Datasheet LT1072 - 9

LT1072
U LT1072 OPERATIO Synchronizing with Bipolar Transistor Synchronizing with MOS Transistor
VIN VIN LT1072 LT1072 GND VC GND VC C2 C2 R1 D1 68pF 200pF 3k 1N4158 R3 R3 2N2369 VN2222* C1 R2 FROM 5V C1 R2 D2 FROM 5V 2.2k LOGIC 2.2k 1N4158 LOGIC *SILICONIX OR EQUIVALENT LT1072 • OP01 LT1072 • OP02
U TYPICAL APPLICATIO S Totally Isolated Converter
OPTIONAL OUTPUT FILTER L1 D1 10 1:N 15V µH + + R4 C3 C1 C5 2.7k 0.47µF N 200µF 200µF COM + + N C6 C4 L2 200µF 200µF –15V 10µH VIN VSW + V C5 IN 25 LT1072 5V µF* N = 0.875 = 7:8 FOR VOUT = 15V FB GND VC 500Ω C2 R2 0.01µF 5k *REQUIRED IF INPUT LEADS ≥ 2” ≈ 16V VIN SWITCH VOLTAGE t t OFF ON 0 VOUT + Vf (Vf = DIODE FORWARD VOLTAGE) 0V SECONDARY VOLTAGE N • VIN LT1072 • TA03 1072fc 9