Datasheet

C
10 10
C1 1.1 nF
2 R3 f 2 30 k 50 kHz
= = =
p ´ ´ p ´ W ´
C OUTB OUTB
BUCK CFB REF
2 f V C
R3
Gm K V
2 50 kHz 3.3 V 100 F
1 mS 4.16 S 0.8 V
31k
p ´ ´ ´
=
´ ´
p ´ ´ ´ m
´ ´
= = W
OUTB
OUTB OUTB
C OUTB
I
1.9 A
V I ESR 1.9 A 10 m 114 mV
4 f C 4 50 kHz 100 F
D
D = + D ´ = + ´ W =
´ ´ ´ ´ m
OUTB(Ripple)
OUTB(Ripple) OUTB(Ripple)
SW OUTB
I
0.4 A
V I ESR 0.4 A 10 m 5.3 mV
8 f C 8 400 kHz 100 F
= + ´ = + ´ W =
´ ´ ´ ´ m
OUTB
OUTB
SW OUTB
2 I
2 1.9 A
C 46 F
f V 400 kHz 0.12 V
´ D
´
» = = m
´ D ´
SENSE
60 mV
R 30 m
2 A
30 m
L 200 15 H
400 kHz
= = W
W
= ´ = m
OUTB
ON min
IN max SW
V
3.3 V
t 275 ns
V f 30 V 400 kHz
= = =
´ ´
R2
R1 R2
0.16
+
=
5 V
R1 R2
50 A
66 k+ =
m
= W
REF
OUTA
V
0.8 V
0.16
V 5 V
b = = =
TPS43330-Q1
TPS43332-Q1
www.ti.com SLVSA82E –MARCH 2011–REVISED APRIL 2013
Resistor Divider Selection for Setting V
OUTA
Voltage
Choose the divider current through R1 and R2 to be 50 µA. Then
and
Therefore, R2 = 16 kΩ and R1 = 84 kΩ.
BuckB Component Selection
Using the same method as for V
BuckA
produces the following parameters and components.
This is higher than the minimum duty cycle specified (100 ns typical).
∆I
ripple
current ≈ 0.4 A (approximately 20% of I
OUT max
)
Select an output capacitance C
OUTB
of 100 µF with low ESR in the range of 10 mΩ.
Assume f
C
= 50 kHz.
Use the standard value of R3 = 30 kΩ.
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