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L4971_05 Datasheet, PDF (1/13 Pages) STMicroelectronics – 1.5A STEP DOWN SWITCHING REGULATOR | |||
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L4971
1.5A STEP DOWN SWITCHING REGULATOR
1 FEATURES
â UP TO 1.5A STEP DOWN CONVERTER
â OPERATING INPUT VOLTAGE FROM 8V TO
55V
â PRECISE 3.3V (±1%) INTERNAL
REFERENCE VOLTAGE
â OUTPUT VOLTAGE ADJUSTABLE FROM
3.3V TO 50V
â SWITCHING FREQUENCY ADJUSTABLE UP
TO 300KHz
â VOLTAGE FEEDFORWARD
â ZERO LOAD CURRENT OPERATION
â INTERNAL CURRENT LIMITING (PULSE-
BYPULSE AND HICCUP MODE)
â INHIBIT FOR ZERO CURRENT
CONSUMPTION
â PROTECTION AGAINST FEEDBACK
DISCONNECTION
â THERMAL SHUTDOWN
â SOFT START FUNCTION
2 DESCRIPTION
The L4971 is a step down monolithic power
switching regulator delivering 1.5A at a voltage be-
tween 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 Rdson of 0.25â¦) to obtain very high
efficency and high switching speed.
Figure 1. Package
DIP8
Table 1. Order Codes
Part Number
L4971
L4971D
L4971D013TR
SO16W
Package
DIP8
SO16W
SO16 in Tape & Reel
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 50V cover
the majority of todayâs applications.
Features of this new generations of DC-DC con-
verter include pulse-by-pulse current limit, hiccup
mode for short circuit protection, voltage feedfor-
ward regulation, soft-start, protection against feed-
back loop disconnection, inhibit for zero current
consumption and thermal shutdown.
The device is available in plastic dual in line, DIP8
for standard assembly, and SO16W for SMD as-
sembly.
Figure 1. Block Diagram
Vi=8V to 55V
C1
220µF
63V
C7
220nF
R1
20K
C2
2.7nF
C5
100nF
5
8
L4971
3
4
2
7
16
L1
126µH
(77120)
VO=3.3V/1.5A
R2
9.1K
C4
22nF
C6
100nF
D1
STPS
3L60U
C8
330µF
May 2005
D97IN748A
Rev. 11
1/13
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