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Original question:

TCAN1043A-Q1: VCC Undervoltage detection

TCAN1043A-Q1: VCC UV issues

Jiawei Hu1
Expert 5625 points
Part Number: TCAN1043A-Q1

Tool/software:

Hi team,

My customer BYD are using TCAN1043A-Q1 and they found low possibility of VCC undervoltage issue.

Background:

  • VBAT, VIO are powered normally, EN and STB are high. In this condition, if we power off VCC, the recover after 1s.
  • From datasheet, TCAN1043A will enter sleep mode.
  • After toggle nSTB, the CAN communication has low possibility failure.

Support need:

  • In this condition 'VBAT, VIO are powered normally, EN and STB are high. In this condition, if we power off VCC, the recover after 1s', TCAN1043A should enter into sleep mode, right?
  • How to move sleep mode into normal mode, just toggle nSTB, right?
  • Could you kindly check why this happen?

Thanks!

BR
Jiawei

  • 0
    TI__Genius 13862 points

    Hi Jiawei,

    Jiawei Hu1 said:
    In this condition 'VBAT, VIO are powered normally, EN and STB are high. In this condition, if we power off VCC, the recover after 1s', TCAN1043A should enter into sleep mode, right?

    This is correct. If VCC is under the UVCC range for time tUV (350ms max), then TCAN1043A will enter Sleep mode. 

    Jiawei Hu1 said:
    How to move sleep mode into normal mode, just toggle nSTB, right

    Yes. Underneath the state machine (Figure 7-4), footnote 4 describes that a low to high transition on nSTB is necessary to switch from Sleep to Normal mode in the event of a UVCC event.

    Jiawei Hu1 said:
    After toggle nSTB, the CAN communication has low possibility failure.

    Can you clarify what you mean by communication failure? Are they transmitting to TXD but not receiving the same signal on RXD?

    Can you ask the customer for a waveform probing RXD, TXD, EN, and nSTB pins?

    How long do they have nSTB low?

    Best,

    Ethan