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463_ver temperature protection

By Tom Smith,2014-10-14 16:40
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463_ver temperature protection

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     Preliminary

     RT9167/A

     Low-Noise, Fixed Output Voltage, 300mA/500mA LDO Regulator

     General Description

     The RT9167/A is a 300mA/500mA low dropout and low noise micropower regulator suitable for portable applications. The output voltages range from 1.5V to 5.0V in 100mV increments and 2% accuracy. The RT9167/A is designed for use with very low ESR capacitors. The output remains stable even with 1?ÌF ceramic output capacitor. The RT9167/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 battery-powered devices. Other features include a reference bypass pin to improve low noise performance, current limiting, and over temperature protection.

     Features

     Stable with Low-ESR Output Capacitor Low Dropout Voltage (350mV @ 300mA) Low Operation Current - 80?ÌA Typical ?Ì Shutdown Function Low Noise Output Low Temperature Coefficient Current and Thermal Limiting Custom Voltage Available SOT-25 and SOP-8 Packages

     Applications

     Cellular Telephones Laptop, Notebook, and Palmtop Computers Battery-powered Equipment Hand-held Equipment

     Ordering Information

     RT9167/A-

     Pin Configurations

     Package Type B : SOT-25 BR : SOT-25 R Type S : SOP-8 Operating Temperature Range C : Commercial Standard P : Pb Free with Commercial Standard Optput Voltage 15 : 1.5V 16 : 1.6V : 49 : 4.9V 50 : 5.0V 2H : 2.85V 500mA Output Current 300mA Output Current

     (TOP VIEW)

     VIN GND SHDN 1 2 3 4 BP 5 VOUT

     SOT-25

     VOUT GND VIN 1 2 3 4 SHDN 5 BP

     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.

     SHDN VIN VOUT BP

     SOT-25 (R-Type)

     8 2 3 4 7 6 5 GND GND GND GND

     SOP-8

     DS9167/A-17 March 2004

     www.richtek.com 1

     RT9167/A

     Functional Pin Description

     Pin Name VIN GND SHDN BP VOUT Pin Function Input Voltage Ground Active Low Shutdown Input Reference Noise Bypass Output Voltage

     Preliminary

     Function Block Diagram

     SHDN VREF BP + MOS Driver

     Error Amplifier

     Shutdown and Logic Control

     VIN

     -

     Current-Limit and Thermal Protection

     VOUT R1 R2

     GND

     Typical Application Circuit

     RT9167/A VIN CIN 1uF VIN GND SHDN

     OFF

     VOUT

     COUT 1uF

     VOUT

     +

     +

     ON

     BP

     CBP 10nF

     www.richtek.com 2

     DS9167/A-17 March 2004

     Preliminary Absolute Maximum Ratings

     RT9167/A

     Input Voltage

    ---------------------------------------------------------------------------------------------------------- 8V Power Dissipation, PD @ TA = 25?ãC SOT-25

    ----------------------------------------------------------------------------------------------------------------- 0.25W SOP-8 ------------------------------------------------------------------------------------------------------------------ 0.625W Operating Junction Temperature Range

    ------------------------------------------------------------------------- ?40?ã C to 125?ã C Storage Temperature Range ------------------------------------------------------------------

    --------------------- ?65?ã C to 150?ã C Package Thermal Resistance SOT-25, ?ÈJA

    ------------------------------------------------------------------------------------------------------------ 250?ã C/W SOP-8, ?ÈJA ------------------------------------------------------------------------------------------- 160?ã C/W Lead Temperature (Soldering, 5 sec.)

