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STMicroelectronics |
L5970D
UP TO 1A STEP DOWN SWITCHING REGULATOR
s UP TO 1A OUTPUT CURRENT
s OPERATING INPUT VOLTAGE FROM 4.4V
TO 36V
s 3.3V / (±2%) / REFERENCE VOLTAGE
s OUTPUT VOLTAGE ADJUSTABLE FROM
1.2V TO 35V
s LOW DROPOUT OPERATION: 100% DUTY
CYCLE
s 250KHz INTERNALLY FIXED FREQUENCY
s VOLTAGE FEEDFORWARD
s ZERO LOAD CURRENT OPERATION
s INTERNAL CURRENT LIMITING
s INHIBIT FOR ZERO CURRENT
CONSUMPTION
s SINCHRONIZATION
s PROTECTION AGAINST FEEDBACK
DISCONNECTION
s THERMAL SHUTDOWN
APPLICATIONS:
s CONSUMER: STB, DVD, TV, VCR,CAR
RADIO, LCD MONITORS
s NETWORKING: XDSL, MODEMS,DC-DC
MODULES
s COMPUTER: PRINTERS, AUDIO/GRAPHIC
CARDS, OPTICAL STORAGE, HARD DISK
DRIVE
s INDUSTRIAL: CHARGERS, CAR BATTERY
DC-DC CONVERTERS
TEST APPLICATION CIRCUIT
SO8
ORDERING NUMBERS: L5970D (SO8)
L5970D013TR (T&R)
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 ex-
ternal 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 fre-
quency modulation offers an effective constant
current short circuit protection.
VREF
3.3V
VIN = 4.4V to 35V
VCC
SYNC.
6
8
2
L5970D
1
C1
10µF
35V
CERAMIC
COMP
C4
22nF
43
INH.
C3
220pF
R3
4.7K
5
7
GND
OUT L1 33µH
VOUT=3.3V
D1
STPS2L40U R1
FB
5.6K
C2
100µF
10V
R2
3.3K
D98IN954C
May 2003
1/10
L5970D
PINS CONNECTION (Top View)
OUT
SYNC
INH
COMP
18
27
36
45
D98IN955
VCC
GND
VREF
FB
PINS FUNCTION
N. Name
Description
1 OUT Regulator Output.
2 SYNC Master/slave synchronization.
3 INH A logical signal (active high) disables the device. If INH not used the pin must be grounded.
When it is open an internal pull-up disable the device.
4 COMP E/A output for frequency compensation.
5 FB Feedback input. Connecting directly to this pin results in an output voltage of 1.23V. An external
resistive divider is required for higher output voltages.
6 VREF 3.3V VREF. No cap is requested for stability.
7 GND Ground.
8 VCC Unregulated DC input voltage.
THERMAL DATA
Symbol
Parameter
Rth (j-amb) Thermal Resistance Junction to ambient Max.
(*) Package mounted on board
ABSOLUTE MAXIMUM RATINGS
Symbol
V8
V1
I1
V4, V5
V3
V2
Ptot
Tj
Tstg
Parameter
Input Voltage
Output DC voltage
Output peak voltage at t = 0.1µs
Maximum output current
Analog pins
INH
SYNC
Power dissipation at Tamb ≤ 60°C
Operating junction temperature range
Storage temperature range
Value
120 (*)
Unit
°C/W
Value
40
-1 to 40
-5 to 40
int. limit.
4
-0.3V to VCC
-0.3 to 4
0.75
-40 to 150
-55 to 150
Unit
V
V
V
V
V
W
°C
°C
2/10
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