L5973AD Datasheet, PDF (1/14 Pages) STMicroelectronics – 2A SWITCH STEP DOWN SWITCHING REGULATOR

L5973AD
2A SWITCH STEP DOWN SWITCHING REGULATOR
1 GENERAL FEATURES
■ 2A 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
■ 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
1.1 APPLICATIONS:
■ 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
2 DESCRIPTION
The L5973AD is a step down monolithic power
Figure 1. Package
HSOP8 (Exposed pad)
Table 1. Order Codes
Part Number
L5973AD
L5973ADTR
Package
HSOP8
HSOP8 in Tape & Reel
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 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 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 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.
Figure 2. Test and Application Circuit
VREF
3.3V
6
1
VIN = 4.4V to 35V
VCC
8 _L5973AD
SYNC. 2
C1
10µF
35V
CERAMIC
COMP
C4
22nF
4
3
INH
C3
220pF
R3
4.7K
5
7
GND
OUT
FB
L1 15µH
D1
STPS340U
VOUT=3.3V
R1
5.6K
R2
3.3K
C2
330µF
10V
December 2004
D03IN1453
Rev. 3
1/14