lm25085asdx National Semiconductor Corporation, lm25085asdx Datasheet
lm25085asdx
Manufacturer Part Number
lm25085asdx
Description
42v Constant On-time Pfet Buck Switching Controller With 0.9v Reference
Manufacturer
National Semiconductor Corporation
Datasheet
1.LM25085ASDX.pdf
(24 pages)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
lm25085asdx/NOPB
Manufacturer:
NS
Quantity:
540
© 2009 National Semiconductor Corporation
42V Constant On-Time PFET Buck Switching Controller
with 0.9V Reference
General Description
The LM25085A is a functional variant of the LM25085 COT
PFET Buck Switching Controller. The functional differences
of the LM25085A are: The feedback reference voltage is
0.9V, the forced off-time after current limit detection is longer,
and the soft-start time is shorter (1.8 ms).
The LM25085A is a high efficiency PFET switching regulator
controller that can be used to quickly and easily develop a
small, efficient buck regulator for a wide range of applications.
This high voltage controller contains a PFET gate driver and
a high voltage bias regulator which operates over a wide 4.5V
to 42V input range. The constant on-time regulation principle
requires no loop compensation, simplifies circuit implemen-
tation, and results in ultra-fast load transient response. The
operating frequency remains nearly constant with line and
load variations due to the inverse relationship between the
input voltage and the on-time. The PFET architecture allows
100% duty cycle operation for a low dropout voltage. Either
the R
used to sense current for over-current detection.
Typical Application, Basic Step Down Controller
DS(ON)
of the PFET or an external sense resistor can be
300852
LM25085A
Features
■
■
■
■
■
■
■
■
■
■
■
■
Package
■
■
■
Wide 4.5V to 42V input voltage range
Adjustable current limit using R
resistor
Programmable switching frequency to 1MHz
No loop compensation required
Ultra-Fast transient response
Nearly constant operating frequency with line and load
variations
Adjustable output voltage from 0.9V
Precision ±2% feedback reference
Capable of 100% duty cycle operation
Internal soft-start timer
Integrated high voltage bias regulator
Thermal shutdown
MSOP-8EP
MSOP-8
LLP-8 (3 mm x 3 mm)
DS(ON)
or a current sense
March 16, 2009
www.national.com
30085201