I.MX6UL + PF3001A7 POR_n behaviour when placing Scope or Multimeter Probe

[nachodiz]

Dear All

I.MX6 Ultralite pullups PORn to +SNVS Internally with weak 100k Pullup Resistor
Our PMIC PF3001A7 PORn output its open drain
So the SoC pullups this line

If i place the Agilent U1257B multimeter or Scope probes over SoC POR_n Testpoint the Soc Resets!

I also Added external 10k pullup to SNVS but This till ocurs

Any idea?

Perhaps Probe Capacitance ...





King Regards

[Pavel]

Is there problem for using this multimeter on NXP i.MX6 board?

Is there a capacitor on POR_N on your board?

NXP board contains 100n capacitor of the POR_n.

Have a great day,
Pavel Chubakov

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[nachodiz]

Dear Sir

Every time y connect multimeter probe to Testpoint I always connect the other probe to solid and robust Board GND



 

[Pavel]

This behavior shows that this problem concerns to power supply of your Agilent U1252B and power supply of your i.MX6 board.

It looks like that there is a static voltage between your Agilent and your i.mx6 board.

If multimeter is connected before power on, there is no static voltage.

If multimeter is connected after power on, this static voltage produces reset of the i.mx6.

Connect the GND of your multimer and your i.mx6 board.

Have a great day,
Pavel Chubakov

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[nachodiz]

Please anbody can help me with this ?

Maybe SNVS is high impedance because it has too low output current capabilities

[Pavel]

It look like that your Agilent multimeter is broken or this multimeter is not switched for voltage measurement.

Check setting of your multimeter.

Agilent multimeters usually provide impedance approximately 10 MOhm for 5 V~1000 V ranges.

Similar input impedance could not assert PORESET on the i.MX6.

Test your board using the following:

Connect your multimeter to the board and after that switch on the power supply of the board.

Have a great day,
Pavel Chubakov

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Note: If this post answers your question, please click the Correct Answer button. Thank you!
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[nachodiz]

Ok I will check

We´ve purchased this Agilent U1252B Last Week

So I think that it´s not broken :smileyhappy:

I detected the following behaviour :

- If i place multimeter probes between GND and TP16 (PORn Testpoint) when system is  OFF and then I power on the board it boots properly

- If i place multimeter probes between GND and TP16 when system is ON it reboots, but if I keep the probe over TP16 it continues working

- If i place multimeter probes between GND and TP16 when system is ON it reboots, but if I keep the probe over TP16 it continues working, but if i remove probes and place probes again, system reboots!