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  • TI Thinks Resolved

TPD8S300: TPD8S300 problem when unpowered

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Replies: 1

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Part Number: TPD8S300

Hello Sirs,

We use TPD8S300 for type-C port protection in Motherboard application.

When S0 mode, everything is OK !  VBUS could output 20V for 20V device ( LCD monitor ) CC1 and C_CC1 pin is 1.6V.

When S5 mode , PD controller still alive but TPD8S300 unpowered . We found CC1 voltage will drop from 1.6V to 1.33V  and C_CC1 pin is 0.84V .

If this moment we remove device (LCD monitor ) , CC1 is 2.1V , C_CC1 is 1.6V . Problem is Vbus still keep 20V and if we plug 5V devices , it was damaged !!

Base on PD ic's comment . PD IC could not detect device removed so that still keep previous status (20V sourceing) .

Since device (Rd resistor) removed , PD IC's Rp pull up to PD's Vdd 3~4V is normal . And CC pin could return to toggle .

Would you pls help to comment this behavior ?

TPD8S300 unpowered , C_CC pin still have voltage around 500mV drop from CC pin <= Is this a leakage ?

Should I disconnect Rpd_g1 Rpd_g2 with CC1/CC2 and change to GND ?

Many thanks !

BTW. We use male type of type-C connector .

  • You are not supposed to remove the Vpwr. If you remove Vpwr the device goes in Dead battery mode. You can see section 8.3.4 of datasheet for dead battery operation.  http://www.ti.com/lit/ds/symlink/tpd8s300.pdf 

    During normal operation the device always requires Vpwr and typically if PD controller has power this device should also be powered.

    Removing the Rpd_gx will only help in dead battery mode, to let the source (charger) provide VBUS immediately on connection.

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