STMicroelectronics L5973D User Manual

2.5A SWITCH STEP DOWN SWITCHING REGULATOR
2.5A INTERNAL SWITCH
OPERATING INPUT VOLTAGE FROM 4.4V TO 36V
3.3V / (±2%) REFERENCE VOLTAGE
OUTPUT VOLTAGE ADJUSTABLE FROM
LOW DROPOUT OPERATION: 100% DUTY
CYCLE
250KHz INTERNALLY FIXED FREQUENCY
VOLTAGE FEEDFO RWA R D
ZERO LOAD CURRENT OPERATION
INTERNAL CURRENT LIMITING
INHIBIT FOR ZERO CURRENT
CONSUMPTION
SYNCHRONIZATION
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
L5973D
HSOP8 - EXPOSED PAD
ORDERING NUMBERS: L5973D (Tube)
L5973D013TR (T & R)
DESCRIPTION
The L5973D is a step down monolithic power switch­ing regulator with a minimum switch current limit of
2.5A so it is able to deliver more than 2A 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
th(j-amb)
The device uses an internal P-Channel D-MOS tran­sistor (with a typical Rdson of 250m element to minimize the size of the external 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 frequen­cy modulation offers an effective constant current short circuit protection.
down to approximately 40°C/W
) as sw itchi ng
TEST APPLICATION CIRCUIT
3.3V
VIN = 4.4V to 35V
C1
10µF
35V
CERAMIC
September 2003
22nF
220pF
C4
C3
VREF
VCC
SYNC. COMP
R3
4.7K
6
8 2
4
L5973D
3
7
GNDINH
D03IN1439
OUT
1
5
FB
L1 15µH
D1
STPS340U
R1
5.6K
R2
3.3K
VOUT=3.3V
C2
330µF
10V
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L5973D
PIN CONNECTION
OUT
SYNC
INH
COMP
1 2 3 4
8 7 6 5
D98IN955
VCC GND VREF FB
PIN DESCRIPTION
Pin Function
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.
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
6 VREF 3.3V V 7 GND Ground. 8 VCC Unregulated DC input voltage.
When it is open an internal pull-up disable the device.
resistive divider is required for higher output voltages.
. No cap is requested for stability.
REF
THERMAL DATA
Symbol Parameter Value Unit
R
th (j-amb)
(*) Package mounted on board
Thermal Resistance Junction to ambient Max. 40 (*) °C/W
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Value Unit
V V
I
1
, V
V
4
V V
P
tot
T
T
stg
Input Voltage 40 V
8
Output DC voltage
1
Output peak voltage at t = 0.1µs Maximum output current int. limit. Analog pins 4 V
5
INH -0.3V to V
3
SYNC -0.3 to 4 V
2
Power dissipation at T Operating junction temperature range -40 to 150 °C
j
Storage temperature range -55 to 150 °C
60°C 2.25 W
amb
-1 to 40
-5 to 40
CC
V V
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L5973D
ELECTRICAL CHARACTERISTICS
(*) Specification Referred to Tj from -40 to 125°C
(Tj = 25°C, VCC = 12V, unless otherwise specified.)
(1)
.
Symbol Parameter Test Condition Min. Typ. Max. Unit
R
V
DSON
Operating input voltage range Vo = 1.235V; Io = 2A * 4.4 36 V
CC
Mosfet on Resistance * 0.250 0.5
I
Maximum limiting current VCC = 4.4V to 36V 2.5 3 3.5 A
l
Switching frequency * 212 250 280 KHz
f
s
225 250 275 KHz
Duty cycle 0 100 %
DYNAMIC CHARACTERISTICS (see test circuit ).
V
Voltage feedback 4.4V < VCC < 36V,
5
20mA < IO < 2A
η Efficiency V
O
= 5V, VCC = 12V 90 %
1.220 1.235 1.25 V
* 1.198 1.235 1.272 V
DC CHARACTERISTICS
I
Total Operating Quiescent
qop
*35mA
Current Quiescent current Duty Cycle = 0; VFB = 1.5V 2.5 mA
I
q
I
qst-by
Total stand-by quiescent current V
> 2.2V * 50 100 µA
inh
V
CC
= 36V; V
> 2.2V * 80 150 µA
inh
INHIBIT
INH Threshold Voltage Device ON 0.8 V
Device OFF 2.2 V
ERROR AMPLIFIER
V
V
I
o source
I
o sink
gm Transconductance I
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 Source bias current 2.5 4 µA
I
b
DC open loop gain R
= 1.9V; VFB = 1V 200 300 µA
COMP
= 1.9V; VFB = 1.5V 1 1.5 mA
COMP
= 50 57 dB
L
= -0.1mA to 0.1mA
comp
V
= 1.9V
COMP
2.3 mS
SYNC FUNCTION
High Input Voltage V Low Input Voltage V Slave Sink Current
Master Output Amplitude I Output Pulse Width no load, V
= 4.4V to 36V 2.5 V
CC
= 4.4V to 36V 0.74 V
CC
= 0.74V
V
sync
V
= 2.33V
sync
= 3mA 2.75 3 V
source
(2)
= 1.65V 0.20 0.35 µs
sync
0.11
0.21
0.25
0.45mAmA
REF
REFERENCE SECTION
Reference Voltage 3.234 3.3 3.366 V
I
= 0 to 5mA
REF
* 3.2 3.3 3.399 V
VCC = 4.4V to 36V
Line Regulation I
REF
= 0mA
510mV
VCC = 4.4V to 36V
Load Regulation I
= 0 to 5mA 8 15 mV
REF
Short Circuit Current 10 18 30 mA
Notes: 1. Specification over the -40 to +125 Tj Temp erature rang e are assured by design, characteri zation and st atistical correlation.
2. Guaranteed by design.
V
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