CC2541 GPIO drive strength / VOH

The output drive strength is 4 mA on all outputs, except for the two high-drive outputs, P1.0 and P1.1, which each have 20-mA output drive strength. If you need higher driving power, you should use P1.0 and P1.1.

Hi YiKai Chen

Thanks for your reply.

I am already using the two 20mA pins to drive LEDs.

My 1K pulldown only sources 3.3mA from the pin, I shouldnt need any more current.

Thanks

Jamie

Hello

Can anybody offer any suggestions for this problem?

Thanks

jamie

Hi,

There is nothing wrong with your HW, it's expected to have some voltage drop when devices is sourcing current. In the datasheet, we guarantee that when device outputs 4mA at 3V, the VOH does not go lower than 2.5V.

Is that a problem for you when device output 3V instead of 3.3V?

Hi Christin

Thanks so much for your reply - Ive been pulling my hair out with this one...

Ok a lower VOH isnt nessesarily an issue for me - I didnt know the voltage drop was expected behaviour I thought the device was being stressed in some way resulting in the voltage drop.

The remaining question is how much voltage drop can I tolerate.

(BLE113 VCC = 3V3)
The external device the BLE113 pin is driving has a VIHmin of 2.64V
The BLE113 VOL I am seeing is 2.94V
So this looks acceptable to me.

The question is...
I have measured BLE113 VOH of 2.94V (with 1K pulldown)
Can I expect to measure a VOH of 2.94V when I manufacture 50,000 units?
As there is nothing in datasheet for me to work with, how much can I expect the 2.94V to vary across thousands of BLE113?
Or is it safe to assume the 2.94V should remain constant?

Thanks for your help Christin

Best Regards
Jamie

Hi,
The voltage level when sourcing 3.3mA will vary from device to device. The only data point we have and can guarantee is that when device is power at 3V, the minimum of VOH while sourcing 4mA will be higher than 2.5V

Hi Christin

Do you have any information on how much the voltage level varies from device to device?

I know that Analog Devices always have much more test information available by request for each device than can be squeezed into the datasheet.
They just pick the most important information for the datasheet.

I wonder if TI do a similar thing?
Is there a way to escalate this and find out if there is more information available than is provided in the standard datasheet/user guide?

Thanks for your help

Best Regards
Jamie

Hello

Can any TI Employee comment on my last question?

Thanks

Jamie

Hi,

As stated, we can only guarantee the minimum voltage level when sourcing 4mA from the devices. We don't have any data point of VOH when sourcing 3.3mA unfortunately.

Hi

I was still looking for an answer on the last question I asked.

I appreciate you have advised you only have one specific datapoint regarding VOH level in the user guide.

I know that semiconductor manufacturers conduct many more tests and aquire much more data than can be included in the device datasheet / user guides.

I have been told in the past by other manufacturers that they are happy to provide this extra information on request.

So I was just asking if we could escalate this issueand find out if there is any unpublished information which could be provided?

Thanks for your help

Hi Fredrik

Thankyou, that is exactly the type of info I was looking for.

This has given us enough confidence to go ahead with our current PCB revision. You have saved me from weeks of work.

Thankyou.

Jamie