push-pull or bridge power converters. These 鈥淐ascaded鈥?/div>
topologies are well suited for multiple output and higher
power applications. The LM5041鈥檚 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 LM5041 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.
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
Dual Mode 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
n
n
n
Telecommunication Power Converters
Industrial Power Converters
Multi-Output Power Converters
+42V Automotive Systems
Packages
n
TSSOP-16
n
LLP-16 (5x5 mm) Thermally Enhanced
Typical Application Circuit
20074901
Simplified Cascaded Push-Pull Power Converter
漏 2003 National Semiconductor Corporation
DS200749
www.national.com