1 Features

• Internal Start-Up Bias Regulator

• 3-A Compound Main Gate Driver

• Programmable Line Undervoltage Lockout (UVLO)

With Adjustable Hysteresis

• Voltage Mode Control With Feed-Forward

• Adjustable Dual-Mode Overcurrent Protection

• Programmable Overlap or Deadtime Between the

Main and Active Clamp Outputs

• Volt × Second Clamp

• Programmable Soft-Start

• Leading Edge Blanking

• Single Resistor Programmable Oscillator

• Oscillator UP and DOWN Sync Capability

• Precision 5-V Reference

• Thermal Shutdown

2 Applications

• Server Power Supplies

• 48-V Telecom Power Supplies

• 42-V Automotive Applications

• High-Efficiency DC-to-DC Power Supplies

3 Description

The LM5025 PWM controller contains all of the

features necessary to implement power converters using the active clamp and reset technique. The

device can be configured to control either a

P-channel clamp switch or an N-channel clamp

switch. With the active clamp technique, higher

efficiencies and greater power densities can be realized compared to conventional catch winding or

RDC clamp and reset techniques.

Two control outputs are provided, the main power switch control (OUT_A), and the active clamp switch

control (OUT_B). The active clamp output can be

configured for either a specified overlap time

(for P-channel switch applications) or a specified

deadtime (for N_channel applications). The two

internal compound gate drivers parallel both MOS

and bipolar devices, providing superior gate drive

characteristics. This controller is designed for highspeed

operation including an oscillator frequency

range up to 1 MHz and total PWM and current sense propagation delays less than 100 ns.

The LM5025 includes a high-voltage start-up

regulator that operates over a wide input range of

13 V to 90 V. Additional features include: line

undervoltage lockout (UVLO), soft-start, oscillator UP

and DOWN sync capability, precision reference and

thermal shutdown.