TPS25750: TPS25750 - setting current limiter and Rp value in configuration

Hello again,

We have tried the suggested fix, but on TPS25750 this has no effect.

We have tried with several different values including 0 for maximum current in the PDO, but nothing changes.

The output still can pull 3A at any time.

I have attached the configuration in use.

Any hint to what is wrong would be helpful.

Thanks,

/Peter

{
"questionnaire": {
"device": "TPS25750",
"answers": [
null,
8,
0,
0,
0,
1,
2,
0,
0,
0,
null,
0,
0,
0,
0
],
"vendorId": "0B0E",
"productId": "FAB3",
"version": "1.0.0.2"
},
"configuration": {
"data": {
"selected_ace": [
{
"register": 6,
"data": [
0,
0,
0,
0,
0,
0,
0,
0
]
},
{
"register": 22,
"data": [
10,
48,
48,
77,
0,
0,
0,
0,
0,
0,
3
]
},
{
"register": 50,
"data": [
1,
168,
42,
100,
144,
1,
38,
44,
209,
2,
0,
44,
177,
4,
0,
244,
65,
6,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
]
},
{
"register": 51,
"data": [
0,
44,
145,
1,
16,
44,
209,
2,
0,
44,
177,
4,
0,
244,
65,
6,
0,
69,
65,
6,
0,
0,
0,
0,
0,
0,
0,
0,
0
]
},
{
"register": 92,
"data": [
48,
0,
0,
0,
0,
0,
0,
0,
0,
16,
0,
0,
0,
0,
0,
0,
48,
0,
0,
0,
0,
0,
0,
0,
0,
12,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0,
0
]
},
{
"register": 117,
"data": [
0,
0,
0,
0
]
}
]
}
}
}

Hi Peter, 

Could you please share the configuration in a json file format (try dragging the file into the E2E)?

Peter Dons Tychsen said:

The output still can pull 3A at any time.

Do you have scope captures of this behavior?

Best Regards, 

Aya Khedr 

OK here it is (its the same as the one above)

config_bad_3a.zip

Hi Peter, 

Thank you for providing. I will replicate on my end and share results by end of day Thursday. 

Best Regards, 

Aya Khedr

OK great. Looking forward to your input. We are at a critical point where we we need to make this work or switch chip.

Hi Peter, 

Could you also provide your test setup so I can replicate on my end? Are you using the TPS25750 EVM? What sinking device are you using ?

I will have some initial results by tomorrow.

Best Regards, 

Aya Khedr 

Hi Peter, 

I replicated on my end using the following setup:

• Flashed TPS25750 EVM with provided json config_bad_3a.zip using GUI https://dev.ti.com/gallery/view/USBPD/USBCPD_Application_Customization_Tool/ver/0.6.0/
• Negotiated 5V contract using the USB-C-PD-DUO-EVM as the sinking device
• Varied the E-load from 0.5A to1.6A (the max that the device could pull was ~1.6A)
• See PD logs current/voltage monitor for the exact current it tripped at (notice how the VBUS voltage drops from 5V to 0V when the current load surpasses ~1.6A

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/TPS25750_5F00_Source_5F00_Duo_5F00_sink_5F00_ELoad_5F00_1A_5F00_OCP.tdc

Are you using the TPS25750 EVM to test? Do you have a scope capture similar to the one above showing voltage/current when varying the load?

Please let me know if you have additional questions/concerns. 

Best Regards, 

Aya Khedr 

OK thanks I will repeat here.

Hi again. Please try without negotiation.

In one of the failing cases the SOURCE device is just connected to a load, without any negotiation on the CC lines.

In this case the limiter does not work as expected.

Please try this.

Thanks,

/Peter

In other words, connect the load directly to the source, not via a real sink device.

This does not work.

Hi Peter, 

Are you connecting the load directly on VBUS? Could you send a diagram of your setup?

Best Regards, 

Aya Khedr

Yes, load is directly connected to VBUS. See attached schematic