LM5026 Datasheet, PDF (1/23 Pages) National Semiconductor (TI) – Active Clamp Current Mode PWM Controller

August 2005
LM5026
Active Clamp Current Mode PWM Controller
General Description
The LM5026 PWM controller contains all of the features
necessary to implement power converters utilizing the active
clamp / reset technique with current mode control. 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
device can be configured to control either a P-Channel or
N-Channel clamp switch. The main gate driver features a
compound configuration, consisting of both MOS
and Bipolar devices, providing superior gate drive character-
istics. The LM5026 can be configured to operate with bias
voltages over a wide input range of 8V to 100V. Additional
features include programmable maximum duty cycle, line
under-voltage lockout, cycle-by-cycle current limit, hiccup
mode fault operation with adjustable timeout delay, PWM
slope compensation, soft-start, 1MHz capable oscillator with
synchronization input / output capability, precision reference
and thermal shutdown.
Features
n Current Mode Control
n Internal 100V Start-up Bias Regulator
n 3A Compound Main Gate Driver
n High Bandwidth Opto-coupler Interface
n Programmable Line Under-Voltage Lockout (UVLO) with
Adjustable Hysteresis
n Versatile Dual Mode Over-Current Protection with hiccup
delay timer
n Programmable Overlap or Deadtime between the Main
and Active Clamp Outputs
n Programmable Maximum Duty Cycle Clamp
n Programmable Soft-start
n Leading Edge Blanking
n Resistor Programmed 1MHz Capable Oscillator
n Oscillator Sync I/O Capability
n Precision 5V Reference
Packages
n TSSOP-16
n LLP-16 (5x5 mm) Thermally Enhanced (Available
Soon)
Typical Application Circuit
Simplified Forward Power Converter with Active Clamp Reset
20147901
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