MPQ4484 test sink simulation


my company is designing a high volume automated test system for a customer that is using an MPQ4484 charger on it’s design.
We build a PCB that can load the VBUS supplied and measure the current, and we have probes to measure the Dp Dn lines too.
The data lines are connected with a 150 Ohm resistor on the device.
We noticed that sometimes the MCP4484 is giving out 2.7 volts on Dp/n to gnd, sometimes 0.5v.
The measure is taken with no load on VBUS and no pullup/down resitor on Dp/Dn.

My guess is that we are confusing the autodecttion scheme described in the datasheet as below:

The MPQ4484 integrates a USB-dedicated
charging port auto-detect function. This function
recognizes most mainstream portable devices
and supports the following charging schemes:
–> USB battery charging specification BC1.2/
Chinese Telecommunications Industry
Standard YD/T 1591-2009
–> Apple divider mode
–> 1.2V/1.2V mode
–> USB Type-C 5V @ 3A DFP mode
The auto-detect function is a state machine that
supports all of the DCP charging schemes
above. Connect DP and DM with 150Ω resistor
for DCP mode.

So my questions are the following, is there a way to trick the autodetection to go always in the same direction (eg Apple divider mode)? How does this autodetecton work?



Hi Marco,

We’d prefer to move this off the forum and more towards our technical team MPS Now where we can give you better support. Can you please email MPS Now regarding your questions and all relevant information to

Brendan Schoemehl
Field Applications Engineer
Monolithic Power Systems | MPS Now