LM5008
High Voltage (100V) Step Down Switching Regulator
General Description
The LM5008 Step Down Switching Regulator features all of
the functions needed to implement a low cost, efficient, Buck
bias regulator. This high voltage regulator contains an 100 V
N-Channel Buck Switch. The device is easy to implement
and is provided in the MSOP-8 and the thermally enhanced
LLP-8 packages. The regulator is based on a hysteretic
control scheme using an ON time inversely proportional to
V
IN
. This feature allows the operating frequency to remain
relatively constant. The hysteretic control requires no loop
compensation. An intelligent current limit is implemented
with forced OFF time, which is inversely proportional to Vout.
This scheme ensures short circuit protection while providing
minimum foldback. Other protection features include: Ther-
mal Shutdown, V
CC
under-voltage lockout, Gate drive under-
voltage lockout, and Max Duty Cycle limiter
Features
n Integrated 100V, N-Channel buck switch
n Internal V
CC
regulator
n No loop compensation required
n Ultra-Fast transient response
n On time varies inversely with line voltage
n Operating frequency remains constant with varying line
voltage and load current
n Adjustable output voltage
n Highly efficient operation
n Precision internal reference
n Low bias current
n Intelligent current limit protection
n Thermal shutdown
Typical Applications
n Non-Isolated Telecommunication Buck Regulator
n Secondary High Voltage Post Regulator
n +42V Automotive Systems
Package
n MSOP - 8
n LLP - 8 (4mm x 4mm)
Connection Diagram
20097902
8-Lead MSOP, LLP
Ordering Information
Order Number Package Type NSC Package Drawing Supplied As
LM5008MM MSOP-8 MUA08A 1000 Units on Tape and Reel
LM5008SD LLP-8 SDC08A 1000 Units on Tape and Reel
October 2004
LM5008 High Voltage (100V) Step Down Switching Regulator
© 2004 National Semiconductor Corporation DS200979 www.national.com
ES250PW
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