ADP1821ARQZ-R7 datasheet(22/24 Pages) AD

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ADP1821

Rev. B | Page 22 of 24

The ADP1821 can also be configured to run with an input voltage

higher than 5.5 V. Figure 22 shows a typical application circuit

that operates from a 12 V input. An external LDO is built, with

a NPN, a 5.6 V Zener diode and a resistor, to step down the

input voltage from 12 V to 5 V to power the ADP1821. These

external signal components are cheap and small in size. Alter-

natively, LDOs such as the ADP3300 or the ADP3330 in a small

SOT-23 package can be used for input voltages up to 12 V.

GND

PVCC

ADP1821

SHDN

VCC

BST

CSL

PGND

FREQ

SYNC

PWGD

COMP

1µF

10Ω

20kΩ

2.7kΩ

10kΩ

100kΩ

L1 = 2.2µH

OUTPUT

1.8V, 10A

INPUT

12V

AGND

CSS

100nF

82kΩ

1nF

18pF

0.22µF

CIN1

10µF

16V

CIN2

180µF

20V

COUT1

10µF

6.3V

×2

COUT2

680µF

×2

1.8nF

fSW = 300kHz

CIN2: SANYO, OSCON 20SP180M

COUT2: SANYO, OSCON 4SEPC680M

D2: CENTRAL SEMI, CMOZ5V6, 5.6V ZENER

L1: COILTRONICS, HC7-2R2

Q1: CENTRAL SEMI, CMST2222A, NPN

D1: CENTRAL SEMI, CMDSH2-4L

M1, M2: IRFR3709Z

R4 3.3kΩ

1.2kΩ

Figure 22. Typical Application Circuit, 12 V Input

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