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TMS570LS3134: TPS65381A-Q1 connection with Hercules

Koichiro Tashiro
Mastermind 22350 points
Part Number: TMS570LS3134

Hi,

TPS65381 NRES pin is supposed to be directly connected to Hercules nPORRST pin.

According to datasheet, NRES pin is internally pull-up with ~4.5kOhm.
nPORRST pin is internally pull-down with 100uA.
So the signal state is around 3V due to balancing of these pulls.

Hercules VIH is max. 2V, so there should be no issue, but my customer wants to confirm why these pins are designed so.

Thanks and regards,
KoT

  • 0
    TI__Guru**** 192486 points
    Hi KoT,

    There is no VIH for nPORRST.

    When VCCIO>2.5V, the VIL of nPORRST is 0.2*VCCIO. For example, if VCCIO=3.3V, the VIL is 0.66V.
    When VCCIO<2.5V, the VIL of nPORRST is 0.5V

    When the input voltage is bigger than VIL, the PORRST is released or de-asserted.