2000 Fairchild Semiconductor International
www.fairchildsemi.com
Rev. 5.0
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.
Internal Block Diagram
4
17
19
20
18
1
2
3
6 15
14 11
5
9
12
13
10
16
8
7
+
+
+
+
-
Vcc
R5
R1
R3
R6
R2
R4
COMP1
1.26V
Adj
Tsur
IS5
IS33
IS12
2.7V
Vcc
COMP2
Vcc
COMP3
Vcc
COMP4
+
-
+
-
+
-
+
-
+
-
+
-
135mV
65mV
50mV
Vcc
Vcc
+
-
2V
COMP5
COMP6
1.4V
+
-
R
S Vcc
Q
Ion
2.8V
Ion+
Ioff
Vcc
+
-
2V
0.7V
Q1
REFERENCE1
R8
1k
R9
10k
R10
39k
R13
R11
5.4k
R12
R14
1.28V
1.24V
+
-
+
-
Vcc
Vcc
COMP8
COMP7
Q2
5.2V
Ichg
2V
1.3V
Q3
+
-
R15
5.1k
COMP9
PG
VREF2
REFERENCE2
FB2
Topr
GND
Trem
REM
V33 V5 V12
PWM FB1 VREF1 UV
VCC
R7
KA3502
PC SMPS Supervisory IC
20-DIP
1
KA3502
2
Pin Assignments
NO
NAME
FUNCTION
NO
NAME
FUNCTION
1
V33
+3.3 V OUTPUT VOLTAGE
11
UV
PG INPUT for Det
2
V5
+5 V OUTPUT VOLTAGE
12
FB2
FEEDBACK for REFERENCE 2
3
V12
+12 V OUTPUT VOLTAGE
13
VREF2
PRECISION REFERENCE
4
Adj
ADJUSTABLE OVP INPUT
14
VREF1
PRECISION REFERENCE
5
VCC
SUPPLY VOLTAGE
15
FB1
FEEDBACK for REFERENCE 1
6
PWM
REMOTE ON/OFF OUTPUT
16
GND
GROUND
7
REM
REMOTE ON/OFF INPUT
17
Tsur
OCP DELAY
8
Trem
REMOTE ON/OFF DELAY
18
IS12
Current INPUT for +12V
9
PG
POWER GOOD OUTPUT
19
IS5
Current INPUT for +5V
10
Topr
PG DELAY
20
IS33
Current INPUT for +3.3V
#1
V33
V5
V12
Adj
VCC
PWM
REM
Trem
PG
Topr
#10
#20
IS33
IS5
IS12
Tsur
GND
FB1
VREF1
VREF2
FB2
UV
#11
K
A
3
5
0
2
KA3502
3
Pin Description
Pin Number
Pin Name
Pin Function Descrition
1
V33
+3.3 V Output Voltage of SMPS Secondary side
2
V5
+5 V Output Voltage of SMPS Secondary side
3
V12
+12 V Output Voltage of SMPS Secondary side
4
ADJ
Adjustable OVP Input. Its Threshold Voltage is 1.26 V. This pin can be used for
another
protection signal.
5
VCC
Supply Voltage. Operating range is 15 V ~ 24 V. Vcc=18 V, Ta=25
C at test.
6
PWM
Remote On/Off Output. This signal controls the primary power switch (PWM IC)
through an Opto-coupler.
Maximum current rating is 30 mA. When PWM="Low", the main SMPS is operational
and If PWM="High", the main SMPS is turned-off.
7
REM
Remote On/Off Input. It is TTL operation and its threshold voltage is 1.4 V. Voltage at
this pin can reach normally 4.6 V, with absolutely maximum voltage, 5.25 V. If
REM="Low", PWM="Low". That means the main SMPS is operational. When REM
="High", then PWM="High" and the main SMPS is turned-off.
8
Trem
Remote On/Off delay. Ton/Toff=8 ms/24 ms (Typ.) with Ctrem=0.1uF. Its High/Low
threshold voltage is 2 V/0.7 V and the maximum voltage after full charging is about
2.8 V. So,
V (Chg.) = 2 V,
V (Dischg.) = 2.1 V Typ.
