LM34919_14 Datasheet, PDF (7/21 Pages) Texas Instruments – Ultra-Small 40-V 600-mA Constant On-Time Buck Switching Regulator

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VIN
VCC
UVLO
LM34919
SNOSAY2D – MAY 2007 – REVISED JUNE 2008
7.0V
SW Pin
Inductor
Current
SS Pin
2.5V
V_OUT
t1
t2
Figure 3. Start Up Sequence
FUNCTIONAL DESCRIPTION
The LM34919 Step Down Switching Regulator features all the functions needed to implement a low cost, efficient
buck bias power converter capable of supplying at least 0.6A to the load. This high voltage regulator contains an
N-Channel buck switch, is easy to implement, and is available in micro SMD package. The regulator's operation
is based on a constant on-time control scheme, where the on-time is determined by V_IN. This feature allows the
operating frequency to remain relatively constant with load and input voltage variations. The feedback control
requires no loop compensation resulting in very fast load transient response. The valley current limit detection
circuit, internally set at 0.64A, holds the buck switch off until the high current level subsides. This scheme
protects against excessively high current if the output is short-circuited when V_IN is high.
The LM34919 can be applied in numerous applications to efficiently regulate down higher voltages. Additional
features include: Thermal shutdown, V_CC under-voltage lockout, gate drive under-voltage lockout, and maximum
duty cycle limiter.
Copyright © 2007–2008, Texas Instruments Incorporated
Product Folder Links: LM34919
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