L5970D
Up to 1A step down switching regulator
Features
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Up to 1A output current
Operating input voltage from 4.4V to 36V
3.3V / (±2%) reference voltage
Output voltage adjustable from 1.2V to 35V
Low dropout operation: 100% duty cycle
250KHz Internally fixed frequency
Voltage feedforward
Zero load current operation
Internal current limiting
Inhibit for zero current consumption
Synchronization
Protection against feedback disconnection
Thermal shutdown
SO8
Description
The L5970D is a step down monolithic power
switching regulator capable to deliver up to 1A at
output voltages from 1.2V to 35V.
The device uses an internal P-Channel D-MOS
transistor (with a typical Rdson of 250mΩ) as
switching element to minimize the size of the
external components.
An internal oscillator fixes the switching frequency
at 250KHz.
Having a minimum input voltage of 4.4V only, it is
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.
Applications
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Consumer: STB, DVD, TV, VCR, car radio,
LCD monitors
Networking: XDSL, modems, DC-DC modules
Computer: printers, audio/graphic cards,
optical storage, hard disk drive
Industrial: changers, car battery, DC-DC
converters
Test application circuit
3.3V
VIN = 4.4V to 35V
VREF
VCC
SYNC.
C1
10µF
35V
CERAMIC
COMP
C4
22nF
C3
220pF
6
8
2
4
INH.
R3
4.7K
Figure 1.
1
OUT
L1 33µH
D1
STPS2L40U
VOUT=3.3V
L5970D
3
7
5
GND
FB
R1
5.6K
C2
100µF
10V
R2
3.3K
D98IN954C
October 2007
Rev 16
1/16
16
STMICROELECTRONICS [ STMICROELECTRONICS ]
