NCP1651
http://onsemi.com
2
PIN FUNCTION DESCRIPTION
Pin No.
Function
Description
1
Output
Drive output for power FET or IGBT. Capable of driving small devices, or can be connected to an
external driver for larger transistors.
2
Ground
Ground reference for the circuit.
3
C
T
Timing capacitor for the internal oscillator. This capacitor adjusts the oscillator frequency.
4
Ramp
Compensation
This pin biases the ramp compensation circuit, to adjust the amount of compensation that is added to
the current signal for stability purposes.
5
I
S+
Positive current sense input. Designed to connect to the positive side of the current shunt.
6
I
avg- -fltr
A capacitor connected to this pin filters the high frequency component from the instantaneous current
waveform, to create a waveform that resembles the average line current.
7
I
avg
An external resistor with a low temperature coefficient is connected from this terminal to ground, to set
and stabilize the gain of the Current Sense Amplifier output that drives the AC error amplifier.
8
Feedback/
Shutdown
The error signal from the error amplifier circuit is fed via an optocoupler or other isolation circuit, to this
pin. A shutdown circuit is also connected to this pin which will put the unit into a low power shutdown
mode if this voltage is reduced to less than 0.6 volts.
9
AC Input
The fullwave rectified sinewave input is connected to this pin. This information is used for the reference
comparator and the average current compensation circuit.
10
AC Reference
A capacitor is connected to this pin to filter the modulated output of the reference multiplier.
11
AC
Compensation
Provides pole for the AC Reference Amplifier. This amplifier compares the sum of the AC input voltage
and the low frequency component of the input current to the reference signal. The response must be
slow enough to filter out most of the high frequency content of the current signal that is injected from the
current sense amplifier, but fast enough to cause minimal distortion to the line frequency information.
12
Vref
6.5 volt regulated reference output.
13
V
CC
Provides power to the device. This pin is monitored for undervoltage and the unit will not operate if the
V
CC
voltage is not within the UVLO range. Initial power is supplied to this pin via the high voltage startup
network.
14
No Connection
This pin is not available due to spacing considerations of the startup pin.
15
No Connection
This pin is not available due to spacing considerations of the startup pin.
16
Startup
This pin connects to the rectified input signal and provides current to the internal bias circuitry for the
startup period of operation.
NOTE: Pins 14 and 15 have not been used for clearance considerations due to the potential voltages present on pin 16. In order to
maintain proper spacing between the high voltage and low voltage pins, traces should not be placed on the circuit board between
pins 16 and 13.