KA3502 Datasheet, PDF (1/14 Pages) Fairchild Semiconductor – PC SMPS Supervisory IC

KA3502
PC SMPS Supervisory IC
www.fairchildsemi.com
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 Volt-
age 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
123
PWM FB1 VREF1 UV
VCC
6 15 14 11
5
Adj 4
Vcc
+
+
+
+
- ^COMP1
1.26V
Tsur 17
IS5 19
IS33 20
IS12 18
2.7V
-+
50mV
Vcc
+
-
COMP2
Vcc
-+
135mV
+
-
COMP3
Vcc
+
-+ - _COMP4
65mV
Vcc
+
- _COMP5
2V
Vcc
+
-
COMP6
1.4V
R7
7
REM
Ion
S ^Vcc
Q
R
2.8V
Ion+
Ioff
R8
R10
1k
39k
Vcc
+
-
2V↔0.7V
R9
R13
5.2V
10k
Vcc
+ COMP7
-
Q1
Vcc
REFERENCE1
+
-
COMP8
R11
5.4k
R12
1.28V↔1.24V
R14
Ichg
R15
5.1k
9
PG
+
Q3
-
COMP9
2V↔1.3V
Q2
12
FB2
13
REFERENCE2
VREF2
8
16
10
Trem
GND
Topr
©2000 Fairchild Semiconductor International
Rev. 5.0