NCP1212
http://onsemi.com
4
PIN FUNCTION DESCRIPTION
Pin Name Function Description
1 FB Feedback Input This pin detects voltage feedback from output, can be connected directly to the
optocoupler collector pin.
2 BOK Brownout Detect
with Hysteresis
This is the inverting input of the brownout detect comparator. The brownout detect
comparator has a detect threshold voltage of 1.21 V. This pin senses the voltage of the
bulk capacitor through a resistor divider network to determine the brownout event. The
hysteresis band is provided by a 45 mA current flows out of this pin to the resistor
network.
3 CS Current Sense Input During output on–time of the power switch, this pin receives a voltage proportional to
power switch current set by the current sensing resistor. The information is utilized to
terminate output switch conduction by PWM action or overcurrent limit circuitry.
4 CT Programmed Oscillator
Frequency
Connecting a capacitor from CT pin to ground programs the internal oscillator frequency.
The oscillator can operate up to 200 kHz.
5 GND IC Ground −
6 DRV Gate Driver Output This is a high current totem pole output. The PWM driving control is provided by this pin.
The current and slew rate capability of this pin are suitable to drive a Power MOSFET.
7 VCC Positive Supply to IC This pin is the positive supply of the IC. The driver output gets disabled when the voltage
becomes higher than 25 V and the operating range is between 10 V and 25 V. The
startup voltage is set at 15 V.
8 SS/DMAX Soft−Start Time
Programming and
Maximum Duty Cycle
Selection
This is a multi−function pin. Soft−start effect is provided during startup with a capacitor
connected to this pin. After soft−start period elapsed, the capacitor is used for timing
control to determine output overload. If only a capacitor is connected to this pin, its final
voltage is X4.3 V and maximum turn−on duty cycle DMAX is set at 82%. Connect a
resistor in parallel with the capacitor can alter the final voltage of this pin. 48% DMAX is
selected if this pin stays at 2.1 V to 2.8 V after soft−start period.
MAXIMUM RATINGS (T
J
= 25°C unless otherwise noted.)
Rating Symbol Value Unit
Power Supply Voltage (Pin 7) V
CC
−0.3, 28 V
Input/Output Pins (Pins 1, 2, 3, 4, 8) V
IO
−0.3, 6.5 V
Gate Driver Output Pin (Pin 6) V
DRV
−0.3, 14 V
Power Dissipation and Thermal Characteristics
Thermal Resistance, Junction−to−Air, PDIP−8 Version
Thermal Resistance, Junction−to−Air, SOIC−8 Version
R
q
J−A
100
178
°C/W
Output Current, Source or Sink I
DRV
1.0 A
Operating Junction Temperature Range T
J
−40 to +150 °C
Operating Ambient Temperature Range T
A
−25 to +105 °C
Storage Temperature Range T
stg
−55 to +150 °C
ESD Capability, HBM (All pins except V
CC
pin) (Note 1) − 2.0 kV
ESD Capability, Machine Model (All pins except V
CC
pin) (Note 1) − 200 V
Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit
values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied,
damage may occur and reliability may be affected.
1. This device series contains ESD protection and exceeds the following tests:
Human Body Model (HBM) v2.0 kV per JEDEC standard: JESD22−A114.
Machine Model (MM) v200 V per JEDEC standard: JESD22−A115.
2. Latchup Current Maximum Rating: "150 mA per JEDEC standard: JESD78.
