LM5041A Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – Cascaded PWM Controller

May 2005
LM5041A
Cascaded PWM Controller
General Description
The LM5041A PWM controller contains all of the features
necessary to implement either current-fed or voltage-fed
push-pull or bridge power converters. These “Cascaded”
topologies are well suited for multiple output and higher
power applications. The LM5041A’s four control outputs in-
clude: the buck stage controls (HD and LD) and the push-
pull control outputs (PUSH and PULL). Push-pull outputs are
driven at 50% nominal duty cycle at one half of the switching
frequency of the buck stage and can be configured for either
a guaranteed overlap time (for current-fed applications) or a
guaranteed both-off time (for voltage-fed applications).
Push-pull stage MOSFETs can be driven directly from the
internal gate drivers while the buck stage requires an exter-
nal driver such as the LM5102. The LM5041A includes a
high-voltage start-up regulator that operates over a wide
input range of 15V to 100V. The PWM controller is designed
for high-speed capability including an oscillator frequency
range up to 1 MHz and total propagation delays of less than
100ns. Additional features include: line Under-Voltage Lock-
out (UVLO), soft-start, an error amplifier, precision voltage
reference, and thermal shutdown.
The two differences between the LM5041 and the LM5041A
are: No second level current limit in the ’A’ version No
softstart (SS) shutdown comparator in the ’A’ version .
Features
n Internal Start-up Bias Regulator
n Programmable Line Under-Voltage Lockout (UVLO) with
Adjustable Hysteresis
n Current Mode Control
n Internal Error Amplifier with Reference
n Cycle-by-cycle Over-Current Protection
n Leading Edge Blanking
n Programmable Push-Pull Overlap or Dead Time
n Internal 1.5A Push-Pull Gate Drivers
n Programmable Soft-start
n Programmable Oscillator with Sync Capability
n Precision Reference
n Thermal Shutdown
Applications
n Telecommunication Power Converters
n Industrial Power Converters
n Multi-Output Power Converters
n +42V Automotive Systems
Packages
n TSSOP-16
n LLP-16 (5x5 mm) Thermally Enhanced
Typical Application Circuit
Simplified Cascaded Push-Pull Power Converter
© 2005 National Semiconductor Corporation DS201378
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