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STMicroelectronics Electronic Components Datasheet

L5973AD Datasheet

2A SWITCH STEP DOWN SWITCHING REGULATOR

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L5973AD pdf
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 Rth(j-amb) down to approximately 40°C/W
The device uses an internal P-Channel D-MOS tran-
sistor (with a typical of 200m) 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
43
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


STMicroelectronics Electronic Components Datasheet

L5973AD Datasheet

2A SWITCH STEP DOWN SWITCHING REGULATOR

No Preview Available !

L5973AD pdf
L5973AD
Table 2. Thermal Data
Symbol
Parameter
Rth (j-amb) Thermal Resistance Junction to ambient
(*) Package mounted on board
Figure 3. Pin Connection (top view)
Max.
Value
40 (*)
Unit
°C/W
OUT
SYNC
INH
COMP
18
27
36
45
D98IN955
VCC
GND
VREF
FB
Table 3. Pin Description
N. Name
Description
1 OUT Regulator Output.
2 SYNC Master/Slave Synchronization. When it is open, a signal synchronous with the turn-off of the inter-
nal power is present at the pin. When connected to an external signal at a frequency higher than
the internal one, then the device is synchronized by the external signal.
Connecting together the SYNC pin of two devices, the one with the higher frequency works as
master and the other one, works as slave.
3 INH A logical signal (active high) disables the device. With IHN higher than 2.2V the device is OFF and with
INH lower than 0.8V, the device is ON.
If INH is not used the pin must be grounded. When it is open, an internal pull-up disables the device.
4 COMP E/A output to be used for frequency compensation.
5 FB Stepdown feedback input. Connecting the output voltage directly to this pin results in an output
voltage of 1.235V. An external resistor divider is required for higher output voltages (the typical
value for the resistor connected between this pin and ground is 4.7K).
6 VREF Reference voltage of 3.3V. No filter capacitor is needed to stability.
7 GND Ground.
8 VCC Unregulated DC input voltage.
Table 4. 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
40
-1 to 40
-5 to 40
int. limit.
4
-0.3V to VCC
-0.3 to 4
2.25
-40 to 150
-55 to 150
Unit
V
V
V
V
V
W
°C
°C
2/14


Part Number L5973AD
Description 2A SWITCH STEP DOWN SWITCHING REGULATOR
Maker STMicroelectronics
Total Page 14 Pages
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