TPS72101, TPS72115

TPS72116, TPS72118

SLVS352B – DECEMBER 2001 – REVISED MAY 2002

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8

TPS72115

1.8 V

1.5 V

Boost Converter

3.3 V

1.8 V – 3 V

VIO

VCORE

DSP or

Controller

Two AAA

Batteries

Figure 17. Dual Supply Application Circuit

EXTERNAL CAPACITOR REQUIREMENTS

A 0.1-

µF ceramic bypass capacitor is required on both the input and output for stability. Larger capacitors improve transient

response, noise rejection, and ripple rejection. A higher value electrolytic input capacitor may be necessary if large, fast

rise time load transient are anticipated, and/or there is significant input resistance from the device to the input power supply.

POWER DISSIPATION AND JUNCTION TEMPERATURE

Specified regulator operation is assured to a junction temperature of 125

°C; the maximum junction temperature allowable

without damaging the device is 150

°C. This restriction limits the power dissipation the regulator can handle in any given

application. To ensure the junction temperature is within acceptable limits, calculate the maximum allowable dissipation,

The maximum-power-dissipation limit is determined using the following equation:

P

D(max) +

T

J

max

* T

A

RqJA

Where:

table.

The regulator dissipation is calculated using:

P

D +

V

I *

V

O

I

O

Power dissipation resulting from quiescent current is negligible.