L4976_07 Datasheet, PDF (1/17 Pages) STMicroelectronics – 1A step down switching regulator

L4976
1A step down switching regulator
Features
■ Up to 1A step down converter
■ Operating input voltage from 8v to 55v
■ Precise 5.1V reference voltage
■ Output voltage adjustable from 0.5V to 50V
■ Switching frequency adjustable up to 300kHz
■ Voltage feedforward
■ Zero load current operation
■ Internal current limiting (pulse-bypulse
■ and hiccup mode)
■ Protection against feedback disconnection
■ Thermal shutdown
Figure 1. Typical application circuit
DIP8
SO16W
Description
The L4976 is a step down monolithic power
switching regulator delivering 1A at a voltage
between 3.3V and 50V (selected by a simple
external divider). Realized in BCD mixed
technology, the device uses an internal power D-
MOS transistor (with a typical R_ds(ON) of 0.25Ω) to
obtain very high efficency and high switching
speed. A switching frequency up to 300KHz is
achievable (the maximum power dissipation of the
packages must be observed). A wide input
voltage range between 8V to 55V and output
voltages regulated from 3.3V to 40V cover the
majority of today’s applications. Features of this
new generations of DC-DC converter include
pulse-by-pulse current limit, hiccup mode for short
circuit protection, voltage feedforward regulation,
protection against feedback loop disconnection
and thermal shutdown. The device is available in
plastic dual in line, MINIDIP 8 for standard
assembly, and SO16W for SMD assembly.
Vi=8V to 55V
5
8
R₁
20K
L4976
3
4
C₁
C₇
220µF 220nF
C₂
2.7nF
2
7
16
63V
L1
260µH
(77120)
V_O=3.3V/1A
R₂
9.1K
C₄
22nF
C₆
100nF
D1
GI
SB360
C₈
330µF
April 2007
Rev 7
1/17
www.st.com
17