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TPS25762Q1EVM: USB FW Update

Matt S
Prodigy 30 points

Part Number: TPS25762Q1EVM

Tool/software:

TVSP pin connects to gnd through 6.65k resistor for TVSP index 8 to update FW from USB. Why does the gate of Q3 tie to VCC3V3 instead of LDO_5V like the other options (index 1-7)? Is the timing requirement of TVSP pin for USB update (index 8) different from the other boot options (index 1-7) ?

In the datasheet it shows USB update being triggered with a transistor which has a gate tied to LDO_5V, but it also mentions a boot cycle is required.

The datasheet also has a note which says 'required for index 1-7' on the previous diagram. This seems to imply there is something different about index 8.

  • 0
    TI__Mastermind 46441 points

    Hello Matt,

    The design of using the VCC3V3 for TVSP8 on this EVM is specifically intended for the TPS25772Q1EVM-CD-150. 

    The TPS25762Q1EVM, TPS25772Q1EVM-CO-149, and TPS25772Q1EVM-CD-150 are 3 variants of the same EVM design. The BOM are different to evaluate:

    1. TPS25762Q1EVM: Single port charging with the TPS25762-Q1
    2. TPS25772Q1EVM-CO-149: Dual port charging with TPS25772-Q1
    3. TPS25772Q1EVM-CD-150: Dual port charging + USB 2.0 data with TPS25772-Q1  

    Section 6.6 in the EVM User's Guide covers how on the TPS25772Q1EVM-CD-150, R141 is DNP and R142 is populated to enable the TS3USB221A-Q1 USB MUX (U12) which is needed to route the USB 2.0 data path from the Type-C receptacle to the Micro-B receptacle. Q3 is tied specifically to the VCC3V3 voltage rail as the USB_SEL signal driving the gate is also connected to the Select pin of the USB MUX (U12).

    In a normal application, it does not matter if 3V3 or 5V is driving the BJT or FET. 

    As for the boot cycle, a POR is required anytime you change the R_TVSP value to switch the device's Boot Mode.

    BR,

    Seong

  • 0
    Prodigy 30 points

    TVSP index 8 is required regardless of whether FW is updated by USB or I2C-> EPROM correct ?

  • 0 in reply to Matt S
    TI__Mastermind 46441 points

    Hello Matt,

    No, a 6.65k resistor option is not needed if USB Endpoint FW Update won't be used.

    If TVSP Index 0 is the only Boot Mode needed, R_TVSP can be left Open.

    BR,

    Seong