uses an internal power D-MOS transistor (with a

typical Rdson of 0.15ohm) to obtain very high effi-

ciency and very fast switching times.

Switching frequency up to 300KHz are achievable

(the maximum power dissipation of the packages

must be observed).

A wide input voltage range between 8V to 55V

and output voltages regulated from 3.3V to 40V

cover the majority of the today applications.

Features of this new generation of DC-DC con-

verter includes pulse by pulse current limit, hiccup

mode for output short circuit protection, voltage

feed forward regulation, soft start, input/output

synchronization, protection against feedback loop

disconnection, inhibit for zero current consump-

tion and thermal shutdown.

Packages available are in plastic dual in line, DIP-

18 (12+3+3) for standard assembly, and SO20

(12+4+4) for SMD assembly.

PIN CONNECTIONS (Top view)

OSC

OUT

OUT

GND

GND

GND

V

CC

BOOT

1

3

2

4

5

6

7

8

9

INH

VFB

COMP

GND

GND

GND

V5.1

SS

SYNC

18

17

16

15

14

12

13

11

10

D94IN162A

POWERDIP (12+3+3)

OSC

OUT

OUT

GND

GND

GND

GND

VFB

COMP

GND

GND

GND

GND

V5.1

SS

SYNC

1

3

2

4

5

6

7

8

9

18

17

16

15

14

12

13

11

19

10

20

BOOT

INH

D94IN163A

SO20 (12+4+4)

VREF

GOOD

5.1V

COMP

VFB

SYNC

BOOT

DRIVER

HICCUP CURRENT

LIMITING

INTERNAL

REFERENCE

SS

INH

ZERO CURRENT

INHIBIT

D94IN161B

+

-

3.3V

V5.1

E/A

SOFT

START

5.1V

3.3V

THERMAL

SHUTDOWN

INTERNAL

SUPPLY

5.1V

-

+

PWM

CURRENT

LIMITING

R

S

Q

Q

CBOOT

CHARGE

OSCILLATOR

OUT

OUT

GND

OSC

V

CC

V

CC

17(19)

11(12)

12(13)

18(20)

1(1)

2(2)

3(3)

9(10)

8(9)

7(8)

16(18)

10(11)

4,5,6,13,14,15

(4,5,6,7,14,15,16,17)

Pin x = Powerdip

Pin (x) = S020

BLOCK DIAGRAM

L4973V3.3 - L4973V5.1 - L4973D3.3 - L4973D5.1

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