L1923

UNISONIC TECHNOLOGIES CO., LTD L1923 Preliminary CMOS IC 500mA HIGH PSRR LDO REGULATORS DESCRIPTION The UTC L1923 is a low supply current, low dropout linear regulator. It is operating at 2.5V - 5.5V. The supply current is as low as 55μA in the no–load condition. In the shutdown mode, the maximum supply current is less than 1μA. A built-in over-temperature protection circuit is designed to protect the device from being damaged by thermal overload. The over-current protection limit is set at 800mA (TYP.) The UTC L1923 can be operated on the following two modes. When the SET pin is connected to ground, the output of L1923 is a pre-set value and the external components are not needed to decide the output voltage. When an output other than the preset value is needed, two external resistors should be used as voltage dividers and then the output voltage is decided by the resistor ratio. The UTC L1923 is generally used in notebook computers, cellular phones, PDAs, digital still camera and video recorders and other hand-held devices. 4 5 2 3 1 SOT-25 FEATURES * Low No-Load Supply Current: 90µA * Guaranteed 500mA Output Current * Dropout Voltage is 200mV @ 250mA Load *OTP(Over-Temperature Protection) and Short-Circuit Protection * Two Modes Of Operation: Fixed Mode：3.3V，3.5V，3.9V Adjustable Mode: 1.25V - 5.5V * Maximum Supply Current In Shutdown Mode is Less than 1µA * Low Output Noise at 238µVRMS * Stability with Lost Cost Ceramic Capacitors ORDERING INFORMATION Ordering Number Package L1923G-xx-AF5-R SOT-25 xx: Output Voltage, refer to Marking Information. L1923G-xx-AF5-R (1)Packing Type (2)Package Type (3)Output Voltage Code (4)Halogen Free Packing Tape Reel Note: (1) R: Tape Reel (2) AF5: SOT-25 (3) xx: Refer to Marking Information (4) G: Halogen Free www.unisonic.com.tw Copyright © 2010 Unisonic Technologies Co., Ltd 1 of 7 QW-R502-440.b L1923 MARKING INFORMATION PACKAGE VOLTAGE CODE 33:3.3V SOT-25 35:3.5V 39:3.9V Preliminary CMOS IC MARKING PIN CONFIGURATION SHDN 1 5 SET GND 2 IN 3 4 OUT PIN DESCRIPTION PIN NO. 1 2 3 4 5 PIN NAME SHDN GND IN OUT SET DESCRIPTION Active-Low Shutdown Input. A logic low reduces the supply current to less than 1µA. Connect to IN for normal operation. Ground. This pin also functions as a heatsink. Solder to large pads or the circuit board ground plane to maximize thermal dissipation. Regulator Input. Supply voltage can range from +2.5V to +5.5V. Bypass with 1µF to GND Regulator Output. Fixed or adjustable from 1.25V to +5.5V. Sources up to 500mA. Bypass with a 4.7µF, ＜0.2Ω typical ESR capacitor to GND. Feedback Input for Setting the Output Voltage. Connect to GND to set the output voltage to the preset output voltage. Connect to an external resistor divider for adjustable-output operation. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 7 QW-R502-440.b L1923 BLOCK DIAGRAM Preliminary CMOS IC UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 7 QW-R502-440.b L1923 ABSOLUTE MAXIMUM RATING Preliminary CMOS IC PARAMETER SYMBOL RATINGS UNIT VIN to GND -0.3~7 V Output Short-Circuit Duration Infinite SET to GND -0.3~7 V SHDN to GND -0.3~7 V SHDN to IN -7~0.3 V OUT to GND -0.3~(VIN+0.3) V Continuous Power Dissipation (TA=25°C) 520 mW PD Junction Temperature 150 °C TJ Operating Temperature -40~85 °C TOPR Storage Temperature -65~160 °C TSTG Notes: Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. THERMAL DATA PARAMETER Junction to Ambient SYMBOL θJA RATINGS 240 UNIT °C/W ELECTRICAL CHARACTERISTICS (VIN =+3.6V, VSHDN =VIN, TA =TJ =+25°C, unless otherwise specified.) (Note 1) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Input Voltage (Note 2) VIN 2.5 5.5 V Output Voltage Accuracy VOUT Variation from specified VOUT, IOUT=1mA -2 2 % Adjustable Output Voltage VOUT VSET 