L4971 查看數據表（PDF） - STMicroelectronics
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L4971 Datasheet PDF : 13 Pages
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L4971
1.5A STEP DOWN SWITCHING REGULATOR
1 FEATURES
■ UP TO 1.5A STEP DOWN CONVERTER
■ OPERATING INPUT VOLTAGE FROM 8V TO
55V
■ PRECISE 3.3V (±1%) INTERNAL
REFERENCE VOLTAGE
■ OUTPUT VOLTAGE ADJUSTABLE FROM
3.3V TO 50V
■ SWITCHING FREQUENCY ADJUSTABLE UP
TO 300KHz
■ VOLTAGE FEEDFORWARD
■ ZERO LOAD CURRENT OPERATION
■ INTERNAL CURRENT LIMITING (PULSE-
BYPULSE AND HICCUP MODE)
■ INHIBIT FOR ZERO CURRENT
CONSUMPTION
■ PROTECTION AGAINST FEEDBACK
DISCONNECTION
■ THERMAL SHUTDOWN
■ 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 0.25Ω) 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 today’s 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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