AMIC110: AMIC ICE schematics

Thomas Hecht

Part Number: AMIC110
Other Parts Discussed in Thread: SN74LVC2G66

Hi there

Since I also want to connect two PHYS for Ethercat to the AMIC110, I looked at the circuit and the software for the EVAL board. I do not quite understand the purpose of U10 (SN74LVC2G66). After configuring the PHYs and two AMIC pins as input, this IC will switch the RX_CLK and the PHY_LED1. Why is that necessary, can't the AMIC boot from the SPI first, then confirure the two AMIC pins
as inputs (for RX_CLK and PHY_LED1) and then finally release the PHY from the reset? Can't U10 be omited in that case?

best regards

Thomas

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Hi,

The purpose of U10 is to isolate the RX_CLK and PHY_LED1 at reset release time, so that the SYSBOOT values do not get overridden accidentally by these external signals. U8 and U9 serve the same purpose.

0 Thomas Hecht over 6 years ago in reply to Biser Gatchev-XID

Expert 1080 points

Hello Biser,

Thank you for your prompt reply.

U10 only applies to SYSBOOT (15) and SYSBOOT (12), both should have the value 0 (boot). If the PHY is held in reset (guaranteed by pulldown R56 and R69 and AMIC Pin U12 / R12 low during reset), the signal PHY1_LED1 = HiZ and the signal RX_CLK = PD so that driver U9 can safely set the pins of the AMIC to 0 (SYSBOOT(15) und SYSBOOT(12) ).

Would you also see it that way?

Best regards

Thomas

0 Biser Gatchev-XID over 6 years ago in reply to Thomas Hecht

TI__Guru**** 393215 points

It's actually SYSBOOT[14], but otherwise yes, it does seem that U10 is redundant. Since EVM designs are always done at a very early stage, the designers may have placed it as a precaution. Actually you can safely remove it only with SYSBOOT[14] selected low. If SYSBOOT[14] is selected high there will be a conflict.

0 Thomas Hecht over 6 years ago in reply to Biser Gatchev-XID

Expert 1080 points

Thank you verry much

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AMIC110: AMIC ICE schematics