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APPLICATION INFORMATION

C2

RT

SS/ENA

VBIAS

PWRGD

VSENSE

1

2

3

4

5

6

7

9

VIN

PH

BOOT

PGND

PGND

PGND

PwrPAD

U1

TPS54312PWP

1

2

VO

GND

J3

C7

0.047

µF

R1

10 k

Ω

C11

1000 pF

1

J1

2

1

VI

GND

+

1

Optional

71.5 k

Ω

L1

5.2

µH

R7

8

10

11

12

13

14

15

16

17

18

19

20

AGND

NC

PH

PH

PH

PH

FSEL

VIN

VIN

C8

10

µF

C3

0.1

µF

+

C9

470

µF

4 V

PWRGD

INPUT VOLTAGE

FEEDBACK CIRCUIT

OPERATING FREQUENCY

R +

500 kHz

Switching Frequency

100 kW

(1)

OUTPUT FILTER

TPS54311-EP, TPS54312-EP,

TPS54313-EP, TPS54314-EP,

TPS54315-EP, TPS54316-EP

SGLS376A – FEBRUARY 2007 – REVISED MARCH 2007

Figure 10 shows the schematic diagram for a typical TPS54314 application. The TPS54314 (U1) can provide up

to 3 A of output current at a nominal output voltage of 1.8 V. For proper thermal performance, the PowerPAD

underneath the TPS54314 integrated circuit needs to be soldered to the printed circuit board.

Figure 10. TPS54314 Schematic

The input to the circuit is a nominal 5 VDC, applied at J1. The optional input filter (C2) is a 220-

µF POSCAP

capacitor, with a maximum allowable ripple current of 3 A. C8 is the decoupling capacitor for the TPS54314 and

must be located as close to the device as possible.

The output voltage of the converter is fed directly into the VSENSE pin of the TPS54314. The TPS54314 is

internally compensated to provide stability of the output under varying line and load conditions.

In the application circuit, a 700 kHz operating frequency is selected by leaving FSEL open and connecting a

71.5 k

Ω resistor between the RT pin and AGND. Different operating frequencies may be selected by varying the

value of R3 using equation 1:

Alternately, preset operating frequencies of 350 kHz or 550 kHz my be selected by leaving RT open and

connecting the FSEL pin to AGND or VIN, respectively.

The output filter is composed of a 5.2-

µH inductor and 470-µF capacitor. The inductor is a low dc resistance

(16-m

Ω) 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.

8

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