Datasheet

 
 
SLVS391B − OCTOBER 2001 − REVISED FEBRUARY 2002
16
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APPLICATION INFORMATION
power supply with dynamic voltage scaling (continued)
General requirements for the application:
D Output voltage1 (DSP core): 1.5 V ±0.08 V
D Output voltage 2 (DSP core): 1.1 V +0.1 V –0.05 V
D Input voltage: 3 V to 3.3 V
D Output current: 150 mA (10R load)
C1F
1 µF
86
C1F− C1F+
C2F
1 µF
34
C2F− C2F+
7
OUT
10
FB
C
o
10 µF
2
PG
R1
5
VIN
1
EN
GND
9
OFF/ON
C
i
2.2 µF
TPS60500
Input
3.3 V
R2
R3
C
(ff)
150 pF
R4
T1
BSS138
R5
330 kΩ
C6
470 pF
1.5 V / 1.1 V
150 mA
DVS in
Figure 29. Dynamic Voltage Scaling Application
To keep current through the adjustment resistor network as low as possible, the resistors are calculated to:
R3 +
V
FB
V
out1
*V
FB
R2
V
out1
adjusted by R2 and R3
V
out1
= 1.1 V,
R2 = 180 kΩ,
V
ref
= 0.80 V,
→R3 = 470 kΩ
V
out2
adjusted by R2 and Rx = R3||R4
V
out2
= 1.5 V,
→Rx = 206 kΩ
Rx +
V
FB
R2
ǒ
V
out2
* V
FB
Ǔ
→R4 = 360 kΩ
³ R4 +
1
1
Rx
*
1
R3
1
Rx
+
1
R3
)
1
R4
(1)
(2)
(3)