Datasheet

 
 
SLVS333 − AUGUST 2001
20
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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 kΩ
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.