Datasheet

ESR ESR
OUTx ESR
ESR
LC
OUTx
1
f Hz, assume R = 40 m
2 C R
1
f 6 kHz
2 660 F 0.04
1 1
f 3.1 kHz
2 L C 2 4 H 660 F
=
= =
= W
p ´ ´
=
p ´ m ´ W
=
p ´ ´ p´ m ´ m
RHP
LC
BAT min
INmax
OUTx
2
2
INmax
OUTx
BAT min
OUTx min
4 H
f
f
10
V
10
2 I L
2 L C
10 I
10 6.3 A
C L
V 5 V
C 635 F
³ ´ m
£
£
p´ ´
p´ ´
æ ö
´
æ ö
´
ç ÷ ´ =
ç ÷
ç ÷
è ø
è ø
³ m
TPS43330-Q1
TPS43332-Q1
SLVSA82E –MARCH 2011–REVISED APRIL 2013 www.ti.com
Output Capacitor, C
OUTx
To ensure stability, choose output capacitor C
OUTx
such that
Select C
OUTx
= 680 µF.
This capacitor is usually aluminum electrolytic with ESR in the tens of milliohms. ESR in this range is good for
loop stability, because it provides a phase boost. The output filter components, L and C, create a double pole
(180-degree phase shift) at a frequency f
LC
and the ESR of the output capacitor R
ESR
creates a zero for the
modulator at frequency f
ESR
. One can determine these frequencies by the following:
This satisfies f
LC
≤ 0.1 f
RHP
.
Bandwidth of Boost Converter, f
C
Use the following guidelines to set the frequency poles, zeroes, and crossover values for the trade-off between
stability and transient response:
f
LC
< f
ESR
< f
C
< f
RHP Zero
f
C
< f
RHP Zero
/ 3
f
C
< f
SW
/ 6
f
LC
< f
C
/ 3
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