LM5009A Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – 100V, 150 mA Constant On-Time Buck Switching Regulator

LM5009A
June 26, 2009
100V, 150 mA Constant On-Time Buck Switching Regulator
General Description
The LM5009A is a functional variant of the LM5009 COT Buck
Switching Regulator. The functional differences of the
LM5009A are: The minimum input operating voltage is 6 volts,
the on-time equation is slightly different, and the requirement
for a minimum load current is removed.
The LM5009A 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 control scheme using
an ON time inversely proportional to V_IN. This feature allows
the operating frequency to remain relatively constant. The
control scheme 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 control while providing minimum foldback. Other fea-
tures include: Thermal Shutdown, V_CC under-voltage lockout,
Gate drive under-voltage lockout, Max Duty Cycle limiter, and
a pre-charge switch.
Features
■ ^{Operating input voltage range: 6V to 95V}
■ ^{Integrated 100V, N-Channel buck switch}
■ ^{Internal start-up regulator}
■ ^{No loop compensation required}
■ ^{Ultra-Fast transient response}
■ ^{On time varies inversely with input voltage}
■ ^{Operating frequency remains constant with varying line}
voltage and load current
■ ^{Adjustable output voltage from 2.5V}
■ ^{Highly efficient operation}
■ ^{Precision internal reference}
■ ^{Low bias current}
■ ^{Intelligent current limit}
■ ^{Thermal shutdown}
Typical Applications
■ ^{Non-Isolated Telecommunication Buck Regulator}
■ ^{Secondary High Voltage Post Regulator}
■ ^{+42V Automotive Systems}
Package
■ ^{MSOP - 8}
■ ^{LLP - 8 (4mm x 4mm)}
Typical Application, Basic Step-Down Regulator
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