Datasheet

Start-Up
2-10
2.10 Start-Up
Figure 2–12 shows the start-up voltage waveform of the TPS54310 EVM with
C1 left open. The input voltage is displayed on channel 3, the output voltage
on channel 1, and the power good signal on channel 2. Once the input voltage
rises above the 2.9-V start-up threshold, the output voltage begins to rise
linearly to 3.3 V in 3.6 ms. When the output voltage has reached its final value,
the open-drain power good signal rises to a high state. The start-up time can
be extended by using an external slow-start capacitor, C1. To program a
specific slow start time, see Section 1.3.4 Slow Start.
The shorting jumper on J2 should not be used to enable the EVM, as this may
cause excessive voltage transients on the SS/ENA pin. Use an external
enable signal instead of the J2 jumper.
Figure 2–12. Measured Start-Up Waveforms
V
I
(2 V/div)
V
O
(2 V/div)
V
(PWRGD)
(5 V/div)
1 ms/div
1
3
2