CC2640 GPIO Pin leakage current in tri-state

Christoph Steurer

Other Parts Discussed in Thread: CC2640

Hello Community,

in the Technical Reference Manual of the CC26xx Family in chapter 11.6 it is mentioned that an tri-stated I/O Pin might have some leakage current if connected to a differential voltage potential.

Now my questions are the following:

1. How high is the leakage current if connected to a certain voltage level

2. For further calculation of the schematic around the CC2640, is it possible to assume an fixed inner resistor value to VDD or GND if the I/O Pin is in tri.state? If yes, what is the value?

3. Is there a more detailed schematic of the inner circuit of an I/O Pins available as the one stated in chapter 11.10.1 Physical Pin (found in Technical Reference Manual of the CC26xx)?

Thanks in advance.

over 9 years ago

0 Fredrik K over 9 years ago

TI__Guru** 106705 points

Hi Christoph,

You will only tri-state the pins if they are pulled firmly to either ground or VDD externally (when used as digital input). For analog, the pins can obviously be at any voltage potential without causing leakage.

Cheers,
Fredrik

0 Christoph Steurer over 9 years ago in reply to Fredrik K

Prodigy 25 points

Hello Fredrik,

thanks for your answer.
For my application I'd like to use the I/O Pin to pull down a resistor network against GND. To release the network I thought about switching the I/O Pin to tri-state and in the best case there is no leakage current. But mentioned above, the documentation tells something different.

To your answer: means "any voltage" also voltages above the supply voltage of the µC? Is there no internal diode connected between I/O Pin and VDD and GND?

Thanks.

Best regards
Christoph

0 Fredrik K over 9 years ago in reply to Christoph Steurer

TI__Guru** 106705 points

Hi Christoph,

VDD > any voltage > GND :-)

Cheers,
Fredrik

0 Charlie Sweet61 over 9 years ago in reply to Fredrik K

Prodigy 60 points

Hi Fredrik,

Please clarify how low is "no leakage current". Typically, analog inputs of analog components such as comparators or op amps have some maximum bias current. Can you provide some data on the maximum static input current of the CC2640 family analog, digital GPIO and reset inputs without internal termination resistors.

Cheers,

Charlie

0 svendbt over 9 years ago in reply to Charlie Sweet61

TI__Mastermind 29650 points

When all input buffers are disabled the entire device including pins draw around 90nA typically. (room temp).
All analog modules are disconnected from the pins when not used so they will not draw any current.
If the digital input is enabled the leakage current will depend on input voltage. Mid-rail you can typically see 2-400uA leakage current. This should however be avoided as a digital input should be either VDDS or GND.

Regards,
Svend

0 Charlie Sweet61 over 9 years ago in reply to svendbt

Prodigy 60 points

Hi Svend,

Thanks for your description.

My problem is slightly different so the 90nA typical leakage current is probably too low. I am using the inputs enabled with external pull-ups or pull-downs instead of higher current consumption internal pull-ups or pull-downs. What is the max leakage current of a digital input when held to digital low or digital high using external pull-ups or pull-downs at 25oC (room temperature)?

Regards,

Charlie

0 Christin Lee over 9 years ago in reply to Charlie Sweet61

TI__Guru 56045 points

You can find those numbers in our datasheet. Section 5.20 DC characteristics

0 Charlie Sweet61 over 9 years ago in reply to Christin Lee

Prodigy 60 points

Hi Christin,

Not on my version of Section 5.20 of http://www.ti.com/lit/ds/symlink/cc2640.pdf

0 Charlie Sweet61 over 9 years ago in reply to Charlie Sweet61

Prodigy 60 points

Hi Christin,

Datasheet ( Section 5.20 of www.ti.com/.../cc2640.pdf ) does not include leakage of dgital inputs with pullups and pulldowns DISABLED at valid high and low logic levels. Please provide this data (at least at room temperature). Prefer over 0 - 70oC temperature range, maximum instead of typical.

Sorry for any confusion as previous message at 12:45 PM today was unexpectedly truncated.

Regards,

Charlie

0 Christin Lee over 9 years ago in reply to Charlie Sweet61

TI__Guru 56045 points

We don't have those numbers, but when it's configured as input without internal pull-up/pull-down. It's basically the numbers as Svend pointed out, typically 90nA.

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CC2640 GPIO Pin leakage current in tri-state