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TWL6032: Voltage leakage 2.5V at Vsys

Logan Lin
Intellectual 340 points
Part Number: TWL6032
Other Parts Discussed in Thread: TWL6030

HI Sirs:

Our cutomer found the voltage leakage 2.5V at Vsys through the USB_OTG_VBUS 5V of PMIC. If we remove this connection, there will be no voltage leakage, but the USB fastboot can not work.

If any posible of the voltage leakage at VSYS through the VBUS?

  • 0
    TI__Genius 17380 points
    Hi Logan,

    TWL6032 has power path features that supplies VSYS from either VBUS, VBAT, or VAC (with external IC). What other power sources are available? When VBUS is applied and VBAT is not available, VSYS is supplied by VBUS. I am not sure why it is only 2.5V, rather than 3.6 V / 3.8 V (see figure 4-12 in the datasheet). Are they using the TWL6032A2B7 OTP? (Note there appears to be a typo in the image above).
  • 0 in reply to Kevin LaRosa
    Intellectual 340 points

    HI Kevin:

    Let me clarify some question, from the schematic that I post above, they don't using VAC port and battery, but using external IC to generate 5V and connect to SMPSx_IN, VSYS_BB(I think the recommended voltage is 3.8V)

    From my undertsand, SMPSx_IN is generate from VAC port (maybe it has internal converter to transfer 5V to 3.6V/3.8V), and if they want to using USB for system sypply, it should be external components through CHRG_SW to transfer VBUS to 3.6/3.8V for VSYS.

    any mistake please let me know, thanks a lot.

     

  • 0 in reply to Logan Lin
    TI__Genius 17380 points

    Hi Logan,

    I think your understanding is correct. TWL6032 only supports 1 5V input by default, a second 5V VAC requires external chip. See Figure 4-23 in the datasheet. Alternatively, the second 5V can be bucked down and treated as VBAT, like they do in Pandaboard design with TWL6030: pandaboard.org/.../panda-ea1-schematic.pdf

    That said, if I connect 5V to VSYS on the EVM, VBUS sits at 0.15 V, not 2.5 V so may be related to customer board.

    For experimentation, TWL6032 EVM may help to compare with their board (www.ti.com/.../twl6032evm).