Datasheet LT1976, LT1976B (Analog Devices) - 7

LT1976/LT1976B
W U TYPICAL PERFOR A CE CHARACTERISTICS LT1976B VC Switching Threshold vs Temperature Minimum On Time Boost Current vs Load Current
700 500 50 450 45 600 400 40 500 350 35 300 30 400 LOAD CURRENT = 0.5A 250 25 VOLTAGE (V) 300 200 20 C ON TIME (ns) LOAD CURRENT = 1A V 150 15 200 BOOST CURRENT (mA) 100 10 100 50 5 0 0 0 –50 –30 –10 10 30 50 70 90 110 –50 –30 –10 10 30 50 70 90 110 0 200 400 600 800 1000 1200 1400 TEMPERATURE (˚C) TEMPERATURE (°C) LOAD CURRENT (mA) 1976 G26 1976 G21 1976 G22
Dropout Operation Dropout Operation LT1976 Burst Mode Operation
4.0 V 6 OUT = 3.3V VOUT = 5V BOOST DIODE = DIODES INC. B1100 BOOST DIODE = DIODES INC. B1100 VOUT 3.5 50mV/DIV 5 3.0 LOAD CURRENT = 250mA 4 2.5 ISW 100mA/DIV 2.0 3 LOAD CURRENT = 1.25A LOAD CURRENT = 1.25A 1.5 LOAD CURRENT = 250mA 2 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.0 0A 1 V 0.5 IN = 12V TIME (5ms/DIV) 1976 G14 VOUT = 3.3V I 0 0 Q = 100μA 2 2.5 3 3.5 4 4.5 2 2.5 3 3.5 4 4.5 5 5.5 6 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 1976 G23 1976 G24
LT1976B No Load Operation LT1976 No Load 1A LT1976 Burst Mode Operation (Pulse-Skipping Mode) Step Response
VOUT V 50mV/DIV OUT VOUT 50mV/ AC 100mV/DIV DIV COUPLED ISW 1A ISW 100mA/DIV IOUT 100mA/ 500mA/DIV DIV 0A 0A 0A V VIN = 12V TIME (10μs/DIV) 1976 G27 V IN = 12V TIME (10μs/DIV) 1976 G15 IN = 12V TIME (1ms/DIV) 1976 G17 V VOUT = 3.3V V OUT = 3.3V OUT = 3.3V I IQ = 1.6mA C Q = 100μA OUT = 47μF 1976bfg 7