Datasheet

SS /TR
TPS5401
EN
PWRGD
SS/TR
EN
PWRGD
V
EN1
V
PWRGD1
V
OUT1
V
OUT2
V , V
EN1 EN2
V
OUT1
V
OUT2
EN
TPS54160
3
SS/TR
4
PWRGD
6
EN
TPS54160
3
SS/TR4
PWRGD
6
TPS5401
TPS5401
TPS5401
www.ti.com SLVSAB0 –DECEMBER 2010
DETAILED DESCRIPTION (continued)
Figure 30. Schematic for Sequential Start-Up Figure 31. Sequential Start-Up Using EN and
Sequence PWRGD
Figure 32. Schematic for Ratiometric Start-Up Figure 33. Ratiometric Start-Up Using Coupled
Sequence SS/TR Pins
Figure 32 shows a method for ratiometric start-up sequence by connecting the SS/TR pins together. The
regulator outputs ramp up and reach regulation at the same time. When calculating the slow-start time, the pullup
current source must be doubled in Equation 4. Figure 33 shows the results of Figure 32.
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