AWR1642: Questions on internal pull-up/down resistor

Chris Meng

Mastermind 35185 points

Part Number: AWR1642

Hi,

I have some questions about internal pull-up/down resistors. Would you pls kindly help?

1. What's the value of the internal pull-up/down resistors for GPIO pins?

2. If the internal pull-up/down is disabled by SW, what's the impedance of the input of GPIO?

3. Does the change of temperature affect the value of internal resistor?

over 5 years ago

0 Cesar over 5 years ago

TI__Guru*** 138329 points

Hi,

1. It is provided in the IBIS mode. Is your customer able to run the IBIS model?

2. This information should be provided in IBIS model

3. Very little change

thank you
Cesar

0 Chris Meng over 5 years ago in reply to Cesar

TI__Mastermind 35185 points

Cesar,

Customer has no SW run IBIS model on-hand now. I don't have either.

Would you pls help to run it and share some snapshots?

0 Chris Meng over 5 years ago in reply to Chris Meng

TI__Mastermind 35185 points

Cesar,

Would you pls help again?

0 Chris Meng over 5 years ago in reply to Chris Meng

TI__Mastermind 35185 points

Cesar,

Customer found a tool to run AWR1642 IBIS model, but can't find value of input impedance & value of internal pull-up/down resistor for GPIO pins with IBIS model.

Would you pls help to double check?

0 Radio-Joe over 5 years ago in reply to Chris Meng

TI__Mastermind 37500 points

Hello Chris,
The IBIS model has a pinname to model selection
Using GPIO0 as an example
GPIO0 refers to Selector 3

Depending on the Pin Mux, this refers to the actual model
example Model_10

We are trying to ask the designers for a value or range. Since GPIO can be write or read, the Model_10 has to be configured, so there is not
a direct impedance, pullup, pulldown answer.

We will update when we get an engineering answer.
Regards
Joe Quintal

0 Chris Meng over 5 years ago in reply to Radio-Joe

TI__Mastermind 35185 points

Joe,

Thanks. Waiting for your update for the detail info.

0 Radio-Joe over 5 years ago

TI__Mastermind 37500 points

Hello Chris,

I have asked the design for the input pullup, input pulldown, and drive strength,

They have indicated this is in the IBIS model provided.

I will have to download an IBIS tool. The designers indicate that the IBIS model

has the information for customers. The difference is that we need to select which

Pin mux of the specific pin to evaluate the model.

I will try to write up an example. You can also list specific pins you need the values for.

Regards,

JoeQuintal

0 Chris Meng over 5 years ago in reply to Radio-Joe

TI__Mastermind 35185 points

Joe,

Customer wants to know the internal pull up/down resistor value of pin R4 and P5. Would you pls help?

0 Radio-Joe over 5 years ago in reply to Chris Meng

TI__Mastermind 37500 points

Hello Chris,
From one evaluation the pullup and pulldown resistors are in the range of 16 - 24K.
The input impedance is an estimate, still need confirmation 100K.
The VIH, VIL are shown in the datasheet. Note for NRESET the value is different from GPIO.
The VOH, VOL are shown in the datasheet.
Regards,
Joe Quintal

0 Chris Meng over 5 years ago in reply to Radio-Joe

TI__Mastermind 35185 points

Joe,

Why the value of internal pullup/down resistor is a range, instead of fix value for pin R4 or P5?

0 Radio-Joe over 5 years ago in reply to Chris Meng

TI__Mastermind 37500 points

Hello Chris,
The design specification has a wide range. Since its inside an IO cell definition, that is predefined, the current range has a large tolerance.
If your customer puts the pins in question in an IBIS simulation, with the proper pin mux selection of a model, that is the information we have.
If we have a nominal 20K pullup or pulldown, we expect the input impedance to be ~100K ohms.

In the DMM Bus usage, the bus is based on an integrated data stream for Radar Rx, number of channels, real / complex data format, DFE output rate. The 16bit DMM bus, is interleaved in time, so that a 6.25Msps DFE output rate, with 4 Rx, and complex data ->
2 16bit transfers per IQ * 4 Rx * 6.25Msps = 50Mhz clock rate.

Regards,
Joe Quintal

0 Radio-Joe over 5 years ago in reply to Chris Meng

TI__Mastermind 37500 points

Hello Chris,
This is the information I got from Chethan. There is a range of pullup and pulldown current that is allowed. I took the current range, and VIOIN voltage and calculated the resistance range.
Regards,
Joe

0 Chris Meng over 5 years ago in reply to Radio-Joe

TI__Mastermind 35185 points

Joe,

Which tool are you using to run IBIS model of xWR1642?

I tried Altium designer, but got below output. I can’t see the pullup/down info for each pin clearly. What did I miss? I added ibis model for xWR1642 component.

0 Radio-Joe over 5 years ago in reply to Chris Meng

TI__Mastermind 37500 points

Hello Chris,

We do not have an example IBIS project to test the IBIS model. I went through the list of models presented for Pin Muxing, and asked the design team for more comments.

Regards,

Joe Quintal

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AWR1642: Questions on internal pull-up/down resistor