, light-load, or heavy-load applications. Input-Output (Dropout) Voltage A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the RT9177 uses a Pchannel MOSFET pass transistor, the dropout voltage is a function of drain-to-source on-resistance [Rds (on)] multiplied by the load current. Reverse Current Path The power transistor used in the RT9177 has an inherent diode connected between the regulator input and output (see Fig.3). If the output is forced above the input by more than a diode-drop, this diode will become forward biased and current will flow from the VOUT terminal to VIN. This diode will also be turned on by abruptly stepping the input voltage to a value below the output voltage. To prevent regulator mis-operation, a Schottky diode should be used in any applications where input/output voltage conditions can cause the internal diode to be turned on (see Fig.4). As shown, the Schottky diode is connected in parallel with the internal parasitic diode and prevents it from being turned on by limiting the voltage drop across it to about 0.3V. < 100 mA to prevent damage to the part.
Fig. 2 Load-Transient Considerations The RT9177 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. The DC shift is quite small due to the excellent load regulation of the IC. Typical output voltage transient spike for a step change in the load current from 1mA to 100mA is tens mV, depending on the ESR of the output capacitor. Increasing the output capacitor's value and decreasing the ESR attenuates the overshoot. Shutdown Input Operation The RT9177 is shutdown by pulling the SHDN input low, and turned on by driving the input high. If this feature is not to be used, the SHDN input should be tied to VIN to keep the regulator on at all times (the SHDN input must not be left floating). To ensure proper operation, the signal source used to drive the SHDN input must be able to swing above and below the specified turn-on/turn-off voltage thresholds which guarantee an ON or OFF state (see Electrical Characteristics). The ON/OFF signal may come from either CMOS output, or an open-collector output with pull-up resistor to the RT9177 input voltage or another logic supply. The high-level voltage may exceed the RT9177 input voltage, but must remain within the absolute maximum ratings for the SHDN pin.
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Preliminary
RT9177
Current Limit and Thermal Protection The RT9177 is included a current limit circuit used to monitor and control the pass transistor's gate voltage to limit the output current to 300mA in typical and
VIN VOUT
thermal-overload protection circuit used to limit total power dissipation. When the junction temperature exceeds TJ = 150C, the thermal sensor signals the
Fig. 3
shutdown logic to turn off the pass transistor and allow the IC to cool down. The thermal sensor will turn on the pass transistor again after the IC's junction temperature cool down to 120C. This will cause a pulsing output during continuous thermal-overload conditions. Thermal-overloaded protection is designed to protect the RT9177 in the event of fault conditions. Do not exceed the absolute maximum junctiontemperature rating of TJ = 125C for continuous operation. The output can be shorted to ground for an
VIN
VOUT
Fig. 4
indefinite amount of time without damaging the part by cooperation of current limit and thermal protection.
Operating Region and Power Dissipation The maximum power dissipation of RT9177 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation across the device is P = IOUT (VIN VOUT). The maximum power dissipation is: PMAX = (TJ - TA) /ja where TJ - TA is the temperature difference between the RT9177 die junction and the surrounding environment, ja is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9177 performs the dual function of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane.
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RT9177
Package Information
Preliminary
5
D
4
C
B
1
b
3
1
A H
3
e
2
A1
L
Symbols A A1 B C D H L b e 1 2 3
Dimensions In Millimeters Min 1.000 0.000 1.400 2.600 2.700 0.100 0.300 0.300 -2 5 -Typ 1.100 -1.600 2.800 2.900 0.150 0.450 0.400 0.950 ---Max 1.300 0.100 1.800 3.000 3.100 0.250 0.600 0.500 -8 10 10 Min 0.039 -0.055 0.102 0.106 0.004 0.012 0.012 -----
Dimensions In Inches Typ 0.043 -0.063 0.110 0.114 0.006 0.018 0.016 0.037 ---Max 0.051 0.004 0.071 0.118 0.122 0.010 0.024 0.020 -----
5-Lead SOT- 25 Surface Mount Package
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Preliminary
RT9177
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RT9177
RichTek Technology Corp.
Headquarter
6F, No. 35, Hsintai Road, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749
RichTek Technology Corp.
Taipei Office (Marketing)
4F-1, No. 127, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek-ic.com.tw
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