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S001

TPS2500, TPS2501

www.ti.com

SLVS886C – OCTOBER 2008 – REVISED AUGUST 2010

APPLICATION INFORMATION

Step-by-Step Design Procedure

The following design procedure provides an example for selecting component values for the TPS2500.

The following design parameters are needed as inputs to the design process.

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Input voltage range

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Output voltage on AUX

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Input ripple voltage

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Output ripple voltage on AUX

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Output current rating of AUX rail

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Output current rating of USB rail

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Nominal efficiency target

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Operating frequency

A power inductor, input and output filter capacitors, and current-limit threshold resistor are the only external

components required to complete the TPS2500 boost-converter design. The input ripple voltage, AUX ripple

voltage, and total output current affect the selection of these components.

This design example assumes the following input specifications.

PARAMETER

EXAMPLE VALUE

Input voltage range (VIN)

2.7 V to 4.2 V

AUX voltage (VAUX)

5.1 V (internally fixed)

Input ripple voltage (

ΔVIN)

15 mV

AUX ripple voltage (

ΔVAUX)

50 mV

AUX current (IAUX )

0.5 A

USB current (IUSB )

0.5 A

Total current (ITOTAL = IAUX + IUSB)

1 A

Efficiency target, nominal

90%

Switching frequency (f)

1 MHz

Figure 22. Reference Schematic

Switching Frequency

The switching frequency of the TPS2500 is internally fixed at 1 MHz.

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Product Folder Link(s): TPS2500 TPS2501