L5973AD
2A switch step down switching regulator
General features
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2A Internal switch
Operating input voltage from 4V to 36V
3.3V / (±2%) reference voltage
Output voltage adjustable from 1.235V to 35V
Low dropout operation: 100% duty cycle
500KHz 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
Description
The L5973AD is a step down monolithic power
switching regulator with a switch current limit of
2A so it is able to deliver more than 1.5A 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 reduce the R
thJA
down to approximately
40°C/W.
The device uses an internal P-Channel D-MOS
transistor (with a typical of 200mΩ) as switching
element to avoid the use of bootstrap capacitor
and guarantee high efficiency.
An internal oscillator fixes the switching frequency
at 500KHz to minimize the size of external
components.
Having a minimum input voltage of 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.
OUT
L1 15µH
D1
STPS340U
5
FB
GND
R2
3.3K
VOUT=3.3V
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: chargers, car battery, DC-DC
converters
Test application circuit
3.3V
VIN = 4V to 35V
VREF
VCC
SYNC.
C1
10µF
35V
CERAMIC
COMP
C4
22nF
C3
220pF
R3
4.7K
6
8
2
4
INH
1
L5973AD
3
7
R1
5.6K
C2
330µF
10V
D03IN1453
January 2007
Rev 6
1/21
21
STMICROELECTRONICS [ STMICROELECTRONICS ]
