L5970AD Datasheet, PDF (1/11 Pages) STMicroelectronics – 1.5A SWITCH STEP DOWN SWITCHING REGULATOR

L5970AD
1.5A SWITCH STEP DOWN SWITCHING REGULATOR
1 General Features
■ 1.5A 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
■ 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
Figure 1. Package
SO-8
Table 1. Order Codes
Part Number
L5970AD
L5970ADTR
Package
SO-8
SO-8 in Tape & Reel
2 Description
The L5970AD is a step down monolithic power
switching regulator with a switch current limit of 1.5A
so it is able to deliver more than 1A DC current to the
load depending on the application conditions.
The output voltage can be set from 1.235V to 35V.
The device uses an internal P-Channel D-MOS tran-
sistor (with a typical R_DSON 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 _L5970AD
SYNC. 2
C1
10µF
35V
CERAMIC
COMP
C4
22nF
4
3
INH
C3
220pF
R3
4.7K
5
7
GND
OUT ^{L1 15µH}
VOUT=3.3V
D1
STPS2L25U ^R1
5.6K
FB
R2
3.3K
C2
330µF
10V
March 2005
D05IN1530
Rev. 1
1/11