L5973D
2.5A SWITCH STEP DOWN SWITCHING REGULATOR
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2.5A INTERNAL SWITCH
OPERATING INPUT VOLTAGE FROM 4.4V TO 36V
3.3V / (±2%) REFERENCE VOLTAGE
OUTPUT VOLTAGE ADJUSTABLE FROM
1.235V 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
HSOP8 - EXPOSED PAD
ORDERING NUMBER: L5973D
DESCRIPTION
The L5973D is a step down monolithic power switch-
ing regulator with a minimum switch current limit of
2.5A so it is able to deliver more than 2A DC current
to the load depending on the application conditions.
The output voltage can be set from 1.235V to 35V.
The high current level is also achieved thanks to an
SO8 package with exposed frame, that allows to re-
duce the R
th(j-amb)
down to approximately 40°C/W
The device uses an internal P-Channel D-MOS tran-
sistor (with a typical Rdson of 250mΩ) as switching
element to minimize the size of the external compo-
nents.
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 com-
puter related applications.
Pulse by pulse current limit with the internal frequen-
cy modulation offers an effective constant current
short circuit protection.
APPLICATIONS:
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CONSUMER: STB, DVD, TV, VCR,CAR
RADIO, LCD MONITORS
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NETWORKING: XDSL, MODEMS,DC-DC
MODULES
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COMPUTER: PRINTERS, AUDIO/GRAPHIC
CARDS, OPTICAL STORAGE, HARD DISK
DRIVE
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INDUSTRIAL: CHARGERS, 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
R3
4.7K
6
8
2
4
INH
1
OUT
L1 15µH
D1
STPS340U
VOUT=3.3V
L5973D
3
7
5
FB
GND
R1
5.6K
C2
330µF
10V
R2
3.3K
D03IN1439
May 2003
1/10
STMICROELECTRONICS [ STMICROELECTRONICS ]