9
PG
Power Good output signal. PG="High" means that the power is "Good" for operation
and PG="Low" means "Power Fail".
10
Topr
PG Delay. Td=250 ms (Typ.) with Ctopr=2.2uF. The High/Low threshold voltage are
2 V/1.3 V and the voltage of PIN 10 is clamped at 5.2 V for Noise margin.
11
UV
Under-Voltage Detect Pin. Its threshold voltage is 1.26V
20mV Typ.
12
FB2
Feedback for Precision Reference2. Absolute min/max current rating is 1 mA/30 mA.
13
VREF2
Precision Reference 2 input Voltage. This circuit equals to KA431 and it is designed
for an Auxiliary voltage,
+5 Vs. It is trimmed to
1.6%.
14
VREF1
Precision Reference 1 Input Voltage. This circuit equals to KA431 and it is for
corrective output voltages of +5 V/+12 V. It's trimmed to
1.6%.
15
FB1
Feedback for Precision Reference1. Absolute min/max current rating is 2 mA/30 mA
because of
internal connection.
16
GND
Ground
17
Tsur
Timing pin for Over Current Protection blank-out time. Its threshold voltage is 2 V and
clamped at 2.7 V after full charging. Target of delay time is 20 ms~30 ms and it is
realized through external R & C.
18
IS12
Current Sense Input for +12V. This pin is connected to the Current Sensing resistor
or inductor. If the voltage drop of the resistor or inductor is larger than the fixed offset
voltage ( 65 mV Typ.), PWM becomes "High" after some delay and the main SMPS
is turned-off.
19
IS5
Current Sense Input for +5 V. The OCP Offset voltage for +5 V is 50 mV
20
IS33
Current Sense Input for +3.3 V. The OCP Offset voltage for +3.3 V is 135 mV
KA3502
4
Absolute Maximum Ratings
Temperature Characteristics
Parameter
Symbol
Value
Unit
Supply Voltage
Vcc
15 ~ 24
V
UV Input Voltage
Vuv
24
V
Input Maximum Voltage
Vin (max)
Vcc - 3
V
Cathode Current for FB1, 2
Ik1, 2
1 ~ 30
mA
PWM Maximum Current
Io (PWM)
30
mA
PG Output Maximum Current
Io (PG)
30
mA
Power Dissipation
Pd
1
W
Operating Temperature Range
Topr
0 ~ 70
C
Storage Temperature Range
Tstg
-65 ~ 150
C
Parameter
Symbol
Value
Unit
Temperature Stability for Vref1, 2
(0
C
Ta
70
C)
Vref1, 2
17
mV
KA3502
5
Electrical Characteristics (Vcc = 18V, Ta = 25
C)
Parameter
Symbol
Condition
Min.
Typ.
Max.
Unit
PROTECTION SECTION
Over Voltage Protection For 3.3 V
Vovp33
Pin 7 (REM)=0V
3.8
4.0
4.2
V
Over Voltage Protection For 5 V
Vovp5
Pin 7 (REM)=0V
5.8
6.1
6.4
V
Over Voltage Protection For 12 V
Vovp12
Pin 7 (REM)=0V
13.4
14.2
15.0
V
OVP Input Threshold Voltage for Adj
Vadj
Pin 7 (REM)=0V
1.22
1.26
1.30
V
Comparator Offset Voltage for 3.3 V
Vos33
Pin 7 (REM)=0V
125.5
135
144.5
mV
Comparator Offset Voltage for 5 V
Vos5
Pin 7 (REM)=0V
46.5
50
53.5
mV
Comparator Offset Voltage for 12 V
Vos12
Pin 7 (REM)=0V
60.5
65
69.5
mV
OCP Delay Comparator Input
Threshold Voltage
Vth (Tsur)
Pin 7 (REM)=0V
1.9
2
2.1
V
Pin 17 (Tsur) Input Clamp Voltage
V17max
Pin 7 (REM)=0V
-
2.7
4
V
REMOTE ON/OFF SECTION
Remote On/off Input Threshold Vtg.
