Datasheet

ADP1821
Rev. C | Page 22 of 24
The ADP1821 can also be configured to run with an input voltage
higher than 5.5 V.
Figure 23 shows a typical application circuit
that operates from a 12 V input. An external LDO is built, with
an 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
DH
SW
CSL
DL
PGND
FB
FREQ
SYNC
PWGD
COMP
SS
C5
1µF
C6
1µF
R7
10Ω
R1
20kΩ
R3
2.7kΩ
R2
10kΩ
R6
100kΩ
M1
M2
L1 = 2.2µH
OUTPUT
1.8V, 10A
INPUT
12V
D1
AGND
C
SS
100nF
R8
82kΩ
C3
1nF
C2
18pF
C4
0.22µF
C
IN1
10µF
16V
+
C
IN2
180µF
20V
C
OUT1
10µF
6.3V
×2
+
C
OUT2
680µF
4V
×2
C1
1.8nF
f
SW
= 300kHz
C
IN2
: SANYO, OSCON 20SP180M
C
OUT2
: 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
V
E
D2
Q1
R5
1.2kΩ
0
5310-022
Figure 23. Typical Application Circuit, 12 V Input