• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 98 subscribers
  • Views 584 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM625: the boot mode buffer

user3895290
Prodigy 80 points
Part Number: AM625
Other Parts Discussed in Thread: TPS65219, SN74LVC244A

Hello TI

I am reviewing the design file (SPRR453.ZIP) for the SK-AM62-P1 EVM with TPS65219 PMIC.
The BOOT MODE SWITCHES (SW1, SW2) are currently pulled up to VCC3V3_TA.
The BOOT MODE BUFFERS (U73, U75) use SN74AVC8T245RHL to perform voltage level translation between VCC3V3_TA (VCCA) and VCC_3V3_SYS (VCCB).

Please provide information on the following:
(1) Is it possible to change the pull-up of BOOT MODE SWITCHES (SW1, SW2) to VCC_3V3_SYS?
(2) Could you explain the reason for using SN74AVC8T245RHL in the BOOT MODE BUFFERS (U73, U75)?
　　Additionally, is it feasible to use SN74LVC244A with VCC=VCC_3V3_SYS in the BOOT MODE BUFFERS?

Regards,
user3895290

  • +1
    TI__Guru**** 189039 points

    Hello user3895290

    Thank you for the query.

    I have the answers for the 2 question you asked. 

    user3895290 said:
    (1) Is it possible to change the pull-up of BOOT MODE SWITCHES (SW1, SW2) to VCC_3V3_SYS?

    Should be fine.

    user3895290 said:
    (2) Could you explain the reason for using SN74AVC8T245RHL in the BOOT MODE BUFFERS (U73, U75)?

     those are isolation buffers to ensure the sysboot pulls are controlling the level on the signals when the bootmode signals are latched (around the PORz_OUT rising edge).  Since bootmode signals are often used for other functions beyond reset and are connected to other device, they need to be isolated from other connected peripherals so that those peripherals do not conflict with the intended bootmode signal levels.

    ...

    Regards,

    Sreenivasa

  • 0
    TI__Guru**** 189039 points

    Hello user3895290

    Q2  explains the buffer query.  You should be able to use the below device but looks like we may not have tested to confirm.

    You could do a self-review  using  Logic & voltage translation  tab on TI.com or reach out to the PL for support.

    user3895290 said:
    Additionally, is it feasible to use SN74LVC244A with VCC=VCC_3V3_SYS in the BOOT MODE BUFFERS?

    Regards,

    Sreenivasa