Vth
Pin 7 (REM): "L"
"H"
1
-
1.8
V
Remote On/off Input Open Voltage
Vih
Pin 7 Open
4
-
5.25
V
Remote On/off Input Low Current
Iil
Pin 7 (REM)=0 V
0
-
-1.0
mA
ON Delay Time
Ton
REM: "L"
"H", C=0.1 uF
4
8
14
msec
OFF Delay Time
Toff
REM: "L"
"H", C=0.1 uF
16
24
34
msec
PWM Saturation Voltage
Vsat
(PWM)
Io=0.5 mA
-
-
1.3
V
PWM Leakage Current
Ileak
Pin 6 (PWM)=20 V
-
0.01
1
uA
REFERENCE 1 SECTION
Reference Input Voltage 1
Vref1
IIk1=1 mA
2.46
2.50
2.54
V
Line Regulation 1
Vref1 (line) 15 V<Vcc<20 V
-
1
-
mV/V
Current Stability 1
Vref1
Ik1=1 mA to 10 mA
-
5
20
mV
Output Sinking Current Capability 1
Isink1
-
15
25
-
mA
Absolute Precision of Internal Three
Resistors
Rint
-
-
15
-
%
Matching Coefficient of Internal Three
Resistors
Rrate
-
-
1
-
%
Temperature Stability
Vref1
Ta=0 to 70
C (Note 1)
-
13
17
mV
Gain Bandwidth 1
GBW1
GV=1 (Note 1)
-
1
-
MHz
KA3502
6
Electrical Characteristics (Continued)
Note:
1.These parameters, although guaranteed, but not 100% tested in production.
Parameter
Symbol
Condition
Min.
Typ.
Max.
Unit
REFERENCE 2 SECTION
Reference Input Voltage 2
Vref2
IIk2=1 mA
2.46
2.50
2.54
V
Line Regulation 2
Vref2 (line) 15 V<Vcc<20 V
-
1
-
mV/V
Current Stability 2
Vref2
Ik2 mA to 10 mA
-
5
20
mV
Output Sinking Current Capability 2
Isink2
-
15
25
-
mA
Temperature Stability 2
Vref2
Ta=0 to 70
C (Note 1)
-
13
17
mV
Gain Bandwidth 2
GBW2
GV=1 (Note 1)
-
1
-
MHz
POWER GOOD SECTION
Detecting UV Voltage
Vuv
Pin 7 (REM)=0V
1.22
1.26
1.30
V
Detecting V5 Voltage
Vin (V5)
Pin 7 (REM)=0V
4.1
4.3
4.5
V
Hysteresis Voltage 1
HY1
Pin 11 (UV): "L"
"H"
20
40
80
mV
Hysteresis Voltage 2
HY2
Pin 10 (Topr): "L"
"H"
0.2
0.7
-
V
High Threshold Voltage of Comp 9
Vth (H)
Pin 10 (Topr): "L"
"H"
1.8
2.0
2.2
V
Noise margin of Vtopr
Vtopr
Vtopr (max) - Vth (L)
2
4
-
V
Charging Current for PG Delay
Ichg
Pin 10 (Topr)=GND
-12
-18
-28
uA
Turn-On Delay Time for PG
Topr
Ctopr=2.2uF
100
250
500
msec
UV Input Pull Down Resistor
Ruv
-
-
20
-
kohm
PG Output Rising Time
Tr
C=0.1nF (Note 1)
-
1
-
usec
PG Output Falling Time
Tf
C=0.1nF (Note 1)
-
300
-
nsec
PG Output Saturation Voltage
Vsat (PG)
Isink=15 mA
-
0.3
0.4
V
PG Output Voltage at High Status
Vpgh
Isource=100 uA
4.2
-
5.25
V
DISABLE SECTION
Disable Saturation Voltage for V33
Vdis33
REM=2 V, Isink=10 mA
-
0.2
0.4
V
Disable Saturation Voltage for V5
Vdi5
REM=2 V, Isink=10 mA
-
0.2
0.4
V
Disable Saturation Voltage for V12
Vdis12
REM=2 V, Isink=10 mA
-
0.2
0.4
V
TOTAL STANDBY CURRENT
Supply Current Of Vcc
Icc
Vcc=18 V, REM=2V
-
5
10
mA
KA3502
7
Typical Characteristics
2.510
2.505
2.500
2.495
2.490
-25
0
25
50
75
100
