BQ2947: delay time when CD capacitor is opened

Kotaro Yamashita

Intellectual 2150 points

Part Number: BQ2947

Hello Team,

I would like to understand that the delay time during OVP condition when CD cap is opened. Is that same of tCD_GND?

Regards,

Kotaro Yamashita

over 4 years ago

0 WM5295 over 4 years ago

TI__Guru 54715 points

Hi Kotaro,

When the CD capacitor is opened, the pin and trace will still have some small capacitance. See equation 1 in the data sheet for calculation in http://www.ti.com/document-viewer/BQ2947/datasheet/external-delay-capacitor-cd-slusb153980#SLUSB153980

If the residual capacitance were 100 pF, the delay expected would be 1 to 2 ms. Note that this is faster than the customer test mode which is a recognized by the shorted condition. Internal delays may limit the time of very small capacitances.

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BQ2947: delay time when CD capacitor is opened