KA3502

www.fairchildsemi.com KA3502 PC SMPS Supervisory IC Features Complete Housekeeping Circuit Few External Components Over Voltage Protection for 3.3V/5V/12V/Adj. Output Over Current Protection for 3.3V/5V/12V Output Open-Collector Output and Remote On/Off Function Remote On/Off Delay Time Control Precision Voltage Reference for Outputs, 5V/12V Uncommitment Precision Voltage Reference for +5Vs Power Good Signal Generator with Hysteresis Disable Logic of 3.3V, 5V, 12V for Complete Shutdown Descriptions The KA3502 is complete housekeeping circuitry for use in the secondary side of SMPS(Switched Mode Power Supply). It contains various functions, which are two Precision Voltage References, Over Voltage/Current Protection, Remote On/Off Control, Power Good Signal Generator, Disable Logic and etc. 20-DIP 1 Internal Block Diagram V33 V5 V12 1 2 3 PWM FB1 VREF1 UV 14 11 6 15 VCC 5 R3 R1 R5 Vcc Adj 4 R2 R4 R6 + + + + 1.26V COMP1 Ion R8 1k R10 39k Ichg R15 5.1k 9 R9 10k R13 Vcc 5.2V + COMP9 Q3 PG Tsur 17 2.7V IS5 19 -+ 50mV IS33 20 -+ 135mV IS12 18 Vcc + COMP2 Vcc + COMP3 Vcc + - + - COMP4 65mV Vcc + 2V S Vcc Q R Q1 REFERENCE1 + COMP7 Vcc + COMP8 R12 1.28V↔1.24V 2V↔1.3V Q2 COMP5 Vcc Vcc + COMP6 1.4V Ion+ Ioff 2.8V + 2V↔0.7V R11 5.4k 12 FB2 R14 REFERENCE2 13 VREF2 R7 7 REM 8 Trem 16 GND 10 Topr Rev. 5.0 ©2000 Fairchild Semiconductor International KA3502 Pin Assignments #1 V33 #20 IS33 V5 IS5 V12 IS12 Adj Tsur VCC PWM K A 3 5 0...