TMP1827EVM: changing the EVM to bus power

Lenio Cacula

Part Number: TMP1827EVM
Other Parts Discussed in Thread: TMP1827

When changing the EVM by breaking out the TMP1827 board and switching to bus powered configuration, the EVM is reading all 0xFF's. Is there a special configuration to be made so the GUI can switch from VDD to VPUR?

I am assuming the pullup resistor needs to be changed according to the equation 2 of the datasheet. If using 3.3V as Vdd, the resistor range should be between 750Ω and 2.2kΩ. We should then replace R9, currently at 390Ω.

Thank you!

8 months ago

+1 Ren Schackmann 8 months ago

TI__Mastermind 39845 points

Hi Lenio,

The resistor should be larger, as you suggested, based on the VOL spec. I'm not sure why that was missed in the EVM design. At any rate, this should not be the reason that bus power doesn't work for you. Have you connected your VDD to GND? The TMP1827 VDD pin must be grounded for bus powered operation.

thanks,

ren

0 Lenio Cacula 8 months ago in reply to Ren Schackmann

TI__Genius 16130 points

The issue was with the soldering of boards - it's resolved now. Thank you!

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TMP1827EVM: changing the EVM to bus power