• TI Thinks Resolved

TPD4S014: TPD4S014 ACK behavior on VBUS removal

Part Number: TPD4S014


I am currently using the TPD4S014 in multiple designs and on odd behavior has been noticed on all 3 designs.  When the VBUS is removed (USB cable is detached) the ACK signal is de-asserted (as expected) after it crosses below UVLO-.  Strangely, after a long period of time (roughly 600mS) it is re-asserted for about 750mS before de-asserting again and staying that way.  The timing is consistent on each design, but is marginally different between the designs.  I've arrached a scope capture of VBUS (green) and ACK (yellow).  All devices are powered via a single Li-Ion battery.  The ACK signal is connected directly to an MSP430 input pin and pulled up to VCC (3.3v) with a 10K resistor.

Is this typical behavior or to be expected?  If not any ideas on what could be the source of this bahavior?