5.5 V Range (Note 3) Maximum Output Current 500 mA Current Limit (Note 4) ILIMIT 600 800 mA Short Circuit Current Isc 120 mA Ground Pin Current IQ 90 120 µA I =250mA 200 mV Dropout Voltage (Note 5) VDROP OUT 400 500 IOUT=500mA SET=GND, VIN=V(STD)+0.1V ~ 5.5V , Line Regulation ΔVLNR 0.06 0.12 %/V IOUT=10mA Load Regulation ΔVLDR IOUT= 10mA ~500mA 0.02 0.1 %/mA Ripple Rejection PSRR F=100Hz, 0.45VP-P, IOUT=10mA 65 dB F≤100kHz, IOUT =0A 136 µV Output Noise Noise F≤100kHz, IOUT =250mA 238 (RMS) F≤100kHz, IOUT =500mA 253 SHUTDOWN VIH Regulator enabled 1.5 SHDN Input Threshold V VIL Regulator shutdown 0.4 SHDN Input Bias Current ISHDN VSHDN= VIN TA= +25°C 0.003 0.1 µA Shutdown Supply Current IQSHDN VOUT= 0V TA= +25°C 0.2 1 µA SET INPUT TA= +25°C 1.225 1.25 1.275 VIN= 2.5V ~ 5.5V, V SET Reference Voltage (Note 3) VSET IOUT= 1mA 1.25 TA= TMIN to TMAX SET Input Leakage Current ISET VSET= 1.3V TA= +25°C 5 30 nA (Note 3) THERMAL PROTECTION Thermal Shutdown Temperature TSHDN 145 °C Thermal Shutdown Hysteresis ΔTSHDN 25 °C Notes: 1.Limits is 100% production tested at TA= +25°C. Low duty pulse techniques are used during test to maintain junction temperature as close to ambient as possible. 2.Guaranteed by line regulation test. 3.Adjustable mode only. 4.Not tested. For design purposes, the current limit should be considered 600mA minimum to 800mA maximum. 5.The dropout voltage is defined as (VIN-VOUT) when VOUT is 100mV below the target value of VOUT. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 4 of 7 QW-R502-440.b L1923 APPLICATION INFORMATION Preliminary CMOS IC The UTC L1923 contains an error amplifier, 1.25V bandgap reference, PMOS output transistor, internal feedback voltage divider, mode comparator, shutdown logic, over current protection circuit, and over temperature protection circuit as shown in the block diagram. The process of operation is like this: the mode comparator compares the voltage of SET pin with a pre-set voltage reference of 0.35V. If the voltage of SET pin is smaller than 0.35V, the internal feedback voltage divider’s central tap is connected to the error amplifier’s non-inverting input. Then, the error amplifier compares non-inverting input with the 1.25V bandgap voltage reference. If the feedback voltage is larger than the voltage reference 1.25V, the error amplifier’s output becomes higher. This makes the PMOS output transistor’s VGS (gate-to-source voltage) smaller, in that condition, the current carrying capability of the PMOS output transistor is reduced, as a result the output voltage decreases until the feedback voltage becomes equal to 1.25V. Similarly, when the feedback voltage is less than 1.25V, the error amplifier causes the output PMOS to conductor more current to pull the feedback voltage up to 1.25V. Thus, through this feedback action, the error amplifier, output PMOS, and the voltage dividers effectively form a unity-gain amplifier with the feedback voltage force to be the same as the 1.25V bandgap reference. The output voltage, VOUT, can be calculated as follows: VOUT = 1.25 (1 + R1/R2). (1) Alternatively, the relationship between R1 and R2 is expressed in the following: R1 = R2 (VOUT /1.25 - 1). (2) In order to reduce power dissipation and loop stability, it is recommended that R2 is 100KΩ. For UTC L1923-330, R1 is 164K, and the pre-set VOUT is 3.30V. In Figure 2, the SET pin voltage will be larger than 350mV when external voltage divider functions in the operation. The non-inverting input of the amplifier will be connected to the external voltage divider. The conditions of equations 1 and 2 are still true since the operation of the feedback loop is the same. Equation 1 still presents the output voltage. Over Current Protection To monitor the output current, the UTC L1923 