TPS2145, TPS2147

TPS2155, TPS2157

SLVS333 − AUGUST 2001

20

www.ti.com

APPLICATION INFORMATION

10

µF

0.1

µF

TPS2147

4.7

µF

0.1

µF

LDO_OUT

OUT1

EN1

OC1

OUT2

EN2

3.3 V

LDO

OC2

USB

Function

Controller

D+

D−

GND

5 V

1.5 k

Ω

VIN/SW1

SW2

5-V

Circuitry

External

5-V

Supply

4.7

µF

0.1

µF

Figure 19. TPS2147 USB Bus-Powered/Self-Powered Peripheral Application

DSP applications

Figure 20 shows the TPS2145 in a DSP application. DSPs use a 1.8-V core voltage and a 3.3-V I/O voltage.

In this type of application, the TPS2145 adjustable LDO is configured for a 1.8-V output specifically for the DSP

core voltage.

The additional 3.3-V circuitry is powered through switch 1 of the TPS2145 only after the DSP is up and running.

Switch 2 is used to provide power to additional circuitry operating from a different voltage source. This switch

is also controlled by the DSP.

Figures 21 thru 23 show the TPS2145 in various DSP applications using a supply voltage supervisor (SVS) chip

to control the enable for the 3.3 V powering up the DSP I/O circuitry.