L5972D
2A switch step down switching regulator
Features
2A internal switch
Operating input voltage from 4.4V to 36V
Output voltage adjustable from 1.235V to 35V
SO8
Low dropout operation: 100% duty cycle
250kHz Internally fixed frequency
Description
Voltage feedforward
Zero load current operation
The L5972D is a step down monolithic power
switching regulator with a minimum switch current
Internal current limiting
limit of 2A so it is able to deliver more than 1.5A
Protection against feedback disconnection
DC current to the load depending on the
Thermal shutdown
application conditions.
The output voltage can be set from 1.235V to 35V.
Applications
The device uses an internal P-Channel D-MOS
Consumer: STB, DVD, TV, VCR, car radio,
transistor (with a typical Rdson of 250m) as
LCD monitors
switching element to minimize the size of the
external components.
Networking: XDSL, modems, DC-DC modules
Computer: printers, audio/graphic cards, An internal oscillator fixes the switching frequency
optical storage, hard disk drive at 250kHz.
Industrial: changers, car battery, DC-DC
Having a minimum input voltage of 4.4V only, it is
converters
particularly suitable for 5V bus, available in all
computer related applications.
Pulse by pulse current limit with the internal
frequency modulation offers an effective constant
current short circuit protection.
Figure 1. Test application circuit
L1 33H
VOUT=3.3V
VIN = 4.4V to 35V VCC OUT
1
8
D1
R1
L5972D
STPS2L40U
COMP
5.6K
C2
C1 4
5
100F
10F
6 2 3 7
C4 FB
10V
35V
22nF
CERAMIC GND
R2
C3
3.3K
R3
220pF
4.7K
D03IN1436
October 2007 Rev 10 1/15
www.st.com 15Contents L5972D
Contents
1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2/15