NCP1000, NCP1001, NCP1002
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2
FUNCTIONAL PIN DESCRIPTION
Pin Function Description
1 V
CC
Positive input supply voltage. This pin is connected to an external capacitor for energy storage.
The startup circuit sources current out of this pin to initially charge the capacitor. When the
voltage reaches the upper threshold limit of the undervoltage lockout circuit, the startup circuit
will turn off, and the power supply will begin operation. Power is then supplied to the chip via
this pin, by virtue of the auxiliary winding.
2 Feedback Input
The error signal from the optocoupler is fed into this input. It is loaded with a 2.7 kΩ resistor
which converts the opto current into a voltage. There is a 7.0 kHz, single pole, low pass filter
between this pin and the error amp input. A 10 volt clamp is also connected to this pin to protect
the device from ESD damage or overvoltage conditions.
3, 6, 7, 8 Ground Ground reference pin for the circuit. These pins are part of the integrated circuit leadframe and
are an integral part of t he heat flow path on the PDIP--8 package.
4 Startup This pin is connected to the bulk DC input voltage supply. It feeds an internal current source that
initially charges up the V
CC
capacitor on power up.
5 Power Switch Circuit The internal power switch circuit is connected between this pin and ground. This pin connects
directly to one end of the transformer primary winding.
MAXIMUM RATINGS (Notes 1 and 2)
Rating Symbol Value Unit
Power Switch Circuit (Pin 5)
Drain Voltage Range
Drain Current Peak During Transformer Saturation
V
DS
I
DS(pk)
−0.3 to 700
2.0 I
lim
Max
V
A
Power Supply Voltage Range (Pin 1) V
clp
−0.3to10 V
Feedback Input (Pin 2)
Voltage Range
Current
V
I(fb)
l
fb
−0.3to10
100
V
mA
Thermal Resistance
P Suffix, Plastic P ackage Case 626
Junction--to--Lead
Junction--to--Air, 2.0 Oz. Printed Circuit Copper Clad
0.36 Sq. Inch
1.0 Sq. Inch
R
θ
JL
R
θ
JA
5.0
45
35
C/W
Operating Junction Temperature T
J
−40 to 125 C
Storage Temperature T
stg
−65 to +150 C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to s tresses above the Recommended Operating Conditions may affect
device reliability.
1. This device series contains ESD protection and exceeds the following tests:
Pins 1--3: Human Body Model 2000 V per MIL--STD--883, Method 3015.
Machine Model Method 200 V.
Pins 4 and 5 are the HV startup and the drain of the LDMOS device, rated only to the max rating of the part , or 700 V.
2. This device contains Latchup protection and exceeds ±200 mA per JEDEC Standard JESD78.
