Datasheet LT1072 - 10

LT1072
U TYPICAL APPLICATIO S Flyback Converter
CLAMP TURN-ON L2 V SPIKE 10 SNUB µH C4 V 200µF a PRIMARY FLYBACK VOLTAGE = OUT + Vf V N OPTIONAL IN LT1072 SWITCH VOLTAGE b FILTER AREA “a” = AREA “b” TO MAINTAIN 0V D1 V ZERO DC VOLTS ACROSS PRIMARY V OUT + Vf OUT VIN 5V 20 TO 30V 1.5A c N • V SECONDARY VOLTAGE R4 C3 1 N* IN ** 0V AREA “c” = AREA “d” TO MAINTAIN 1k 0.47µF + 1 C1 d ZERO DC VOLTS ACROSS SECONDARY N* = 3 500µF ∆I IPRI D2 V R1 IN VSW 3.74k PRIMARY CURRENT 0 + C4 LT1072 25µF* IPRI SECONDARY CURRENT N 0 I FB PRI GND VC LT1070 SWITCH CURRENT R3 R2 0 I 1.5k 1.24k PRI C2 0.15µF SNUBBER DIODE CURRENT 0 *REQUIRED IF INPUT LEADS ≥ 2" (IPRI) (LL) **OPTIONAL TO REPLACE R4 AND C3 t = VSNUB LT1072 • TA04
Negative to Positive Buck-Boost Converter External Current Limit
L2 VIN V OPTIONAL SW L1** C3 OUTPUT 220µH FILTER LT1072 D1 V V OUT IN + FB VSW 12V, 0.5A V V GND C R1 IN + C2 – 11.3k + C4 LT1072 1000µF 25µF* Q1 R1 R2 OPTIONAL FB 1k INPUT GND VC Q1 FILTER C2 C1 R3 R2 1000pF L3 2.2k 1.24k NOTE THAT THE LT1072 GND PIN C1 *REQUIRED IF INPUT LEADS ≥ 2" IS NO LONGER COMMON TO V V 0.22µF R IN (–) IN S **PULSE ENGINEERING 52626 –12V LT1072 • TA06 LT1072 • TA05 1072fc 10