LT3494/LT3494A Micropower Low Noise Boost Converters with Output Disconnect FEATURESDESCRIPTION ■ Low Quiescent Current The LT®3494/LT3494A are low noise boost converters 65μA in Active Mode with integrated power switch, Schottky diode and output 1μA in Shutdown Mode disconnect circuitry. The parts use a novel* control tech- ■ Switching Frequency is Non-Audible Over Entire nique resulting in low output voltage ripple as well as high Load Range effi ciency over a wide load current range. This technique ■ Integrated Power NPN: guarantees that the switching frequency stays above the 350mA Current Limit (LT3494A) audio band for the entire load range. The parts feature a high 180mA Current Limit (LT3494) performance NPN power switch with a 350mA and 180mA ■ Integrated Schottky Diode current limit for the LT3494A and LT3494 respectively. The ■ Integrated Output Disconnect quiescent current is a low 65μA, which is further reduced ■ Integrated Output Dimming to less than 1μA in shutdown. The internal disconnect ■ Wide Input Range: 2.3V to 16V circuitry allows the output voltage to be isolated from the ■ Wide Output Range: Up to 40V input during shutdown. An auxiliary reference input (CTRL ■ Tiny 8-Lead 3mm × 2mm DFN Package pin) overrides the internal 1.225V feedback reference with any lower value allowing full control of the output voltage APPLICATIONS during operation. The LT3494/LT3494A are available in a tiny 8-lead 3mm × 2mm DFN package. ■ OLED Power ■ Low Noise Power , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ MP3 Players *Patent pending. TYPICAL APPLICATIONOutput Voltage RippleEffi ciency and Power Lossvs Load Currentvs Load CurrentOLED Power Supply from One Li-Ion Cell 15 90 280 LT3494 VIN = 3.6V LOAD FROM FIGURE 5 CIRCUIT CAPACITOR 15 80 240 V μH IN 100MHz MEASUREMENT BW 3V LOAD FROM POWER LOSS (mW) TO 4.2V 4.7μF 0.22μF 70 200 10 VOUT SW CAP VOUT 60 160 VCC VOUT 16V 16mA LT3494 2.21M 50 120 SHDN FB 2.2μF 5 EFFICIENCY (%) 40 80 CTRL GND PEAK-TO-PEAK RIPPLE (mV) 3494 TA01a OUTV 30 40 0 20 0 0.1 1 10 100 0.1 1 10 100 LOAD CURRENT (mA) LOAD CURRENT (mA) 3494 TA01c 3494 TA01b 3494fb 1
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