5

C3

+

RT

SYNC

SS/ENA

VBIAS

VIN

VIN

VIN

PGND

PGND

PGND

PwrPd

AGND

VSENSE

COMP

PWRGD

BOOT

PH

PH

PH

PH

PH

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

4

3

2

1

VIN (4.5 − 5.5 V)

C1

10 µF

R7

10 k

U2

TPS54110PWP

PWRGD

R4

71.5 k

C5

.047 µF

C4

0.1 µF

C9

10 µF

21

0.047 µF

R3

19.1 k

C7

33 pF

C6

2700 pF

C8

2200 pF

R5

2.05 k

R1

10.7 k

R2

3.92 k

1

2

L1

6.8 µH

3.3 V at 1.5 A

C2

100 µF

s(kHz)

100

500kHz

RT(k ) =

¦

´

W

TPS54110

SLVS500C

– DECEMBER 2003 – REVISED FEBRUARY 2011

www.ti.com

APPLICATION INFORMATION

Figure 9 shows the schematic diagram for a typical TPS54110 application. The TPS54110 can provide up to

1.5 A of output current at a nominal output voltage of 3.3 V. For proper thermal performance, the exposed

PowerPAD underneath the device must be soldered down to the printed-circuit board.

Figure 9. Application Schematic

Design Procedure

The following design procedure can be used to select component values for the TPS54110. Alternately, the

SWIFT Designer Software can be used to generate a complete design. The SWIFT Designer Software uses an

iterative design procedure to access a comprehensive database of components when generating a design. This

section presents a simplified discussion of the design process.

Design Parameters

The required parameters to begin the design process and values for this design example are listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

4.5 to 5.5 V

Output voltage

3.3 V

Input ripple voltage

100 mV

Output ripple voltage

30 mV

Output current rating

1.5 A

Operating frequency

700 kHz

As an additional constraint, the design is set up to be small size and low component height.

Switching Frequency

The switching frequency is set within the range of 280 kHz to 700 kHz by connecting a resistor from the RT pin

to AGND. Equation 1 is used to determine the proper RT value.

(1)

In this example, the timing-resistor value chosen for R4 is 71.5 k

Ω, setting the switching frequency to 700 kHz.

8

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