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RT9168/A
200mA/500mA Fixed Output Voltage LDO Regulator
General Description
The RT9168/A is a 200mA/500mA low dropout and micropower regulator suitable for portable applications. The output voltages range from 1.5V to 5.0V in 100mV increments and 2% accuracy. The RT9168/A is designed for use with very low ESR capacitors. The output remains stable even with a 1F ceramic output capacitor. The RT9168/A uses an internal PMOS as the pass device, which does not cause extra GND current in heavy load and dropout conditions. The shutdown mode of nearly zero operation current makes the IC suitable for batterypowered devices. Other features include current limiting and over temperature protection. The SOT-23-5 and SOP-8 packages are also available for larger power dissipation and design flexibility.
Features
Stable with Low-ESR Output Capacitor Low Dropout Voltage (220mV at 200mA) Low Operation Current -80A Typical Shutdown Function Low Temperature Coefficient Current and Thermal Limiting Custom Voltage Available SOT-23-5 and SOP-8 Packages RoHS Compliant and 100% Lead (Pb)-Free
Applications
Cellular Telephones Laptop, Notebook, and Palmtop Computers Battery-powered Equipment Hand-held Equipment
Ordering Information
RT9168/A Package Type BR : SOT-23-5 S : SOP-8 SH : SOP-8, High Shutdown Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) Output Voltage 15 : 1.5V 16 : 1.6V : : 49 : 4.9V 50 : 5.0V 500mA Output Current 200mA Output Current
Marking Information
For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail.
Pin Configurations
(TOP VIEW)
VOUT GND VIN 1 2 3 4 EN 5 NC
RT9168/ACBR SOT-23-5
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.
VOUT GND GND NC 2 3 4
8 7 6 5
VIN GND GND EN/EN
RT9168/ART9168/ASOP-8
CS CSH
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RT9168/A
Typical Application Circuit
RT9168/A VIN CIN 1uF VIN GND EN/EN NC VOUT COUT 1uF VOUT
+ +
Functional Pin Description
Pin Name VIN GND EN (EN) NC VOUT Pin Function Input Voltage Ground Chip Enable Active High (Low) No Connection Output Voltage
Function Block Diagram
EN/EN
Shutdown and Logic Control VREF
+ Error Amplifier
VIN
MOS Driver VOUT Current-Limit and Thermal Protection R1
R2
GND
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RT9168/A
Absolute Maximum Ratings
Input Voltage ------------------------------------------------------------------------------------------------------------ 8V Power Dissipation, PD @ TA = 25C SOT-23-5 ---------------------------------------------------------------------------------------------------------------- 0.4W SOP-8 -------------------------------------------------------------------------------------------------------------------- 0.625W Package Thermal Resistance (Note1) SOT-23-5, JA ----------------------------------------------------------------------------------------------------------- 250C/W SOP-8, JA -------------------------------------------------------------------------------------------------------------- 160C/W Operating Junction Temperature Range -------------------------------------------------------------------------- -40C to 125C Storage Temperature Range ---------------------------------------------------------------------------------------- -65C to 150C Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260C
Electrical Characteristics
(VIN = 5.0V, CIN = 1F, COUT = 1F, TA = 25C, unless otherwise specified)
Parameter Input Voltage Range Output Voltage Accuracy Maximum Output Current Current Limit RT9168 RT9168A RT9168 RT9168A RT9168/A GND Pin Current RT9168 RT9168A RT9168/A Dropout Voltage RT9168/A (VOUT(Nominal)3.0V RT9168/A Version) RT9168A Line Regulation Load Regulation RT9168/A RT9168A EN, EN Input High Threshold EN, EN Input Low Threshold EN, EN Bias Current Shutdown Supply Current Thermal Shutdown Temperature Ripple Rejection
(2)
Symbol VIN VOUT IMAX
Test Conditions
Min 2.9
Typ -----300 700 80 90 90 1.1 55 220 600 -0.01 0.01 ---0.01 155 58
Max Units 7 7 +2 ----150 150 150 5 100 300 750 +0.2 0.04 0.04 -0.4 100 1 --V V nA A C dB mV mV mV mV %/V %/mA A % mA mA mA mA V
IL = 50mA IL = 1mA
2.7 -2 200 500 --
ILIM
RLOAD = 1 No Load
---------0.2 --2.2 ---
IG
IOUT = 200mA IOUT = 500mA IOUT = 1mA
VDROP
IOUT = 50mA IOUT = 200mA IOUT = 500mA
VLINE VLOAD VIH VIL ISD IGSD TSD PSRR
VIN = (VOUT+0.15) to 7V, IOUT = 1mA IOUT = 0mA to 200mA IOUT = 0mA to 500mA V IN = 3V to 5.5V V IN = 3V to 5.5V
VOUT = 0V
---
F = 100Hz, CBP = 10nF, COUT = 10F
--
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RT9168/A
Note 1. 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 2. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV.
