TPS22970: ON Pin

HI Timothy,

Is the TPS22963/4 able to terminate ON to VIN?

How does one determine the necessary RC delay to terminate ON pin to VIN?

How does one determine the appropriate RC delay needed to connect ON to VIN on load switches other than TPS22992?

In general, we do not recommend connecting the ON to VIN pins as we do not have reliable guidance on the RC delay needed to prevent the abnormal slew rate (it is not part of the test flow of the device). If the application is to connect ON to VIN, we recommend using the 99x family of devices. 

There was mention of RC delay needed.  Where can I find more information?

How about TPS22964? The data sheet has an example layout for power sequencing without a GPIO input.  The part's ON is directly connected to VIN without RC delay.  See page 17 in TPS22963,64 Datasheet by Rochester Electronics, LLC | Digi-Key Electronics (digikey.com)

After Kalin's reply I checked with our design team and the recommendation was not to configure the device with the use case. As we are not able to quantify the exact RC delay needed to avoid the slew rate behavior, we inherently do not recommend this configuration for the device. 

The data sheet has an example layout for power sequencing without a GPIO input.  The part's ON is directly connected to VIN without RC delay.  See page 17 in TPS22963,64 Datasheet by Rochester Electronics, LLC | Digi-Key Electronics (digikey.com).  So is the datasheet wrong?

Andrew,

I apologize and see what you are saying now. For the TPS22964/65 you are able to use it in a sequencing setup like you are seeing in Figure 40. In this case the sequence of devices will turn on with the expected sequence. 

For the RC delay, you just have to make it so that your VIN level is at 100% before the ON voltage reaches the VIH, ON logic level in the datasheet. This will ensure that the VIN rail is at a known level before enabling the device. 

Are you looking for a WCSP package option where you are able to tie IN and ON together? Could you elaborate a bit more on the specific application and I can find a device/configuration that matches the use case?

Timothy,

The sequencing is not my main question.  In Figure 40 (module 1) of the data sheet the first TPS22964 has the ON pin tied directly to VIN without an RC delay.  Is this figure/method valid?  Or do I need to add an RC delay to the module 1 load switch?

Andrew,

I am conferring with the design team about the exact conditions here and the behavior we would expect to see when tying the two pins together. Is it OK to reach out via the email on your TI account to follow-up here? I will circle back here once resolved for completeness.