Texas Instruments TPS54980EVM-022, Руководство пользователя

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Power Up and Down
2-10
Figure 2−12. Power Down With Tracking
VO I/O 500 mV/div
t − Time − 1 ms/div
VO Core 500 mV/div
The TPS54980EVM-022 EVM provides the ability to change the slew rate of
the output voltage of the core regulator by using jumper JP2 (see schematic
in Figure 4−1). If jumper JP2 is set so that R8 is connected in parallel to R7,
ratiometric power sequencing is implemented. For ratiometric sequencing, the
following condition must to be met: if R6 = 10 k
Ω
then R8 II R7 = (R7
×
0.891)/(V
I/O
− 0.891). In this case, the I/O and core voltages reach their
nominal values at the same time. The waveforms for ratiometric power up and
down are shown in Figure 2−13 and Figure 2−14.
Figure 2−13. Power Up With Ratiometric Sequencing
VO I/O 500 mV/div
t − Time − 500
µ
s/div
VO Core 500 mV/div