bq40z50R1通讯问题

目前此芯片已做成PCB板，并已经做成3S2P的电池包，在我进行测试过程中发现，连接EV2300以后，可以正常和上位机软件通讯，但是连接了大概2个小时左右，通讯突然断开了，怎么也连接不上。这个芯片使用了system present pin，目前是悬空，2个小时过程中，我就用导线把此pin和P-短接过一次。

请帮忙分析可能的原因！

Time Based Shutdown The device can be configured to shut down after staying in SLEEP mode without communication for a preset time interval specified in the Auto Ship Time. Setting the PowerConfig[AUTO_SHIP_EN] = 1 enables this feature. Any communication to the device will restart the timer. When the timer reaches the Auto Ship Time, the time based shutdown effectively triggers the MAC shutdown command to start the shutdown sequence. The device returns to NORMAL mode when voltage at PACK pin > VSTARTUP.

ths，done！