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menatwork

menatwork

New member
Just stop work.
No water damage or something like that.
Have green Light but won't turn on.


PPBUS_G3H: 12.62V
PP3V42_G3H: 3.497
PPVRTC_G3H: 3.337
PP5V_S5: 5.01V
PP3V3_S5: 0V
PP5V_S3: 0V
PP3V3_S3: 0V
PM_SLP_S4: 0V
PM_SLP_S3: 0V

U7201 Pins:

1: 0V
2: 0V
3: 0
4: 0
5. 0
6. 1.98 V
7. 0
8. 0
9. 0
10.1.98
11.0
12.3.42 - SMC_PM_G2_EN
13. 3.42V
14. 5V
15. 1.98
16. 0
17. 0
18. 0V
19. 1.98V
20. 0V
21. 3.42V
22. 5.64
23. 12.56V
24. 0 V
 
Last edited:
larossmann

larossmann

Administrator
Staff member
I am going to oversimplify. 99% of the time, this will be one of four things.

1) PP3V3_S5 is shorted to ground.
2) The IC responsible for creating PP3V3_S5 is not receiving power on its VIN/VCC/VDD/voltage input pin.
3) The IC responsible for creating PP3V3_S5 is bad.
4) The IC responsible for creating PP3V3_S5 is not being told to create PP3V3_S5.

Looking at the page, on the side where PP3V3_S5 is created, we have a pin called "EN"... let's guess. P3V3S5_EN is the name of the signal present at the ENable pin. Let's guess what P3V3S5_EN stands for. P3V3S5_EN.. as in, ENable PP3V3_S5. According to your measurements, we have 3.4v there - so the IC responsible for creating PP3V3_S5 is being told to turn on. This crosses out #4 as a possible problem.

TPS51980 is an electronic chip, and like all electronic chips, to do something it wants power. What feeds it power? Datasheet says it gets power to do what it does on the VIN pin. VIN, as in, voltage in, as in, power going into it so it can turn on is provided on pin 23. Pin 23 is getting 12.56v, which is a healthy PPBUS_G3H power rail. So, the chip responsible for creating PP3V3_S5 is receiving the power it needs to turn on. This crosses out #2.

So this leaves either #1, or #3. I would measure the resistance to ground on PP3V3_S5. If the resistance is very low in contrast to what you get on a donor board; something is shorted to ground. However, if the resistance to ground on PP3V3_S5 is high, then, this would leave #3 as the winning possibility; TPS51980 is bad.

Page 60, 61, then 69-75 in the homework document I gave you will cover this. Tell me you didn't delete it!
 
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