7

Step Down DC - DC Converter Power IC

R/C

（L.Active）

S/S

UVLO

INVL

Current

Limit2

Current

Limit1

PWM Comp

VTS

amp-

OSC

7

3∼6

1,2,22∼25

8

19

15

14

13

11

12

16

10

P.GND1

20

ampOUT

−

＋

Error Amp

21

P.GND2

26

GND

9,17

ON/OFF

Control

Bandgap

Reference

1.26V±1％

Thermal

Shutdown

−

＋

−

＋

−

＋

Latch

Q R S

S R Q

Latch

OSC

−

＋

＋

−

＋

＋

−

S R Q

Latch

−

＋

18

＋

＋

GND

GND

INPUT

4.5∼20V

MD3221R

OUTPUT

0.8∼14V

ON

13

15

16

9,17 26

11

12

10

1,2,22∼25

8

19

3∼6

18

14

20

GND

VTS

ampOUT

amp-

S/S

P.GND2

P.GND1

GND

OSC

Vref

R/C

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

Feature

MD3221R

U097−2

(See the marking specification for the indication on the device)

wiring for f=300kHz

Block Diagram

Standard Connection Diagram

Pin Assignment (LSSOP26)

Input Voltage range 4.5V to 20V

Maximum Output Current 3A

Built_in MOSFETs for main switch and synchronous rectification

Adjustable output from 0.8V to 14V with external resistors

High Efficiency typ. 96% (at:Vin=5V, Vout=3.3V, Iout=1A, f=100kHz)

100kHz / 300kHz selectable switching frequency

Over Current Protection

Under Voltage Lockout

Thermal Shut Down

Remote On / Off

Supply current at remote off 25

μA typ.

Output

adjustable

Small

footprint

Remote

On/Off

Synchronous

Rectification

5V Input