IWR6843: Pin characteristics for NRESET(ball#R3)

rperezti

Part Number: IWR6843
Other Parts Discussed in Thread: MMWAVEICBOOST

I am looking for information about the NRESET (ball#R3) input pin characteristics such as input current and presence of an internal pull-up or pull-down resistor.

I am referencing IWR6843 datasheet (SWRS219B, Sept 2019 revision) and I can't find this information. I don't see a spec for input current on any digital I/Os including NRESET. Also, the Reset pin (NRESET) is not included in Table 4-1.

From empirical measurements we believe the NRESET input may have a 30K ohm pull-down resistance to ground as we are measuring a 83uA current into the device when we pull the pin high. Is this expected?

over 5 years ago

0 Charles Oladimeji over 5 years ago

TI__Mastermind 33805 points

Hi,

I will get back to you with some details.

BR,

Charles O

0 Charles Oladimeji over 5 years ago in reply to Charles Oladimeji

TI__Mastermind 33805 points

Hi,

I am still working on getting this information to you.

Thanks,

Charles O

0 Charles Oladimeji over 5 years ago in reply to Charles Oladimeji

TI__Mastermind 33805 points

Hi,

The nRESET pin has a 300k pull down resistor

BR,

Charles O

0 rperezti over 5 years ago in reply to Charles Oladimeji

TI__Genius 12670 points

Charles,

Thank you very much for chasing this down for us. Hopefully this information will make it into the device datasheet in a future revision.

My original estimate of 30Kohms was based on an assumption of an external pull-up value of 10Kohms, but now I confirmed that the external pull-up value is 100Kohms so the current into the pin is 8.3uA, not 83uA.

Note that the R/C values on the MMWAVEICBOOST carrier board of R120=100Kohm and C24=1uF cause a very slow rise time on IWR6843 NRESET. With this combination of component values it is not possible to reliably reset the IWR6843 through the booster pack connector. For example, when mating the carrier board with the MMWAVEPOEEVM, it is not possible to reset the IWR6843 reliably using the MSP432E GPIO pin that connects to NRESET through the booster pack connectors. In order to make this work reliably, we had to reduce the values of R120 and C24 on the MMWAVEICBOOST board.

Ruben

0 Charles Oladimeji over 5 years ago in reply to rperezti

TI__Mastermind 33805 points

Hi Ruben,

Thanks for the feedback.

BR,

Charles O

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IWR6843: Pin characteristics for NRESET(ball#R3)