TPS60500, TPS60501
TPS60502, TPS60503
SLVS391B − OCTOBER 2001 − REVISED FEBRUARY 2002
APPLICATION INFORMATION
DSP supply with sequencing
This application shows a power supply for a typical DSP. DSPs usually have core voltages in the 1-V to 2.5-V
range, whereas the voltage at the I/O-pins (I/O voltage) is typically 3.3 V to interface with external logic and
converters. Therefore, a power supply with two output voltages is required. The application works with an input
voltage in the range of 3.5 V to 6.5 V. The maximum output current is 150 mA on each output.
The supply is enabled by pulling the enable pin (EN of the TPS60503) to GND. The step-down charge pump
starts and its power good (PG) output goes high. This enables the LDO which powers the I/O lines and generates
a reset signal for the DSP. Figure 27 shows the timing diagram of the start-up/shutdown procedure.
VI/O
V(NOM)
VIT
t
TPS77133
VI
10 MΩ
1 MΩ
OUT
OUT
FB
EN RESET
GND
VIN
VIN
47 kΩ
V(CORE)
V(NOM)
VIT
3.3 V
10
µF†
VI/O
RS
‡
1
0
PG
1
V(CORE)
0
EN
1
td
td
t
TPS60503
VIN
47
µF
1 MΩ
EN
PG
FB
OUT
C1F+
C1F−
C2F+
C2F−
GND
1
µF
1
µF
RESET
td
t
1.5 V
10
µF†
ENABLE
GND
t
0
t
† Recommended value for stability, DSP may require higher capacitance.
‡ RS is the RESET output of the TPS77133.
Figure 27. DSP Supply With Sequencing
14
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