    --------------------------------------------------------------------------- 260?ãC

     Electrical Characteristics

     (VIN = 5.0V, CIN = 1?ÌF, COUT = 1?ÌF, TA = 25?ãC, unless otherwise specified)

     Parameter Input Voltage Range Output Voltage Accuracy Maximum Output Current Current Limit RT9167 RT9167A RT9167 RT9167A RT9167/A Quiescent Current

     Symbol VIN ?VOUT

     Test Conditions

     Min 2.9 2.7 -2 300 500 400 500 ----------1.6 -----

     Typ ------700 80 90 90 1.1 55 350 600 ------0.01 155 350 58

     Max 7 7 +2 ----150 150 150 5 100 450 750 6 30 35 -0.4 100 1 ----

     Units V % mA mA

     IL = 50mA IL = 1mA

     IMAX

     ILIMIT RLOAD = 1? No Load IOUT = 300mA IOUT = 500mA IOUT = 1mA VDROP IOUT = 50mA IOUT = 300mA IOUT = 500mA ?VLINE VIN= (VOUT+0.15) to 7V, IOUT =1mA IOUT = 0mA to 300mA IOUT = 0mA to 500mA VIN= 3V to 5.5V VIN = 3V to 5.5V

     RT9167/A IG RT9167A RT9167/A RT9167/A RT9167/A RT9167A

     ?ÌA

     Dropout Voltage (VOUT(Normal) = 3.0V Version) Line Regulation Load Regulation

     (Note)

     mV

     mV/V mV V V nA ?ÌA ?ãC nV Hz dB

     RT9167/A RT9167A

     VLOAD VIH VIL ISD

     SHDN Input High Threshold SHDN Input Low Threshold SHDN Bias Current Shutdown Supply Current Thermal Shutdown Temperature Output Noise Ripple Rejection

     IGSD

     TSD eNO PSRR

     VOUT = 0V

     CBP = 10nF, COUT = 10?ÌF F = 100Hz, CBP = 10nF, COUT = 10?ÌF

     ---

     Note: Dropout voltage definition: VIN - VOUT when VOUT is 50 mV below

    the value of VOUT at VIN = VOUT + 0.5V DS9167/A-17 March 2004

    www.richtek.com 3

     RT9167/A

     3.33 3.32

     Preliminary

     Typical Operating Characteristics

     Output Voltage vs. Temperature

     120 105

     Quiescent Current vs. Temperature

     Quiescent Current (uA) 1

     Output Voltage (V)

     3.31 3.30 3.29 3.28 3.27 3.26

     90 75 60 45 30 15

     VOUT = 3.3V

     3.25 -50 -25 0 25 50 75 100 125 150

     VOUT = 3.3V

     0 -50 -25 0 25 50 75 100 125 150

     Temperature (?ã C)

     Temperature (?ã C)

     Dropout Voltage vs. Load Current

     250

     Dropout Voltage vs. Load Current

     600

     125?ãC

     Dropout Voltage (mV)

     200

     Dropout Voltage (mV)

     125?ãC 25?ãC

     150

     500

     25?ãC

     400 300 200 100 0

     100

     -40?ãC

     -40?ãC

     50

     RT9167 VOUT = 5.0V

     RT9167A VOUT = 3.3V

     0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

     0 0 0.05 0.1 0.15 0.2 0.25 0.3

     Load Current (A)

     Load Current (A)

     Current Limit vs. Temperature

     700 650

     900 800

     Current Limit vs. Temperature

     Current Limit (mA)

     Current Limit (mA)

     RT9167 VOUT = 5.0V

     600 550 500 450 400 350 300 -50 -25 0 25 50 75 100 125

     700 600 500 400 300 200 -50 -25 0 25 50 75 100 125

     RT9167A VOUT = 3.3V

     Temperature (?ã C)

     Temperature (?ã C)

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     DS9167/A-17 March 2004

     Preliminary

     RT9167/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 CBP = 10nF

     VIN = 4V VOUT = 3.0V

     40 20 0 -20

     CIN = 10uF COUT = 4.7uF CBP = 10nF

     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 CBP = 10nF

     Loading = 1mA

     100 50 0 -50

     VOUT = 3.0V COUT = 1uF CBP = 10nF

     Loading = 50mA

     Input Voltage Deviation (V)

     5 4

     Input Voltage Deviation (V)

    

    

    

     5 4

    

     Time (1ms/Div)

     Time (1ms/Div)

     Line Transient Response

     150

     Line Transient Response

     60

     Output Voltage Deviation (mV)

     100 50 0 -50

     Output Voltage Deviation (mV)

     VOUT = 3.0V COUT = 4.7uF CBP = 10nF

     Loading = 1mA

     40 20 0 -20

     VOUT = 3.0V COUT = 4.7uF CBP = 10nF

     Loading = 50mA

     Input Voltage Deviation (V)

     5 4

     Input Voltage Deviation (V)

    

    

    

     5 4

    

     Time (500us/Div)

     Time (500us/Div)

     DS9167/A-17 March 2004

     www.richtek.com 5

     RT9167/A

     70 60

     Preliminary

     PSRR

     Region of Stable COUT ESR vs. Load Current

     100.00 100

     Unstable Region

     10.00 10

     COUT = 1uF

     Stable Region

     COUT ESR (?)

