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.