Dell Latitude E7280 no power from power adapter

[RethoricalCheese]

It works fine on battery but doesn't get powered from USB-C nor barrel jack.
19.5V gets up to Q905 pin 2 but not past that.


PU901 (ISL88738) voltages

bat+ac bat ac
1 CSON 6.43 6.43 0.04
2 CSOP 6.42 6.43 0.04
3 VSYS 6.42 6.42 0.04
4 BOOT2 0.00 0.00 0.00
5 UGATE2 0.00 0.00 0.00
6 PHASE2 0.00 0.00 0.00
7 LGATE2 0.00 0.00 0.00
8 VDDP 0.00 0.00 0.00

9 LGATE1 0.00 0.00 0.00
10 PHASE1 0.00 0.00 0.00
11 UGATE1 0.00 0.00 0.00
12 BOOT1 0.00 0.00 0.00
13 ASGATE 18.77 0.00 18.77
14 CSIN 19.63 0.15 19.63
15 CSIP 19.63 0.14 19.63
16 ADP 19.63 0.14 19.63

17 DCIN 19.58 6.20 19.58
18 VDD 0.00 0.00 0.00
19 ACIN 3.32 0.02 3.32
20 OTGEN/CMIN 0.00 0.00 0.00
21 SDA 0.00 0.00 0.00
22 SCL 0.00 0.00 0.00
23 PROCHOT# 0.00 0.00 0.00
24 ACOK 0.00 0.00 0.00

25 BATGONE 0.00 0.00 0.00
26 OTGPG/CMOUT 0.00 0.00 0.00
27 PROG 0.00 0.00 0.00
28 CMOP 0.00 0.00 0.00
29 AMON/BMON 0.00 0.00 0.00
30 PSYS 0.00 0.00 0.00
31 VBAT 6.95 6.95 0.06
32 BGATE 5.78 5.78 0.00


Is it faulty PU901 or what else might cause it to think there is something wrong with power input?

[piernov]

Re: Dell Latitude E7280 no power from power adapter

I think the issue is with VDD/VDDP, they should most likely be around 5V on AC (with DCIN and maybe ACIN and ADP present), make sure there's no short to ground there, otherwise might be dead charger IC.

[RethoricalCheese]

Re: Dell Latitude E7280 no power from power adapter

Yeah, thanks! For some reason I read Vss not Vdd, thus ignoring the short to ground. The chip is shorted on Vdd.