LM5026_09 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Active Clamp Current Mode PWM Controller

January 15, 2009
LM5026
Active Clamp Current Mode PWM Controller
General Description
The LM5026 PWM controller contains all of the features nec-
essary 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 con-
figured to control either a P-Channel or N-Channel clamp
switch. The main gate driver features a compound configu-
ration, consisting of both MOS and Bipolar devices, providing
superior gate drive characteristics. The LM5026 can be con-
figured 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-cy-
cle current limit, hiccup mode fault operation with adjustable
timeout delay, PWM slope compensation, soft-start, 1MHz
capable oscillator with synchronization input / output capabil-
ity, precision reference and thermal shutdown.
Features
■ ^{Current Mode Control}
■ ^{Internal 100V Start-up Bias Regulator}
■ ^{3A Compound Main Gate Driver}
■ ^{High Bandwidth Opto-coupler Interface}
■ ^{Programmable Line Under-Voltage Lockout (UVLO) with}
Adjustable Hysteresis
■ ^{Versatile Dual Mode Over-Current Protection with hiccup}
delay timer
■ ^{Programmable Overlap or Deadtime between the Main}
and Active Clamp Outputs
■ ^{Programmable Maximum Duty Cycle Clamp}
■ ^{Programmable Soft-start}
■ ^{Leading Edge Blanking}
■ ^{Resistor Programmed 1MHz Capable Oscillator}
■ ^{Oscillator Sync I/O Capability}
■ ^{Precision 5V Reference}
Packages
■ ^TSSOP-16
■ ^{LLP-16 (5x5 mm) Thermally Enhanced}
Typical Application Circuit
Simplified Forward Power Converter with Active Clamp Reset
20147901
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