Datasheet
SLVS324A − JULY 2001 REVISED NOVEMBER 2004
15
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APPLICATION INFORMATION
Table 4. Measurement Results on the TPS60400 (Typical)
V
I
[V]
I
O(2)
[mA]
C
I
[µF]
C
(fly)
[µF]
C
O
[µF]
L
P
[µH]
C
P
[µF]
BW = 500 MH
z
V
POUT
BW = 20 MHz
V
POUT
V
POUT
VACeff [mV]
I
[V]
O(2)
[mA]
CERAMIC CERAMIC CERAMIC
P
[
µ
H]
CERAMIC
V
POUT
V
P−P
[mV]
V
POUT
V
P−P
[mV]
POUT
VACeff [mV]
5 60 1 1 1 320 240 65
5 60 1 1 2.2 120 240 32
5 60 1 1 1 0.1 (X7R) 260 200 58
5 60 1 1 1 0.1 0.1 (X7R) 220 200 60
5 60 1 1 2.2 0.1 0.1 (X7R) 120 100 30
5 60 1 1 10 0.1 0.1 (X7R) 50 28 8
rail splitter
TPS60400
OUT C1+
IN
C1− GND
1
2
3
5
4
C
(fly)
1 µF
C
O
1 µF
C
I
1 µF
V
O
= V
I
/2
GND
V
I
GND
C3
1 µF
Figure 26. TPS60400 as a High-Efficiency Rail Splitter
A switched-capacitor voltage inverter can be configured as a high efficiency rail-splitter. This circuit provides a
bipolar power supply that is useful in battery powered systems to supply dual-rail ICs, like operational amplifiers.
Moreover, the SOT23-5 package and associated components require very little board space.
After power is applied, the flying capacitor (C
(fly)
) connects alternately across the output capacitors C
3
and C
O
.
This equalizes the voltage on those capacitors and draws current from V
I
to V
O
as required to maintain the
output at 1/2 V
I
.
The maximum input voltage between V
I
and GND in the schematic (or between IN and OUT at the device itself)
must not exceed 6.5 V.