LM5025A Datasheet, PDF (1/23 Pages) National Semiconductor (TI) – Active Clamp Voltage Mode PWM Controller

LM5025A
www.ti.com
SNVS293E – DECEMBER 2004 – REVISED MARCH 2013
Active Clamp Voltage Mode PWM Controller
Check for Samples: LM5025A
FEATURES
1
•2 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
PACKAGES
• TSSOP-16
• WSON-16 (5x5 mm) Thermally Enhanced
DESCRIPTION
The LM5025A is a functional variant of the LM5025
active clamp PWM controller. The functional
differences of the LM5025A are: 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 V_CC and V_REF regulators continue to
operate when the line UVLO pin is below threshold.
The LM5025A 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 100ns. The LM5025A includes a high-
voltage 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.
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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