AM2432: MCU_OSC0_XI和MCU_OSC0_XO电平

Hello zhanglongc

Thank you for the query.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1322474/am623-mcu_osc0_xi-drive-level/5031483?tisearch=e2e-sitesearch&keymatch=oscillator%25252520AGC#5031483

You should configure the clock out on an SOC pin to measure the amplitude.

Regards,

Sreenivasa

Hello zhanglongc

zhanglongc said:

Crystal frequency: 25MHz
     Crystal load capacitance: 33pF

I just realized  the load cap you are using is 33 pF.

This may be out of the recommended range.

Regards,

Sreenivasa

Hi Kallikuppa Sreenivasa:

      Thank you for your reply,  i see the high frequency oscillator implemented in AM62x has an Automatic Gain Control (AGC) circuit that output voltage approximately 1V,so the AM243X AGC output voltege is 1V?It is very close to the amplitude of the clock signal I tested。

Hi Kallikuppa Sreenivasa:

  Thank you for your reply，I also realized  the load cap you are using is 33 pF is not inappropriate,but I  replace the load cap with 12pF(reference AM2434  EVM ),the AM243X AGC output voltege also is 1.05V.so  Is it okay for it to output 1V?

Hello zhanglongc

zhanglongc said:

Thank you for your reply,  i see the high frequency oscillator implemented in AM62x has an Automatic Gain Control (AGC) circuit that output voltage approximately 1V,so the AM243X AGC output voltege is 1V?It is very close to the amplitude of the clock signal I tested。

The oscillator implementation should be similar.

Regards,

Sreenivasa

Hello zhanglongc

zhanglongc said:

Thank you for your reply，I also realized  the load cap you are using is 33 pF is not inappropriate,but I  replace the load cap with 12pF(reference AM2434  EVM ),the AM243X AGC output voltege also is 1.05V.so  Is it okay for it to output 1V?

the cap depends on the crystal load.

Please follow the data sheet recommendations.

Be sure to consider the PCB stray capacitance as described in the data sheet.

Regards,

Sreenivasa

Hi Kallikuppa Sreenivasa.

      Thank for your reply.

      Base on your reply,i understand in AM2432 datasheet  section 7.7.3 (High-Frequency Oscillator (HFOSC) Electrical Characteristics)shown VIH＞0.65*VDDS_OSC is for Crystal oscillator, If the external clock uses crystals, SOC has no requirement for clock signal amplitude, Currently, our project uses a 25M crystal. I tested that the clock signal amplitude of MCU OSC0_XI and MCU OSC0_XO pins is 1V, which is also OK。

Hello zhanglongc

Thank you.

zhanglongc said:

If the external clock uses crystals, SOC has no requirement for clock signal amplitude, Currently, our project uses a 25M crystal. I tested that the clock signal amplitude of MCU OSC0_XI and MCU OSC0_XO pins is 1V, which is also OK。

This is correct.

Regards,

Sreenivasa