Advanced Analog Technology, Inc.
April 2007
AAT1164/AAT1164B/AAT1164C
∆I
Lpeak-peak
DESIGN PROCEDURE
k =
I
IN
Boost Converter Design
: Boost converter efficiency
η
Setting the Output Voltage and Selecting
the Lead Compensation Capacitor
k: The ratio of the inductor peak to peak ripple current to
the input DC current
The output voltage of boost converter is set by the
resistor divider from the output (VOUT1) to GND with the
center tap connected to IN1, where VIN1, the boost
converter feedback regulation voltage is 1.233V,
Choose R2 (Figure 2) between 5.1kΩ to 51kΩ and
calculate R1 to satisfy the following equation.
VIN: Input voltage
VO: Output voltage
IO: Output load current
fS: Switching frequency
D: Duty cycle
∆ILpeak–peak: Inductor peak to peak ripple current
IIN: Input DC current
2
VOUT1
R1 = R
−1
V
IN1
The AAT1164 SW current limit ( LIM ) and inductor’s
I
saturation current rating ( LSAT ) should exceed IL(peak)
I
,
VOUT1
and the inductor's DC current rating should exceed IIN.
For the best efficiency, choose an inductor with less DC
series resistance (rL ).
VREF
IN1
R1
EO
gm
24
23
VIN1
and
>
IL(peak)
I
RC
CC
I
LSAT
LIM
R2
CP
I >I
LDC IN
V D
IN
,
I
= I
+
L(peak)
IN
GND
2Lf
S
GND
IO
η(1− D)
,
I
=
IN
Figure 2. Feedback Circuit
2
I
O
Inductor Selection
P
≈
r
L
DCR
η(1− D)
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 uses a parameter k, which is the
ratio of the inductor peak to peak ripple current to the
input DC current. The best trade-off between voltage
ripple of transient output current and permanent output
ILDC: DC current rating of inductor
PDCR: Power loss of inductor series resistance
Table 1. Inductor Data List
rL
C6-K1.8L
DC CURRENT RATING
3.9
6.8
µ
µ
H
H
2.5A
41m
Ω
current has a k between 0.4 and 0.5.
ηV
68m
Ω
Ω
2.2A
1.8A
2
O
,
D(1−D)
L ≥
10µH
81m
kI f
O S
MITSUMI Product-Max Height:1.9mm
V
IN
D = 1−
V
O
,
–
–
–
Advanced Analog Technology, Inc
Version 1.00
. –
Page 15 of 24
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