LM34919B Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – Ultra Small 40V, 600 mA Constant On-Time Buck Switching Regulator

LM34919B
May 26, 2010
Ultra Small 40V, 600 mA Constant On-Time Buck Switching
Regulator
General Description
The LM34919B Step Down Switching Regulator features all
of the functions needed to implement a low cost, efficient,
buck bias regulator capable of supplying 0.6A to the load. This
buck regulator contains an N-Channel Buck Switch, and is
available in a micro SMD package. The constant on-time
feedback regulation scheme requires no loop compensation,
results in fast load transient response, and simplifies circuit
implementation. The operating frequency remains constant
with line and load variations due to the inverse relationship
between the input voltage and the on-time. The valley current
limit results in a smooth transition from constant voltage to
constant current mode when current limit is detected, reduc-
ing the frequency and output voltage, without the use of
foldback. Additional features include: VCC under-voltage
lockout, thermal shutdown, gate drive under-voltage lockout,
and maximum duty cycle limiter.
Features
■ ^{AEC-Q100 Grade 1 qualified (-40°c to 125°c)}
■ ^{Maximum switching frequency: 2.6 MHz}
(V_IN=14V,V_o=3.3V)
■ ^{Input Voltage Range: 6V to 40V}
■ ^{Integrated N-Channel buck switch}
■ ^{Integrated start-up regulator}
■ ^{No loop compensation required}
■ ^{Ultra-Fast transient response}
■ ^{Operating frequency remains constant with load current}
and input voltage
■ ^{Maximum Duty Cycle Limited During Start-Up}
■ ^{Adjustable output voltage}
■ ^{Valley Current Limit At 0.64A}
■ ^{Precision internal reference}
■ ^{Low bias current}
■ ^{Highly efficient operation}
■ ^{Thermal shutdown}
Typical Applications
■ ^{Automotive Safety and Infotainment}
■ ^{High Efficiency Point-Of-Load (POL) Regulator}
■ ^{Non-Isolated Telecommunication Buck Regulator}
■ ^{Secondary High Voltage Post Regulator}
Package
■ ^{micro SMD (2mm x 2mm)}
Basic Step Down Regulator
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