Temp (Dgree)
Vr
e
f
(
V
)
2.53
2.52
2.51
2.50
2.49
0
5
10
15
20
25
30
1k (mA)
V
r
ef
1,
2 (V
)
20
15
10
5
0
1.10
1.15
1.20
1.25
1.30
1.35
Vadj (V)
PW
M (V
)
5.0
5.5
6.0
6.5
7.0
V5 (V)
20
15
10
5
0
PWM
(
V
)
3.50
3.75
4.00
4.25
4.50
V33 (V)
20
15
10
5
0
PWM
(
V
)
-25
0
25
50
75
100
Temp (Degree)
1.260
1.255
1.250
1.245
1.240
Va
d
j
(
V
)
Figure 1. Temperature Stability for Vref1,2
Figure 2. Vref1,2 Current Stability
Figure 3. Bandgap Voltage (Vadj)
Figure 4. OVP Input Threshold Voltage for Adj
Figure 3. Over Voltage Protection for +3.3V
Figure 4. OCP Offiset Voltage for 3.3V
KA3502
8
Typical Characteristics (Continued)
20
15
10
5
0
PW
M
(V
)
110
120
130
140
150
Vos33 (mV)
20
15
10
5
0
PWM
(
V
)
55
60
65
70
75
V8 (V)
0.0
0.5
1.0
1.5
2.0
2.5
V8 (V)
20
15
10
5
0
PWM
(V
)
0.0
0.5
1.0
1.5
2.0
Vth (V)
20
15
10
5
0
PW
M (V
)
40
45
50
55
60
Vos5 (mV)
20
15
10
5
0
PW
M (V
)
12
13
14
15
16
V12 (V)
20
15
10
5
0
PWM (
V
)
Vos33=IS33-V33
Vos=IS12-Vo12
Vos5=IS5-V5
Figure 7. Over Voltage Protection for +12V
Figure 8. OCP Offiset Voltage for 3.3V
Figure 9. OCP Offiset Voltage for 5V
Figure 10. OCP Offiset Voltage for 12V
Figure 11. Remotr On/Off Input Threshold
Figure 12. ON/OFF Delay Threshold Voltage
KA3502
9
Typical Characteristics (Continued)
1.20
1.22
1.24
1.26
1.28
1.30
Vuv (V)
6
5
4
3
2
1
0
PG
(
V
)
0.5
1.0
1.5
2.0
2.5
V10 (V)
5
4
3
2
1
0
PG
(
V
)
0
5
10
15
20
Isink (mA)
0.4
0.3
0.2
0.1
0.0
Vd
i
s
(
V
)
0
5
10
15
20
25
Isink (mA)
0.4
0.3
0.2
0.1
0.0
V
s
at
_P
G (
V
)
5.0
4.8
4.6
4.4
4.2
4.0
V5 (V)
5
4
3
2
1
0
PG
(V
)
0
5
10
15
20
Isink (mA)
25
20
15
10
5
0
PWM
(
V
)
Figure 13. PWM Saturation Voltage
Figure 14. Detecting UV Voltage
Figure 15. Detecting V5 Voltage for PG
Figure 17. PG Saturating Voltage
Figure 16. High/low Threshold Voltage of Comp9
Figure 18. Disable Saturation Voltage
KA3502
10
Typical Characteristics (Continued)
14
16
18
20
22
Vcc (V)
10
8
6
4
2
0
I
cc (m
A)
0.0
0.2
0.4
0.6
0.8
1.0
Time (sec)
6
5
4
3
2
1
0
(V
)
0
20
40
60
80
100
Time (msec)
20
15
10
5
0
(V
)
PG
UV
PWM
REM
24
Figure 19. Supply Current of Vcc
Figure 20.
Figure 21. PG Delay
KA3502
11
Mechanical Dimensions
Package
Dimensions in millimeters
20-DIP
KA3502
12
Ordering Information
Product Number
Package
Operating Temperature
KA3502
20-DIP
0
C ~ 70
C
KA3502
13
KA3502
9/25/00 0.0m 001
Stock#DSxxxxxxxx
2000 Fairchild Semiconductor International
LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
INTERNATIONAL. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER
DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
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