Help me understand this schematic about PROCHOT

[IamPritesh]

Can you anyone explain what should be the ideal voltage for PROCHOT according to this schematic.

I have no voltage on AD_IINP.
On U8801 I have 5V on pin 5 and 0.537 volt on pin 3. No output voltage.

Currently board is not triggering at all.

[mon2]

Re: Help me understand this schematic about PROCHOT

https://www.analog.com/en/design-cen...y/prochot.html

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

https://www.analog.com/en/design-cen...y/prochot.html

So under normal scenario it should be low ? Also I do not have AD_IINP voltage (The datasheet says it should be 20 times the difference between the two points of current sensing resistor. )

[mon2]

Re: Help me understand this schematic about PROCHOT

No, this is an active LOW signal since there is a '#' suffix.

In digital logic, a '#' suffix means the signal is considered active if logic low. So if low, the processor is running hot.

[mon2]

Re: Help me understand this schematic about PROCHOT

Remove all power. Measure the resistance across R8824.

If present, next check the resistance of R8823.

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

Remove all power. Measure the resistance across R8824.

If present, next check the resistance of R8823.

Thanks for helping me with this. here are the readings..

R8824 = 99.6K ohms if unsoldered from the board
R8824 = 13K~24K ohms while it is soldered to board

R8823 = 10.2 K ohms

[mon2]

Re: Help me understand this schematic about PROCHOT

Pin 3 has the correct voltage:

https://ohmslawcalculator.com/voltag...der-calculator

Use the above calculator to confirm. Use the values from the schematic.

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

Pin 3 has the correct voltage:

https://ohmslawcalculator.com/voltag...der-calculator

Use the above calculator to confirm. Use the values from the schematic.

yes you are right. So what should be the output on PIN 4 of U8801 ? If understand it should be 5v when we have a higher voltage on PIN 1 as compared to Pin 3 . But the fact is PIN 1 has no volt at all. Resistance to ground on Pin 1 of U8801 is 0.586.

[mon2]

Re: Help me understand this schematic about PROCHOT

Check if R0312 exists on your board.

Then measure the voltage to ground on each pin of R0312. This pull up must be present to pull the prochot# line to a logic high as the mosfet being driven by the comparator is OFF.

Effectively, this is an open drain or open collector driver.

There is a logic low if the mosfet closes when the gate voltage is high enough from the comparator.

Otherwise the prochot# line is floating so the external pull up resistor is required to define the open or floating logic state.

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

Check if R0312 exists on your board.

Then measure the voltage to ground on each pin of R0312. This pull up must be present to pull the prochot# line to a logic high as the mosfet being driven by the comparator is OFF.

Effectively, this is an open drain or open collector driver.

There is a logic low if the mosfet closes when the gate voltage is high enough from the comparator.

Otherwise the prochot# line is floating so the external pull up resistor is required to define the open or floating logic state.

R0312 has no voltage on either side .

[mon2]

Re: Help me understand this schematic about PROCHOT

Check if you have +1.0VO.

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

Check if you have +1.0VO.

Yes I do have +1.0VO on L8201

[mon2]

Re: Help me understand this schematic about PROCHOT

What is the voltage to ground of SUSB#_PWR ?

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

What is the voltage to ground of SUSB#_PWR ?

No voltage on SUSB#_PWR

Also +12VSUS is showing as 15V

[IamPritesh]

Re: Help me understand this schematic about PROCHOT

Any other pointers on this issue please. Really appreciate all the help that has been given so far.

[mon2]

Re: Help me understand this schematic about PROCHOT

From what I see, you are missing VCCIO.

VCCIO is based on +1VO which you have.

The load switch that passes on this rail to become VCCIO is triggered by SUSB#_PWR. This trigger is from the EC (as SUSB_EC# ) and this signal is missing.

This path is from page 92 of the linked schematic.

Review the basics, with the adapter connected, what are the voltage to ground of each coil. Are you missing any voltages on these coils?

You have a type C power supply to power this board?

Is it the original and with the proper power rating?

Do you have a usb c meter to review the current and voltage being selected by the logic board?