FEATURES

? Internal Start-Up Bias Regulator

? 3A Compound Main Gate Driver

? Programmable Line Under-Voltage Lockout

(UVLO) with Adjustable Hysteresis

? Voltage Mode Control with Feed-Forward

? Adjustable Dual Mode Over-Current Protection

? Programmable Overlap or Deadtime between

the Main and Active Clamp Outputs

? Volt x Second Clamp

? Programmable Soft-start

? Leading Edge Blanking

? Single Resistor Programmable Oscillator

? Oscillator UP / DOWN Sync Capability

? Precision 5V Reference

? Thermal Shutdown

PACKAGE

? TSSOP-16

DESCRIPTION

The LM5025C is a functional variant of the LM5025

active clamp PWM controller. The functional

differences of the LM5025C are: The maximum duty

cycle of the LM5025C is increased from 80% to 91%.

The soft-start capacitor charging current is increased

from 20 μA to 90 μA. The VCC regulator current limit

threshold is increased from 25 mA to 55 mA. The

CS1 and CS2 current limit thresholds have been

increased to 0.5V. The internal CS2 filter discharge

device has been disabled and no longer operates

each clock cycle. The internal VCC and VREF

regulators continue to operate when the line UVLO

pin is below threshold.

The LM5025C PWM controller contains all of the

features necessary to implement power converters

utilizing the Active Clamp / Reset technique. With the

active clamp technique, higher efficiencies and

greater power densities can be realized compared to

conventional catch winding or RDC clamp / reset

techniques. Two control outputs are provided, the

main power switch control (OUT_A) and the active

clamp switch control (OUT_B). The two internal

compound gate drivers parallel both MOS and Bipolar

devices, providing superior gate drive characteristics.

This controller is designed for high-speed operation

including an oscillator frequency range up to 1MHz

and total PWM and current sense propagation delays

less than 100 ns. The LM5025C includes a highvoltage

start-up regulator that operates over a wide

input range of 13V to 90V. Additional features

include: Line Under Voltage Lockout (UVLO),

softstart, oscillator UP/DOWN sync capability,

precision reference and thermal shutdown.