Datasheet
TPS54611, TPS54612
TPS54613, TPS54614
TPS54615, TPS54616
SLVS400C − AUGUST 2001 − REVISED APRIL 2005
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8
APPLICATION INFORMATION
Figure 10 shows the schematic diagram for a typical
TPS54614 application. The TPS54614 (U1) can provide
greater than 6 A of output current at a nominal output
voltage of 1.8 V. For proper operation, the exposed thermal
PowerPAD underneath the integrated circuit package
needs to be soldered to the printed-circuit board.
13
12
7
8
6
BOOT
5
9
10
11
14
15
16
17
18
PH
PH
PH
PH
PH
PH
PH
PH
PH
19
PGND
PGND
PGND
PGND
PGND
PwrPad
AGND
NC
RT
SS/ENA
VIN
20
22
24
VBIAS
27
26
4
2
1
0.047 µF
7.2 µH
680 µF
V
O
1.8 V
10 kΩ
Enable
0.1 µF
V
I
3 V − 6 V
21
23
28
25
3
10 µF
220 µF
VIN
VIN
VIN
VIN
VSENSE
PWRGD
FSEL
PwrGood
C
SS
Figure 10. Application Circuit
COMPONENT SELECTION
The values for the components used in this design
example were selected using the SWIFT designer
software tool. SWIFT designer provides a complete design
environment for developing dc-dc converters using the
TPS54614, or other devices in the SWIFT product family.
Additional design information is available at www.ti.com.
INPUT FILTER
The input to the circuit is a nominal 3.3 VDC or 5 VDC. The
input filter is a 220-µF POSCAP capacitor, with a
maximum allowable ripple current of 3 A. A 10-µF ceramic
capacitor for the TPS54614 is required, and must be
located as close as possible to the device.
FEEDBACK CIRCUIT
The output voltage of the converter is fed directly into the
VSENSE pin of the TPS54614. The TPS54614 is
internally compensated to provide stability of the output
under varying line and load conditions.
OPERATING FREQUENCY
In the application circuit, 350 kHz operation is selected by
leaving FSEL open. Different operating frequencies can
be selected by connecting a resistor between RT pin and
AGND. Choose the value of R using Equation 1 for the
desired operating frequency:
R +
500 kHz
SwitchingFrequency
100 kW
Alternately, a preset operating frequency of 550 kHz can
be selected by leaving RT open and connecting the FSEL
pin to V
I
.
OUTPUT FILTER
The output filter is composed of a 5.2-µH inductor and a
470-µF capacitor. The inductor is low dc resistance
(16-mΩ) type, Sumida CDRH104R−5R2. The capacitor
used is a 4-V POSCAP with a maximum ESR of 40 mΩ.
The output filter components work with the internal
compensation network to provide a stable closed loop
response for the converter.
(1)