SGS Thomson Microelectronics L4957V2.5, L4957V1.5, L4957D2.5, L4957D1.5 Datasheet



L4957

UP TO 4A ULDO LINEAR REGULATOR

1.5V AND 2.5VFIXEDOUTPUT VOLTAGE
3V TO 6.5V INPUTVOLTAGERANGE
200mΩ RdsonTYPICAL @ T

j = 125°C

0.6V max. DROP-OUTAT 2A
EXCELLENTLOAD REGULATION

0.6mAQUIESCENTCURRENTAT ANYLOAD
SHORT CIRCUIT PROTECTIONWITH FOLD-

BACK
THERMALSHUTDOWN

APPLICATIONS

MOTHERBOARDS
PROCESSORI/O & SUPPLIES
LOW VOLTAGE MEMORY & CHIP SET SUP-

PLIES
GRAPHIC& SOUND CARDS
LOW VOLTAGELOGIC SUPPLIES
POSTREGULATOR FOR SMPS

DESCRIPTION

The L4957 devicesare Ultra LowDrop Output lin­ear regulators with an internal N-channel MOS of
200mΩ particulary suitable for low voltage/low
dropout applications.

Operating with a input voltage from 3V to 6.5V
they are capable to deliver up to 4A at 1.5V or

2.5V fixed output voltages.

MULTIPOWER BCD TECHNOLOGY

3

1

D2PAKVersawatt TO-220

ORDERING NUMBERS:

L4957V1.5 L4957D1.5
L4957V2.5 L4957D2.5

The devices are ideal for use as one of the sup­plies required by processor, for example they are
the cost effectiveand efficientsolution for conver­sion from 3.3V (rail bus) to 2.5V @ 2.5A or to

1.5V with high current rating.
Fast response transient minimise the output ca-

pacitor value. A minimum of 22µF assures the
stabilityin allload conditions.

The on-chip trimming technique offers a tighter
voltage reference tolerance (with ±

2% including
line and load variation) beside to ensure a con­trolled short circuit current. Thermal shutdown
provides protection against overload conditions
that createsexcessivejunction temperature.

TYPICALAPPLICATION

3V to 6.5V

February 2000

C1

V

=1.5V/2.5V

OUTIN

1

3

OUT

L4957

2

GND

D97IN657E

C2

1/7

L4957

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

IN

T

i

T

stg

PINS CONNECTION

Supply Input Voltage 7 V
Junction Temperature -40 to +150 °C
Storage Temperature -40 to +150 °C

Versawatt (TO220)

BLOCK DIAGRAM

V

IN

10µF

IN

1

3

2

1

D98IN838B

OUT

GND

IN

3

2

GND

1

OUT

IN

D98IN933A

D2PAK

CURRENT

V

REF

LIMIT
WITH

FOLDBACK

CHARGE

PUMP

2/7

PRE

REGULATOR

+

E/A

-

BUFFER

THERMAL

SHUTDOWN

GND

2

POWER

DMOS

150mΩ

R

X

R

Y

3

OUT

D98IN839C

V

22µF

OUT

PIN FUNCTIONS

Pin N° Name Function

1 IN Unregulated input voltage; this pin mustbe bypassed with a capacitor larger than 10µF.
2 GND To connect to Ground to get 1.5V or2.5V output.
3 OUT Regulated output voltage. A minimum bypass capacitor of 22µF is required to insurestability.

THERMAL DATA

Symbol Parameter TO220 D2PAK Unit

R

th j-case

R

th j-amb

Thermal ResistanceJunction-case Max. 2.5 3 °C/W
Thermal ResistanceJunction-ambient Max. 50 60 °C/W
Thermal Shutdown Typ. 150 °C
Thermal Hysteresis Typ. 20 °C

L4957 - ELECTRICALCHARACTERISTICS (Tj=25°C, VIN=5V, unlessotherwise specified).

• =Specificationsreferred to T

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

IN

V

O

V

∆

DSON Drain-Source ON

R

I

O

I

Q

(1) GND connected to ground.

OperatingSupply Voltage
(1)

Output Voltage (1) ForL4957V1.5/D1.5

Load regulation (1) 0.1A < IO < 4A 2 10 mV

O

Resistance
Current Limiting 90% V
Short Circuit Current V
Quiescent Current 0.1A < IO<4A 3V<V
Ripple Rejection f = 120Hz,I

from0°Cto +125°C.

J

0.1A< I
3V < V

<4A; 3V< VIN<6.5V

O

<6.5V; 0.1A< I

IN

ForL4957V2.5/D2.5

0.1A< I
3V < V

O

V

IN

<4A; 3V< VIN<6.5V

O

<6.5V; 0.1A< IO<4A

IN

O

=0V • 1.8 A

O

=5V∆VIN=2V

=4A

3 6.5 V

<4A •

O

•

1.47

1.455

2.45

2.425

1.5

1.5

2.5

2.5

1.53

1.545

2.55

2.575

• 200 300 m

5.1 6.3 7.5 A

•

< 6.5V • 0.5 2 mA

IN

60 75 dB

PP

L4957

V
V

V
V

Ω

Figure 1: Line Regulation vs. Junction

Temperature

5

4.5
4

3.5
3

2.5
2

Output Voltage Deviation [mV]

1.5
1

0.5
0

-40 -20 0 20 40 60 80 100 120 140 160

3V < Vin < 6.5V
Iout = 10mA

Tj [°C]

Figure2: LoadRegulation

5
4
3
2
1
0

Output VoltageDeviation [mV]

-1

-2

-3

-4

-5
012345

(Pulsed technique has been used)

Vin = 5V
Tj = 25 °C

Vout = 1.5V

Iout [A]

3/7