KA3502 Просмотр технического описания (PDF) - Fairchild Semiconductor
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KA3502 Datasheet PDF : 14 Pages
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KA3502
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Pin Name
V33
V5
V12
ADJ
VCC
PWM
REM
Trem
PG
Topr
UV
FB2
VREF2
VREF1
FB1
GND
Tsur
IS12
IS5
IS33
Pin Function Descrition
+3.3 V Output Voltage of SMPS Secondary side
+5 V Output Voltage of SMPS Secondary side
+12 V Output Voltage of SMPS Secondary side
Adjustable OVP Input. Its Threshold Voltage is 1.26 V. This pin can be used for
another
protection signal.
Supply Voltage. Operating range is 15 V ~ 24 V. Vcc=18 V, Ta=25°C at test.
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.
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.
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.
Power Good output signal. PG="High" means that the power is "Good" for operation
and PG="Low" means "Power Fail".
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.
Under-Voltage Detect Pin. Its threshold voltage is 1.26V ± 20mV Typ.
Feedback for Precision Reference2. Absolute min/max current rating is 1 mA/30 mA.
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%.
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%.
Feedback for Precision Reference1. Absolute min/max current rating is 2 mA/30 mA
because of
internal connection.
Ground
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.
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.
Current Sense Input for +5 V. The OCP Offset voltage for +5 V is 50 mV
Current Sense Input for +3.3 V. The OCP Offset voltage for +3.3 V is 135 mV
3
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