NCP1212(2004) Просмотр технического описания (PDF) - ON Semiconductor

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производитель

NCP1212
(Rev.:2004)

Current Mode PWM Controller for Both Forward and Flyback Converters

ON Semiconductor 

NCP1212

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ PIN FUNCTION DESCRIPTION

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Pin Name

Function

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ 1

FB

Feedback Input

Description

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 Connecting a capacitor from CT pin to ground programs the internal oscillator frequency.

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.

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ MAXIMUM RATINGS (TJ = 25°C unless otherwise noted.)

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Rating

ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Power Supply Voltage (Pin 7)

Symbol

VCC

Value

Unit

−0.3, 28

V

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

VIO

−0.3, 6.5

V

Gate Driver Output Pin (Pin 6)

VDRV

−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

RqJ−A

°C/W

100

178

Output Current, Source or Sink

IDRV

1.0

A

Operating Junction Temperature Range

TJ

−40 to +150

°C

Operating Ambient Temperature Range

TA

−25 to +105

°C

Storage Temperature Range

Tstg

−55 to +150

°C

ESD Capability, HBM (All pins except VCC pin) (Note 1)

−

2.0

kV

ESD Capability, Machine Model (All pins except VCC 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.

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