AIC1550 AIC [Analog Intergrations Corporation], AIC1550 Datasheet - Page 13

• Manufacturer Part Number: AIC1550
• Description: Low-Noise Synchronous PWM Step-Down DC/DC Converter
• Manufacturer: AIC [Analog Intergrations Corporation]

According the datas above, the Schottky diode,
SS12, from GS is recommend.
For feedback resistors, choose R2=390kΩ and R1
can be calculated as follow:
Fig. 22 shows the application circuit of AIC1550,
and Fig. 23 to 26 show the layout diagrams of it.
2. Ceramic capacitors application:
Of the same AIC1550 application above, except
for ceramic capacitor used, Co, R1, and R2 can
be calculated as following formulas. And the same
values of load current and output voltage at
800mA and 1.8V respectively are used.
I
I
R
, D
, D
1
MAX
avg
=
(



ON
(
1
ON
. 0
8 .
)
75
)
V
=
=
=
V
C
C
L: TDK SLF6025-100M1R0
D1: GS SS12
=
=
=
1 (
1 (
457
−
IN
IN
O1
I
925
800
: NIPPON 10µF/6V Tantalum capacitor
1
= 2.5V to 6.5V
−
−
: NIPPON 33µF/6V Tantalum capacitor
OUT



+
D
1
4
.
×
Fig. 23 AIC1550 Application Circuit (Tantalum capacitor application)
14
8 .
mA
)
2 .
mA
,
390
MAX
×
BP
C
10µF
mA
)
I
IN
OUT
×
k
+
800
+
Ω
250
∆
C
0.1µF
=
2
BP
I
mA
L
2
546
mA
k
Ω
1
2
3
4
; use 560kΩ
SHDN
FB
VIN
BP
AIC1550
SYNC/
MODE
GND
RT
LX
8
6
5
7
** Note: Efficiency can boost 2% to 4% if D1 is connected.
* Note: C
V
Let L1 = 6.8µH, and choose CF = 12pF, R1 =
820kΩ.
Co calculated by the following formula can
improve circuit stability.
Therefore,
Say, C
equation (8) as
So, R2 = 560kΩ.
Note: Schottky diode, SS12 from GS, is still
required in this application.
O1
L1
C
R2
R1
OUT
**
can be omitted if C
SS12
Optional
L1
O
>
D1
=
×
=
1
is substituted by 1.8V in equation (2) as
10µF
V
0.54
C
V
L1
OUT
(
O
V
R1
OUT
O
ref
is 22µF. Then, R2 can be decided by
×
≅
L1
CF
R1
560K
=
R2
390K
R1
−
0.54
O2
1
1.8
)
2
×
1
in 10µF Ceramic
=
CF
CF
10P
=
0.75
1.8
=
(
820k
3.33
+
*C
33µF
−
O1
V
6.8µ.
1
OUT
µ
×
=
H
12pF
1.4
= 1.8V
*C
4.7µF
O2
)
AIC1550
2
=
12
µ
F
13