Team,
we have a problem with enabling BC1.2 charging (CDP) with TPS254900-Q1 on our USB2.0 port.
The chip itself seems to be working fine. All the diagnostic pins are OK, but the phones simply won’t charge above 500mA as if they only recognize the SDP port. I took a look at the D+, D- to confirm the BC1.2 handshake protocol and it seems to be preset as well (few example oscilograms in below zip, yellow is D+ and green D- line). We have tested with several modern smartphones (iPhone, LG, Huawei, Samsung) but the result is always the same. The handshake is present, but the 1.5A CDP charging current is not.
The USB 2.0 port is connected to the processor, but this should not influence BC1.2 charging.
We are also using an automotive connector with a custom cable for our USB 2.0 port, but are skeptical that would cause an issue.
Huawei P10:
Battery SOC: 21%
IBUS: 484 mA
IMON @ 10k: 507 mV
LG K4:
Battery SOC: 92%
IBUS: 480 mA
IMON @ 10k: 503 mV
The results are that the current remains a bit below 500mA directly measured like in a SDP. IMON pin almost perfectly measures current as the theoretical typical value of voltage on IMON at 10k is less than 5mV from the actual measured values.
Can you advise what can be done here to solve this?
Thank you.
