TPS63802: EN pin connection to GPIO line

I have attached information about the GPIO mode of CC2642R.

Hi Pragash:

If the EN pin is open, it's hard to ensure the status of device. And it may be influenced by noise, and bring misbehavior.

 How about adding a pull up resistance?

are you saying that MCU GPIO is not suitable to be connected with EN pin of this regulator directly?

if we connect EN pin to a pullup, the regulator will be always ON and that's not intended. we want to be able to switch off the regulator using GPIO so we can save power. 

Hi Pragash:

I don't recommend connect it to a open drain.

For my understand, with a pull up resistance, GPIO->0 will turn off the TPS63802. While GPIO->1 will leave it open drain, and pull up by the resistance. 

I can agree when GPIO = 0, the current might flow into GPIO instead of EN and EN pin will be a shunt to Ground. When the GPIO = 1, the voltage of GPIO will be the same as the voltage of the pullup. GPIO = V1 and Pullup = V1. because the connection is parallel, EN pin also will see the same voltage, which is V1. the current will be the sum of current from MCU GPIO (Imcu) and Pullup current (Ipull). Ien = Ipull + Imcu. Why EN is open drain in this situation?

How about pulling EN down with resistor and then connect it to MCU GPIO?

Hi Pragash:

Let's take one step back. What's the status of the GPIO, when it's 0, or 1?

If it doesn't have internal pull up, how could it deliver a high level signal?

we are using CC2642R. we supply MCU with 3.3V. when GPIO = 1, it will be 3.3V

when GPIO = 0, it might be from 0.21 (VOL) to 0V. 

your comment: If it doesn't have an internal pull-up, how could it deliver a high-level signal? 

my answer: a good question but I think u don't understand what I'm talking about. I'm talking about when the time equals to 0s. when you power up / turn ON the device, what is the initial or default state of the GPIO? is it "pullup"? i don't think so!

hi Minqiu, 

I'm not able to figure out the initial state at T=0 for CC2642R. I have tried reading the technical reference manual fully but I'm not able to find maybe because I'm not a programmer but hardware engineer.

could you help me to find out the default or the initial start of GPIO lines? is it possible to change the default or initial values of GPIO lines?

Hi Pragash:

Sorry that I'm not familiar with CC3642R and I afraid I can't give you correct answer about that.

May you make a new post, so that my colleague from related product line can help you and make it clear.

correction in above question.

The GPIO pin of the CC2642R can't be open drain, which can be dangerous for EN pin.

i think high-Z at CC2642R is open for EN pin! how is it even a solution? 

Thanks for your confirm, TER