Disable Analog Inputs

[Mahmoud Tolba]

Hello Forum,

We have designed a custom board, pretty much following the OSD3358-SM-RED reference design and PocketBeagle.

We plan to use the default Debian image of PocketBeagle.

In my design, I don’t use the Analog inputs so I followed the design guidelines and connected VREFP and VREFN to the AGND.

I noticed that you connected PMIC_MUX_OUT to AIN7.

My question is should I enable the analog inputs to monitor the PMIC_MUX_OUT? is it necessary to monitor the internal voltages or I can ignore it?

Waiting to hear from you.

Thanks..

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[Neeraj Dantu]

Mahmoud,

It is not necessary to connect the PMIC_MUX_OUT to AIN7. The reason that was done in the reference design was to have an option for an application level check on the power rails(mainly VSYS) that PMIC_MUX_OUT exposes(See section 8.3.8 Analog Multiplexer in TPS65217C datasheet: http://www.ti.com/lit/ds/symlink/tps65217.pdf).

The question of if you should monitor the power rails(please refer to the Analog Multiplexer section of the PMIC datasheet to see what power rials, the PMIC_MUX_OUT gives access to) depends on your system requirements. Is it a system, in which you would have to detect when there is a power rail failure on for example SYS_VOUT, and perform additional tasks to address it? If so, it is a good idea to have an application software check on power rail health.

Also, you do not need to use the ADC subsystem to monitor the health of the power rials. You can have external circuitry on the power rails you want to monitor, detect failure and trigger actions.

Neeraj

[Mahmoud Tolba]

Thanks Neeraj

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