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RT9168/A
Typical Operating Characteristics
Output Voltage vs. Temperature
3.33 3.32
GND Current vs. Temperature
120 105
GND Current (uA)1
VOUT = 3.3V
Output Voltage (V)
3.31 3.30 3.29 3.28 3.27 3.26 3.25 -50 -25 0 25 50 75 100 125 150
90 75 60 45 30 15
VOUT = 3.3V
0 -50 -25 0 25 50 75 100 125 150
Temperature (C)
Temperature (C)
Dropout Voltage vs. Output Current
300 250
Current Limit vs. Temperature
480 420
Dropout Voltage (mV)
85C
200 150 100 50
Current Limit (mA)
360 300 240 180 120 60
25C -40C
VOUT = 3.3V
0 0 25 50 75 100 125 150 175 200
RT9168 VOUT = 3.3V
-50 -25 0 25 50 75 100 125 150
0
Output Current (mA)
Temperature (C)
Current Limit vs. Temperature
900 800
PSRR
70 60 50
Current Limit (mA)
700 600 500 400 300 200 100 -50 -25 0 25 50 75 100 125 150
PSRR (dB)
40 30 20
RT9168A VOUT = 3.3V
10 0
VOUT = 3.3V, ILOAD = 1mA COUT = 4.7V 10 10 100 100 1K 1000 10K 10000 100K 100000 1M 1000000
Temperature (C)
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Frequency (kHz)
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RT9168/A
Load Transient Response
60
Load Transient Response
60
Output Voltage Deviation (mV)
40 20 0 -20
Output Voltage Deviation (mV)
CIN = 10uF COUT = 1uF
VIN = 4V VOUT = 3.0V
40 20 0 -20
CIN = 10uF COUT = 4.7uF
VIN = 4V VOUT = 3.0V
Load Current (mA)
50 1 -50
Load Current (mA)
50 1 -50
Time (50us/Div)
Time (50us/Div)
Line Transient Response
150
Line Transient Response
150
Output Voltage Deviation (mV)
100 50 0 -50
Output Voltage Deviation (mV)
VOUT = 3.0V COUT = 1uF
Loading = 1mA
100 50 0 -50
VOUT = 3.0V COUT = 1uF
Loading = 50mA
Input Voltage Deviation(V)
5 4
Input Voltage Deviation(V)
5 4
Time (1ms/Div)
Time (1ms/Div)
Line Transient Response
Output Voltage Deviation (mV) Output Voltage Deviation (mV)
VOUT = 3.0V 100 COUT = 4.7uF 50 0 -50 150 Loading = 1mA 60 40 20 0 -20
Line Transient Response
VOUT = 3.0V COUT = 4.7uF Loading = 50mA
Input Voltage Deviation(V)
5 4
Input Voltage Deviation(V)
5 4
Time (500us/Div)
Time (500us/Div)
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RT9168/A
Application Information
Region of Stable Cout ESR v.s Load Current
Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9168/A must be carefully selected for regulator stability and performance. Using a capacitor whose value is > 1F on the RT9168/A input and the amount of capacitance can be increased without limit. The input capacitor must be located 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 linetransient response. The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDO applications. The RT9168/A 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 RT9168/A output ensures stability. The RT9168/A still works well with output capacitor of other types due to the wide stable ESR range. Figure 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 load-transient response, stability, and PSRR. The output capacitor should be located not more than 0.5" from the VOUT pin of the RT9168/A 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.
