UC3846 Ver la hoja de datos (PDF) - Fairchild Semiconductor

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Fabricante

UC3846

SMPS Controller

Fairchild Semiconductor 

UC3846

SMPS Controller

www.fairchildsemi.com

Features

• Automatic Feed Forward Compensation

• Programmable Pulse by Pulse Current Limiting

• Automatic Symmetry Correction in Push-Pull

Configuration

• Enhanced Load Response Characteristics

• Parallel Operation Capability for Modulator Power

Systems

• Differential Current Sense Amplifier with Common Mode

Range

• Double Pulse Suppression

• 200mA Totem-Pole Outputs

• ±2% Band gap Reference

• Under-Voltage Lockout

• Soft-Start Capability

• Shutdown Terminal

• 500KHz Operation

Description

The UC3846 control IC provides all of the necessary fea-

tures to implement fixed frequency, current mode control

schemes while maintaining a minimum external parts count.

The superior performance of this technique can be measured

in improved line regulation, enhanced load response char-

acteristics, and a simpler, easier-to-design control loop.

Topological advantages include inherent pulse-by-pulse cur-

rent limiting capability, automatic symmetry correction for

push-pull converters, and the ability to parallel “power

module,, while maintaining equal current sharing. Protection

circuitry includes built-in-under-voltage lockout and pro-

grammable current limit in addition to soft-start capability. A

shutdown function is also available which can initiate either

a complete shutdown with automatic restart or latch the

supply off. Other features include fully latched operation,

double pulse suppression, deadtime adjust capability, and

±2% trimmed bandgap reference. The UC3846 features low

outputs in the OFF state.

16-DIP

1

Internal Block Diagram

10

©2000 Fairchild Semiconductor International

Rev. 5.0

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