applies a current mirror. A portion of the PMOS output transistor’s current is mirrored to a resistor such that the voltage across this resistor is proportional to the output current. Once the output current exceeds limit threshold, UTC L1923 would be protected with a limited output current. Further more, when the output is short to ground, the output current would be folded-back to a less limit. Over Temperature Protection Over-temperature protection circuit is designed to prevent this device from being damaged due to abnormal temperature during operation. It is used to turn off the output MOSFET if the temperature is higher than 145°C, the switch does not turn on until the temperature drops to 120°C. Shutdown Mode The UTC L1923 enters shutdown mode if the SHDN pin is applied to a logic low voltage. Under the shutdown state, all the analog circuits are turned off completely, which reduces the current consumption to only the leakage current. The UTC L1923 output pass transistor would get into high impedance level. There is an internal discharge path to help to shorten discharge delay time. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 5 of 7 QW-R502-440.b L1923 Preliminary CMOS IC APPLICATION INFORMATION (Cont.) Operating Region and Power Dissipation The UTC L1923 is a linear regulator, so the power dissipation can be expressed by: P = IOUT (VIN – VOUT). And the maximum power dissipation is calculated by: PD(MAX) = (TJ–TA)/θJA,=(150°C -25°C)/240°C/W= 520mW (Where (TJ–TA) is the temperature difference the die and the ambient air; θJA, is the thermal resistance of the chosen package to the ambient air.) For surface mount device, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. The die attachment area of the UTC L1923’s lead frame is connected to pin 2, which is the GND pin. Therefore, the GND pin of UTC L1923 can carry away the heat of the UTC L1923 die very effectively. Connecting the GND pin to ground using a large ground plane near the GND pin can improve the power consumption. Capacitor Selection and Regulator Stability A 1µF capacitor on the input and a 4.7µF capacitor on the output are recommended for most applications of the U TC L1923. To get a better supply-noise rejection and transient response, input capacitors with larger values and lower ESR are needed. A higher-value input capacitor (10µF) may be necessary if large, fast transients are anticipated and the device is located several inches from the power source. Power-Supply Rejection and Operation from Sources Other than Batteries The UTC L1923 is particularly designed to deliver low dropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is 42dB at low frequencies. As the frequency increases above 20kHz, the output capacitor is the major contributor to the rejection of power-supply noise. When operating from sources other than batteries, improve supply-noise rejection and transient response by increasing the values of the input and output capacitors, and using passive filtering techniques. Input-Output (Dropout) Voltage The minimum input-output voltage differential (or dropout voltage) of a regulator determines the lowest usable supply voltage. In battery-powered system applications, this will determine the useful end-of-life battery voltage. Because the UTC L1923 use a P-channel MOSFET pass transistor, their dropout voltage is a function of RDS(ON) multiplied by the load current. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 7 QW-R502-440.b L1923 Preliminary CMOS IC TYPICAL APPLICATION CIRCUIT SHDN UTC L1923 IN + BATTERY CIN 1µ GND SET OUT COUT 4.7µ OUTPUT Fixed Mode SHDN UTC L1923 IN + BATTERY CIN 1µ GND OUT R1 SET R2 OUTPUT COUT 4.7µ Adjustable Mode UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 7 QW-R502-440.b