TPS54240_15 Datasheet, PDF (19/56 Pages) Texas Instruments – TPS54240 3.5-V to 42-V Step-Down DC - DC Converter With Eco-Mode™

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Feature Description (continued)
TPS54240
SLVSAA6B – APRIL 2010 – REVISED NOVEMBER 2014
TPS5412640
3 EN
4 SS/TR
6 PWRGD
TTPPSS554412640
3 EN
4 SS/TR
6 PWRGD
Figure 32. Schematic for Ratio-metric Startup Sequence
EN1, EN2
VOUT1
VOUT2
Figure 33. Ratio-metric Startup Using Coupled SS/TR Pins
Figure 32 shows a method for ratio-metric start up sequence by connecting the SS/TR pins together. The
regulator outputs will ramp up and reach regulation at the same time. When calculating the slow-start time, the
pullup current source must be doubled in Equation 6. Figure 33 shows the results of Figure 32.
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