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DP83826E: Power-on and Reset Release Timing

g.f.
Guru 15520 points
Part Number: DP83826E
Other Parts Discussed in Thread: AM3356

Hi,

I have questions about power-on and reset release timing of DP83826 and AM3356.

How should I consider the power-on timing and reset signal release timing for DP83826 and AM3356(MPU)?

Q1.
Does DP83826 need to be power-on after MPU have been power-on and stable?
Or no power-on timing need to be consider between PHY and MPU?

Q2.
In general, is the DP83826 supplied from the same power supply as the MCU at the same time,
and is the reset release of the DP83826 done from the MCU?
If so, at what timing should the reset of the DP83826 be released from the MCU?

best regards,
g.f.

  • 0
    TI__Mastermind 37180 points

    Hi G.F,

    In an ideal world, the powerup requirements of the PHY are independent of the MPU. However, due to the PHY's strap pins (and potentially its clock system) being heavily compacted by SoC, it is best practice to hold the PHY in reset by MCU until the SoC is completely initialized, and then PHY gets its reset deasserted. The key point I would like to stress is that SoC should not impact PHYs key subsystems (like strapping values) in order for PHY to be booted up correctly.

    Please check out PHY power up timing specifications in datasheet for more information.

    Sincerely,

    Gerome