LM5026_14 Datasheet, PDF (1/31 Pages) Texas Instruments – Active Clamp Current Mode PWM Controller

LM5026
www.ti.com
SNVS363C – AUGUST 2005 – REVISED MARCH 2010
LM5026 Active Clamp Current Mode PWM Controller
Check for Samples: LM5026
FEATURES
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•2 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
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 characteristics. 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.
Packages
• TSSOP-16
• 5x5 mm Thermally Enhanced
Typical Application Circuit
V_IN
36 - 78V
V_OUT
3.3V
T1
CS
V_CC
V_IN
LM5026
CS
UVLO _{OUT_A}
TIME
RES
RT
OUT_B
REF
COMP
DCL
SYNC
SS
PGND AGND
SYNC I/O
ERROR
AMP and
ISOLATION
Figure 1. Simplified Forward Power Converter with Active Clamp Reset
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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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