SGS Thomson Microelectronics L5972D Datasheet
2A SWITCH STEP DOWN SWITCHING REGULATOR
■ 2A INTERNAL SWITCH
■ OPERATING INPUT VOLTAGE FROM 4.4V
TO 36V
■ OUTPUT VOLTAGE ADJUSTABLE FROM
1.235V TO 35V
■ LOW DROPOUT OPERATION: 100% DUTY
CYCLE
■ 250KHz INTERNALLY FIXED FREQUENCY
■ VOLTAGE FEEDFO RWA R D
■ ZERO LOAD CURRENT OPERATION
■ INTERNAL CURRENT LIMITING
■ PROTECTION AGAINST FEEDBACK
DISCONNECTION
■ THERMAL SHUTDOWN
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
L5972D
SO8 (4+2+2)
ORDERING NUMBERS: L5972D (SO8)
L5972D013TR (Tape & Reel)
DESCRIPTION
The L5972D is a step down monolithic power switching regulator with a minimum 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 device uses an internal P-Channel D-MOS tran-
sistor (with a typical Rdson of 250m
element to minimize the s i ze of t he ext ernal c omponents.
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, availabl e in all computer related applications.
Pulse by pulse current limit with the internal frequency modulation offers an effective constant current
short circuit protection.
Ω
) as swi tch ing
TEST APPLICATION CIRCUIT
VIN = 4.4V to 35V
C1
10µF
35V
CERAMIC
May 2003
C4
22nF
C3
220pF
VCC OUT
COMP
R3
4.7K
8
4
6
L5972D
2
3
1
5
7
GND
D03IN1436
FB
L1 33µH
D1
STPS2L40U
R1
5.6K
R2
3.3K
VOUT=3.3V
C2
100µF
10V
1/10
L5972D
PIN CONNECTION
OUT
GND
GND
COMP
1
2
3
4
8
7
6
5
D02IN1367
VCC
GND
GND
FB
PIN DESCRIPT ION
N° Pin Function
1 OUT Regulator Output.
2,3,6,7 GND Ground.
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.
8 VCC Unregulated DC input voltage.
THERMAL DATA
Symbol Parameter Value Unit
R
th (j-amb)
(*) Package mounted on board (4cm2 ground-plane)
Thermal Resistance Junction to ambient Max. 65 (*) °C/W
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
Input Voltage 40 V
8
Out pin DC voltage
1
Out pin peak voltage at ∆t = 0.1µs
Maximum output current int. limit.
Analog pins 4 V
5
Power dissipation at Tamb ≤ 70°C 1.2 W
Operating junction temperature range -40 to 150 °C
j
Storage temperature range -55 to 150 °C
-1 to 40
-5 to 40
2/10
V
V
I
1
V4, V
P
tot
T
T
stg
V
V
L5972D
ELECTRICAL CHARACTERISTICS
(Tj = 25°C, VCC = 12V, unless otherwise specified.)
(*) Specification Referred to Tj from -40 to 125°C.
Symbol Parameter Test Condition Min. Typ. Max. Unit
V
DYNAMIC CHARACTERISTICS (see test circuit ).
DC CHARACTERISTICS
I
Operating input voltage range Vo = 1.235V; Io = 1.5A * 4.4 36 V
CC
V
Dropout voltage VCC = 4.4V; Io = 1.5A * 0.375 0.75 V
d
I
Maximum limiting current VCC = 4.4V to 36V * 2 2.5 3 A
l
Switching frequency * 212 250 280 KHz
f
s
225 250 275 KHz
Duty cycle 0 100 %
Voltage feedback 4.4V < VCC < 36V,
V
5
20mA < IO < 1.5A
h Efficiency V
Total operating quiescent current * 3 5 mA
qop
I
Quiescent current Duty Cycle = 0; VFB = 1.5V 2.5 mA
q
= 5V, VCC = 12V 90 %
O
1.220 1.235 1.25 V
* 1.198 1.235 1.272 V
ERROR AMPLIFIER
V
V
I
o source
I
o sink
High level output voltage VFB = 1V 3.5 V
OH
Low level output voltage VFB = 1.5V 0.4 V
OL
Source output current V
Sink output current V
I
Source bias current 2.5 4 µA
b
DC open loop gain RL = ∞ 50 65 dB
gm Transconductance I
= 1.9V; VFB = 1V 200 300 µA
COMP
= 1.9V; VFB = 1.5V 1 1.5 mA
COMP
= -0.1mA to 0.1mA
comp
V
= 1.9V
COMP
2.3 mS
3/10
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