TPS2544: How to test BC1.2 work with TPS2544?

Hello Randy,

Thank you for posting your question here on E2E. You can use an old phone or any other BC1.2 sink device. You will want to connect an oscilloscope on the following connections.

- VBUS

- DM_IN

- DP_IN

- I_OUT (current coming out of VBUS)

You will look at the signals shown on the D+ and D- line to verify that the mode the TPS2544 is in is correct. I'll give an example for if you are trying to test and verify for CDP mode.  Here's a CDP timing diagram example found within the BC1.2 specification. The portable device starts the conversation by sending a signal on the shared D+ line.  The source device detects this, and sends a response back on the D- line. The Portable device receives this response, and to verify that the D+ and D- lines are not shorted together (DCP mode), it sends another signal back through the D- line. The source device receives this signal through the D- line, but does not send back a response. Since the portable device never received a signal back on the D+ line, it knows that the D+ and D- lines are not shorted together, thus it is in CDP mode.

For DCP, the portable device will receive a signal both on D+ and D- since they are shorted together. For CDP, it will not receive a return signal at all since the D+ and D- lines are not shorted together and the source device will not send a response back.

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