TPS61040 capable of supplying 100mA?

Thank you Chris!

TPS61040 is out of the picture. I will look up the TPS61170, meanwhile, the TI site sugested TPS61093 and TPS61081. Due to the slow response (400ms) to the EN input, for the TPS61081, I am looking at the TPS61093.   I was trying to size the components from the TPS61093EVM, to fit my needs, but got into problem at the inductor. Do you have any hints?

Thenk you in advance (again...)!

Bogdan Orasanu

I'm not sure what you mean by 'the slow response (400 ms) to the EN input.'  The TPS61081 has an external soft start cap that can adjust the start-up time.

Both the 081 and 093 have input to output isolation.  This means that Vout can go to 0 when Vin is applied.  In a normal asynchronous boost, Vout is always a diode drop below Vin because the output cannot be disconnected from the input.

The TPS61170 is the simplest option of the 3.

There is a short inductor selection section on pages 11 and 12 of the datasheet with a table of recommended inductors.  What problem are you having?

Oh, sorry, my brains are out, again!

I was referring to the Toff from the datasheets (74ms vs. 1ms). I do not have the calculations handy, but it was something to do with the L value I calculated vs. the one from the "power stages of power converters" tool.

As for the input-output isolation, I like that. Maybe I should explain what I am trying to do:

The 12V output has a sequential constraint for on and off like this:

The Vcc is the 12V, and Vdd is 3.3V.

Best regards,

Bogdan Orasanu

Yep, your solution looks good.  Have you thought about using another TPS54x40 to generate the 12V straight from the 24V input?  It would be more efficient.

Do you need anything else on this design or have other designs that you are working on?

Ha, do you read minds!?

I was actually looking at TPS54286 (family) to generate both in paralel, but due to the timing constraints, I thought to go serial. Overkill, but...

Talking about different parts, I was looking for a TI substitute for the MAX 8211 that I use to detect the 24V going down. I could not find one. Did I miss it?

Best regards (and thanks!),

Bogdan Orasanu

Yes, we have the TPS3806 family.

Hmm, it looks quite good. Too bad you do not have any EVM for it.

BTW, is there a way to get the gerber files for the TPS61093EVM and TPS54140EVM?

Best regards,

Bogdan Orasanu

The gerber files are usually available on either the product page for the IC or product page for the EVM.  If they are not there, then start a new post for each IC and we can upload them for you.

What would you like to evaluate on an EVM?  Being a SOT-23 package, it should fit on any generic board with that footprint.  This SOT23 board for LDOs may be able to work for you: http://focus.ti.com/docs/toolsw/folders/print/dem-sot23ldo.html

Thank you Chris!

I'll do that.

Best regards,

Bogdan Orasanu