Datasheet

RIPPLE
C1
SW IN
RIPPLE
IN
SW C1
ESR RIPPLE ESR
I
V 10 mV
8 f C
I
C 194-μF
8 f V
V I R 40 mV
D = =
´ ´
= =
´ ´ D
D = ´ =
G/20
6 2
OUTx
C
SW
10
R3 7.2 k
85 10 A / V V
10 10
C1 22 nF
2 f R3 2 10 kHz 7.2 k
C1 22 nF
C2 223 pF
f 200 kHz
2 7.2 k 22 nF 1
2 R3 C1 1
2
2
-
= = W
´ ´
= = =
p ´ ´ p ´ ´ W
= = =
æ ö æ ö
p ´ W ´ ´ -
p ´ ´ ´ -
ç ÷
ç ÷
è ø
è ø
C C
LC ESR
10 kHz 10 kHz
G 40 log 20 log
3.1 kHz 6 kHz
f f
G 40 log 20 log
f f
15.9 dB= -
æ ö
æ ö
= ç ÷ -
ç ÷
ç ÷
ç ÷
è ø
è ø
æ ö æ ö
=
ç ÷ ç ÷
è ø è ø
OUTx
OUTx ESR OUTx
OUTx C
I
V R I
4 C f
2.5 A
0.04 2.5 A 0.19 V
4 660 F 10 kHz
D
+D = ´ D
´ ´
= W ´ + =
´ m ´
TPS43330-Q1
TPS43332-Q1
www.ti.com SLVSA82E –MARCH 2011–REVISED APRIL 2013
Output Ripple Voltage Due to Load Transients, ∆V
OUTx
Assume a bandwidth of f
C
= 10 kHz.
Because the boost converter is active only during brief events such as a cranking pulse, and the buck converters
are high-voltage tolerant, a higher excursion on the boost output may be tolerable in some cases. In such cases,
one can choose smaller components for the boost output.
Selection of Components for Type II Compensation
The required loop gain for unity-gain bandwidth (UGB) is
The boost-converter error amplifier (OTA) has a Gm that is proportional to the VBAT voltage. This allows a
constant loop response across the input-voltage range and makes it easier to compensate by removing the
dependency on V
BAT
.
Input Capacitor, C
IN
The input ripple required is lower than 50 mV.
Therefore, TI recommends 220 µF with 10-mΩ ESR.
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