LM34922_15 Datasheet, PDF (1/19 Pages) Texas Instruments – 28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit

LM34922
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SNVS813A – JUNE 2012 – REVISED MARCH 2013
LM34922 28V, 2A Constant On-Time Switching Regulator with Adjustable Current Limit
Check for Samples: LM34922
FEATURES
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•2 Input Operating Voltage Range: 6V to 28V
• Absolute Maximum Input Rating: 30V
• Integrated 2A N-Channel Buck Switch
• Adjustable Current Limit Allows for Smaller
Inductor
• Adjustable Output Voltage from 2.51V
• Minimum Ripple Voltage at V_OUT
• Power Good Output
• Switching Frequency Adjustable to 1MHz
• COT Topology Features:
– Switching Frequency Remains Nearly
Constant with Load Current and Input
Voltage Variations
– Ultra-Fast Transient Response
– No Loop Compensation Required
– Stable Operation with Ceramic Output
Capacitors
– Allows for Smaller Output Capacitor and
Current Sense Resistor
• Adjustable Soft-Start Timing
• Thermal Shutdown
• Precision 2% Feedback Reference
DESCRIPTION
The LM34922 Constant On-time Step-Down
Switching Regulator features all the functions needed
to implement a low cost, efficient, buck bias regulator
capable of supplying up to 2A of load current. This
voltage regulator contains an N-Channel Buck switch,
a startup regulator, current limit detection, and
internal ripple control. The constant on-time
regulation principle requires no loop compensation,
results in fast load transient response, and simplifies
circuit implementation. The operating frequency
remains constant with line and load. The adjustable
valley current limit detection results in a smooth
transition from constant voltage to constant current
mode when current limit is reached, without the use
of current limit foldback. The PGD output indicates
the output voltage has increased to within 5% of the
expected regulation value. Additional features
include: Low output ripple, VIN under-voltage lock-
out, adjustable soft-start timing, thermal shutdown,
gate drive pre-charge, gate drive under-voltage lock-
out, and maximum duty cycle limit.
Typical Application, Basic Step-Down Regulator
6V to 28V
Input
CIN
VIN
BST
LM34922
RT
SW
CBST
L1
VPGD
Power
Good
RPGD
CSS
RT
PGD
SS
SGND
D1
CS
RS
CSG
FB
RFB2
RFB1
VOUT
COUT
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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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