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.

Rating

Symbol

Value

Unit

Power Supply Voltage (Pin 7)

−0.3, 28

V

Input/Output Pins (Pins 1, 2, 3, 4, 8)

−0.3, 6.5

V

Gate Driver Output Pin (Pin 6)

−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

100

178

°C/W

Output Current, Source or Sink

1.0

A

Operating Junction Temperature Range

−40 to +150

°C

Operating Ambient Temperature Range

−25 to +105

°C

Storage Temperature Range

−55 to +150

°C

−

2.0

kV

−

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.