AAT1168-Q5-T AAT [Advanced Analog Technology, Inc.], AAT1168-Q5-T Datasheet - Page 14

• Manufacturer Part Number: AAT1168-Q5-T
• Description: TRIPLE-CHANNEL TFT LCD POWER SOLUTION WITH OPERATIONAL AMPLIFIERS
• Manufacturer: AAT [Advanced Analog Technology, Inc.]

DESIGN PROCEDURE
Boost Converter Design
Setting the Output Voltage and Selecting
the Lead Compensation Capacitor
The output voltage of boost converter is set by the
resistor divider from the output (V
center tap connected to the IN1. Where
converter feedback regulation voltage is 1.233V.
Choose R
calculate R
Inductor Selection
The minimum inductance value is selected to make
sure that the system operates in continuous conduction
mode (CCM) for high efficiency and to prevent EMI.
The equation of inductor used a parameter
the ratio of the inductor peak to peak ripple current to
the input DC current. The best trade-off between
voltage
permanent output current has a
0.5.
R
L
D 1
1
I fs
R
V
O
O
V
2
V
IN
O



D(1 D)
V
ripple
,
V
2
OUT1
1
IN1
(Figure 2) between 5.1k
to satisfy the following equation.
Figure 2. Feedback Circuit
2
,
1
of



transient
AAT1168/A/B
Advanced Analog Technology, Inc
output
OUT1
between 0.4 and
) to GND with the
V
–
to 51k
IN1
current
, the boost
Advanced Analog Technology, Inc. –
–
, which is
台 灣 類 比 科 技 股 份 有 限 公 司
and
and
Page 14 of 22
Version 1.00
The AAT1168 SW current limit (
saturation current rating (
and the inductor's DC current rating should exceed
For the best efficiency, choose an inductor with less
DC series resistance (
Example 1: In the typical application circuit (Figure 1)
the output load current is 300mA with 13.3V output
I
I
I
I
D
I
I
I
I
P
P
V
V
f
IN
( L
IN
LDC
O
LPEAK
LIM
LDC
S
DCR
DCR
IN
O
: Boost converter efficiency
: The ratio of the inductor peak to peak ripple current
=
: Duty cycle
peak
: Output load current
: Switching frequency
C6-K1.8L
: Input DC current
to the input DC current
: Input voltage
: Output voltage
3.9 H
6.8 H
I
10 H
: DC current rating of inductor
Lpeak
>
and
: Power loss of inductor series resistance
I
(1 D)
)
IN
I
: Inductor peak to peak ripple current
IN
MITSUMI Product-Max Height: 1.9mm
I



O
I
(1 D)
–
IN
I
I
O
LSAT
,
V
2
Table 1.Inductor Data List



IN
Lf
2
AAT1168/1168A/1168B
>
D
s
r
L
41 m
68 m
81 m
.
,
I
( L
r
L
peak
r ).
L
I
LSAT
)
DC CURRENT RATING
) should exceed
I
LIM
2.5A
2.2A
1.8A
) and inductor’
May 2008
I
( L
peak
I
IN
)
.
,