topic Re: i.MX287 VDDA output current in i.MX Processors

i.MX287 VDDA output current

jerry_fj_huang — Thu, 06 Feb 2020 03:19:55 GMT

Hi, NXP:

Recently, I want to use i.MX287 for basic system network because the chip has integral PMU reducing complexity.

However, one parameter needs to be clarified.

VDDA, which is the DDR source from i.MX287, can supply maximal 200mA for DDR2.

After measuring current through R31 on i.MX28 EVK, RMS value is under 200mA but peak value is around 560mA.

Ch1 is the voltage of VDDA_1V8, and Ch4 is the current through R31 on i.MX28 EVK.

What kind of value can stand for VDDA maximal output current? RMS, peak, average or else?

If this 200mA is RMS value, I can select W971G series which is same as i.MX287 EVK, and everything meets specification.

If this 200mA is peak value, I want to know the design concept of i.MX287 EVK. Why is this current value over specification?

Thank you.

Re: i.MX287 VDDA output current

igorpadykov — Thu, 06 Feb 2020 23:39:32 GMT

Hi Jerry

> I want to know the design concept of i.MX287 EVK. Why is this current value over specification?

Best regards
igor
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Re: i.MX287 VDDA output current

jerry_fj_huang — Fri, 07 Feb 2020 01:48:53 GMT

Hi, Igor:

I need more specific answers.

Do you mean the peak value of DDR load current should be under VDDA maximal output current and it is also acceptable even load current over the maximal value? And, what type of value is the maximal output current?

When we use a platform on new products, EVK is very important that circuit design is based on it.

I can't understand why NXP announced EVK even some parameters are out of specification.

So far, EVK works fine.

However, we need to design our application board.

Could you give suggestions how to modify EVK circuit to prevent possible failure caused due to out-of-specification parameters?

Re: i.MX287 VDDA output current

igorpadykov — Fri, 07 Feb 2020 11:09:43 GMT

Hi Jerry

you can use EVK currents as reliable and verified by nxp.

Best regards
igor

Re: i.MX287 VDDA output current

jerry_fj_huang — Mon, 10 Feb 2020 01:45:01 GMT

Hi, Igor:

Do you mean the EVK schematic circuit is reliable and verified?

Sorry, I did not make clear description.

What I really want to know is what I can use as reference design.

The peak value of DDR load current is out of the i.MX287 VDDA output maximal current, but the RMS value is within the maximal output.

I need to make sure there would be problem in the future, so clarify what type of the maximal output current is very important.

If there is no any confusion of EVK, then I will use EVK as reference design. Or, I think the EVK schematic circuit may have potential problems.

Re: i.MX287 VDDA output current

igorpadykov — Mon, 10 Feb 2020 05:37:22 GMT

EVK schematic has not any problems and was verified by NXP.

Best regards
igor