100
Unstable Region
10
COUT = 4.7uF COUT = 1uF
Stable Region
Cout ESR ( )1
1
0.1
0.01
Unstable Region
0.001 0 40 80 120 160 200
Load Current (mA)
Figure 1 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. Load-Transient Considerations The RT9168/A 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 0mA to 50mA 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 RT9168/A is shutdown by pulling the EN input low, and turned on by driving the input high. If this feature is not to be used, the EN input should be tied to VIN to keep the regulator on at all times (the EN input must not be left floating).
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RT9168/A
To ensure proper operation, the signal source used to drive the EN 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 RT9168/A input voltage or another logic supply. The highlevel voltage may exceed the RT9168/A input voltage, but must remain within the absolute maximum ratings for the EN pin. Internal P-Channel Pass Transistor The RT9168/A features a typical 1.1 P-channel MOSFET pass transistor. It provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current considerably. PNPbased regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The RT9168/A does not suffer from these problems and consume only 80A of quiescent current whether in dropout, light-load, or heavyload 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 RT9168/A uses a P-channel MOSFET pass transistor, the dropout voltage is a function of drain-to-source onresistance [RDS(ON)] multiplied by the load current. Reverse Current Path The power transistor used in the RT9168/A has an inherent diode connected between the regulator input and output (see Figure 2). 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 Figure Figure 2 3). 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.
VIN
VOUT
VIN
VOUT
Figure 3 Current Limit and Thermal Protection The RT9168 includes a current limit which monitors and controls the pass transistor's gate voltage limiting the output current to 300mA Typ. (700mA Typ. for RT9168A). Thermal-overload protection limits total power dissipation in the RT9168/A. When the junction temperature exceeds TJ = +155C, the thermal sensor signals the shutdown logic turning off the pass transistor and allowing the IC to cool. The thermal sensor will turn the pass transistor on again after the IC's junction temperature cools by 10C, resulting in a pulsed output during continuous thermaloverload conditions. Thermal-overloaded protection is designed to protect the RT9168/A in the event of fault conditions. Do not exceed the absolute maximum junction-temperature rating of TJ = +150C for continuous operation. The output can be shorted to ground for an indefinite amount of time without damaging the part by cooperation of current limit and thermal protection.
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RT9168/A
Operating Region and Power Dissipation The maximum power dissipation of RT9168/A 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 RT9168/A die junction and the surrounding environment, JA is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9168/A 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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RT9168/A
Outline Dimension
H D L C B
b A A1 e
Symbol A A1 B b C D e H L
Dimensions In Millimeters Min 0.889 0.000 1.397 0.356 2.591 2.692 0.838 0.080 0.300 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610
Dimensions In Inches Min 0.035 0.000 0.055 0.014 0.102 0.106 0.033 0.003 0.012 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024
SOT-23-5 Surface Mount Package
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RT9168/A
A
H M
J
B
F
C I D
Dimensions In Millimeters Symbol Min A B C D F H I J M 4.801 3.810 1.346 0.330 1.194 0.170 0.050 5.791 0.400 Max 5.004 3.988 1.753 0.508 1.346 0.254 0.254 6.200 1.270
Dimensions In Inches Min 0.189 0.150 0.053 0.013 0.047 0.007 0.002 0.228 0.016 Max 0.197 0.157 0.069 0.020 0.053 0.010 0.010 0.244 0.050
8-Lead SOP Plastic 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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