V = 100 mV/Div (AC-Coupled)
IN
V
= 10 V/Div
PH
Time = 1 µs/Div
Figure 2-14. TPS5431 Input Ripple
2.9 Powering Up
The start-up waveform is shown in
. The top trace shows ENA, and the bottom trace shows Vout.
Initially, the output is inhibited by using a jumper at JP1 to tie EN to GND. When the jumper is removed, ENA
is released. When the ENA voltage reaches the enable-threshold voltage of 1.06 V, the start-up sequence
begins and the internal reference voltage begins to ramp up at the internally set rate towards 1.221 V and the
output voltage ramps up to the externally set value of 5 V. The start-up waveform is the same for both the
TPS5430EVM-173 and the TPS5431EVM-173.
ENA = 2 V/Div
V
= 2 V/Div
OUT
Time = 2 ms/Div
Figure 2-15. TPS5430 and TPS5431 Start-Up
Test Setup and Results
SLVU157A – MARCH 2006 – REVISED OCTOBER 2021
TPS5430 and TPS5431 Step-Down Converter Evaluation Module User's
Guide
11
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