     50

     PSRR (dB)

     40 30 20 10 0

     1.001

     0.1 0.10 Unstable Region

     0.01 0.01

     VOUT = 3.3V, ILOAD = 1mA COUT = 4.7uF, CBP = 10nF 10 10 100 100 1K 1000 10K 10000 100K 100000 1M 1000000 0.001 0.00

     0 50 100 150 200 250 300

     Frequency (kHz)

     Load Current (mA)

     Figure 1

     Application Information

     Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9167/A must be carefully selected for regulator stability and performance. Using a capacitor whose value is > 1?ÌF on the RT9167/A 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 RT9167/A is designed specifically to work with low ESR ceramic output capacitor in space-saving and performance consideration. Using a ceramic capacitor whose value is at least 1?ÌF with ESR is > 5m? on the RT9167/A output ensures stability. The RT9167/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 loadtransient response, stability, and PSRR. The output

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     capacitor should be located not more than 0.5" from the VOUT pin of the RT9167/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 2.2?ÌF or more to ensure

    stability at temperatures below -10?ãC in this case. Also, tantalum capacitors, 2.2?ÌF or more may be needed to maintain capacitance and ESR in the stable region for strict application environment. 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 low-pass 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. Figure 2 shows the power on response.

     DS9167/A-17 March 2004

     Preliminary

     CBP == 1nF CBP 10nF

     RT9167/A

     Internal P-Channel Pass Transistor The RT9167/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 RT9167/A does not suffer from these problems and consume only 80?ÌA 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 RT9167/ A uses a P-channel 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 RT9167/A has an inherent diode connected between the regulator input and output (see Figure 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 Figure 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.

     Voltage (0.5V/Div) Voltage (0.5V / DIV)

     CBP == 10nF BP 10nF

     VOUT = 3.0V VOUT=3.0V 0 0

     5.0

     10.0

     15.0 15.0

     Time (ms) Time (ms)

     Figure 2 Load-Transient Considerations The RT9167/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 RT9167/A 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 pullup resistor to the RT9167/A input voltage or another logic supply. The high-level voltage may exceed the RT9167/ A input voltage, but must remain within the absolute maximum ratings for the SHDN pin.

     DS9167/A-17 March 2004

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     RT9167/A

     Preliminary

     Current Limit and Thermal Protection

     VIN

     VOUT

     Figure 3

     VIN

     VOUT

     Figure 4 Operating Region and Power Dissipation The maximum power dissipation of RT9167/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) /?ÈJA where TJ - TA is the temperature difference between the RT9167/A die junction and the surrounding environment, ?ÈJA is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9167/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.

     T9167 includes a current limit which monitors and controls the pass transistor's gate voltage limiting the output current to 350mA Typ. (700mA Typ. for RT9167A). Thermaloverload protection limits total power dissipation in the RT9167/A. When the junction temperature exceeds TJ = +155?ã C, 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 10?ãC, resulting in a pulsed output during continuous thermaloverload conditions. Thermal-overloaded protection is designed to protect the RT9167/A in the event of fault conditions. Do not exceed the absolute maximum junctiontemperature rating of T J = +150?ãC 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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     DS9167/A-17 March 2004

     Preliminary Outline Dimension

     H D L C B

     RT9167/A

     b A A1 e

     Symbol A A1 B b C D e H L

     Dimensions In Min 0.889 0.000 1.397 0.356 2.591 2.692 0.838 0.102 0.356 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 0.004 0.014 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024

     SOT- 25 Surface Mount Package

     DS9167/A-17 March 2004

     www.richtek.com 9

     RT9167/A

     Preliminary

     A

     H M

     J

     B

     F

     C I D

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