LM34923
www.ti.com
SNVS695A –MARCH 2011–REVISED FEBRUARY 2013
80-V 600-mA Constant On-Time Buck Switching Regulator
Check for Samples: LM34923
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FEATURES
DESCRIPTION
The LM34923 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 80V N-Channel
MOSFET Switch and a startup regulator. The device
is easy to implement and is provided in an 10-pin
VSSOP package. The regulator’s control scheme
uses an on-time inversely proportional to VIN. This
feature results in the operating frequency remaining
relatively constant with line and load variations. The
control scheme requires no loop compensation,
resulting in fast transient response. An intelligent
current limit is implemented with a forced off-time
which is inversely proportional to VOUT. This scheme
ensures short circuit control while providing minimum
foldback. Other features include: Thermal Shutdown,
VCC Under Voltage Lock-out, Max Duty Cycle
Limiter, a Pre-charge Switch, and a programmable
Under Voltage Detector with a status flag output.
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Operating Input Voltage Range: 6V to 75V
Integrated 80V, N-Channel Buck Switch
Internal Start-up Regulator
No Loop Compensation Required
Ultra-Fast Transient Response
Operating Frequency Remains Constant with
Line and Load Variations
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Adjustable Output voltage From 2.5V
Precision Internal Reference, ±2.5%
Intelligent Current Limit Reduces Foldback
Programmable Input UV Detector with Status
Flag Output
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Pre-charge Switch Enables Bootstrap Gate
Drive with No Load
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Thermal Shutdown
10-Pin VSSOP Package
APPLICATIONS
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Non-Isolated Telecommunication Buck
Regulator
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Secondary High Voltage Post Regulator
+42V Automotive Systems
Typical Application, Basic Step-Down Regulator
6V - 75V
Input
V
VIN
VCC
C3
IN
LM34923
C1
R
T
GND
BST
C4
L1
RT/SD
UV
SW
SHUTDOWN
V
OUT
R
UV2
D1
R3
C2
R
FB2
R
UV1
FB
R
UVO
GND
R
FB1
UVO
RTN
UV STATUS
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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