Texas Instruments TPS54A20, User Manual, Page: 12 / 25

Time = 2 msec / div
EN = 1 V / div
V = 500 mV / div
O
V = 10=0 V / div
IN
Time = 2 msec / div
EN = 1 V / div
V = 500 mV / div
O
V = 10=0 V / div
IN
Test Setup and Results
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12 SLVUAM8A – December 2015 – Revised March 2019
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TPS54A20EVM-770, 10-A, SWIFT™ regulator evaluation module
2.9 Powering Up
Figure 13 and Figure 14 show the start-up waveforms for the TPS54A20EVM-770. In Figure 13 , the output
voltage ramps up as soon as the input voltage reaches the UVLO threshold as set by the R2 and R3
resistor divider network. In
Figure 14 , the input voltage is initially applied and the output is inhibited by
using a jumper at J2 to tie EN to GND. When the jumper is removed, EN is released. When the EN
voltage reaches the enable-threshold voltage, the start-up sequence begins and the output voltage ramps
up to the externally set value of 1.2 V. The input voltage for these plots is 12 V and the load is 1
Ω
.
Figure 13. TPS54A20EVM-770 Start-Up Relative to V
IN
Figure 14. TPS54A20EVM-770 Start-Up Relative to Enable