Power Distribution

TPS22942 question

Nikolaos Agianniotis — Wed, 11 Nov 2009 10:08:04 GMT

I would like to clarify, if the ON enable pin of the TPS22942 part is active low or active high. In fact, at the table (feature list) at the beginning of the datasheet it is written that this is true. However, at the application information (page 13 of the datasheet) it is written that the ON pin is active high.

In case that TPS22942 is not active low enabled, is there any other 1.8V compatible with active low enable pin power switch?

Thank you!

TPS2228 Questions

Mike Bulat — Thu, 22 Oct 2009 19:40:10 GMT

Hello,

We used in the past TPS2202I and later we switch to TPS2228 -TSOP30 because we need support for low voltages.

I do have some questions RE TPS2228 we presently use

· Logic power supply pin

The old TPS2202 had a useful feature for us: it had a separate power supply for the logic core.

In our application case we need to vary the VIN voltage levels. With the new TPS2228 we have to limit the 3.3VIN level to min 3.0V (this supplying the logic power too). This is a big limitation for us and I guess nothing can be done.

Question: The chip doesn’t have somehow any other separate Logic power supply pin, maybe under NC?

· UVLO (under voltage protection) :

With the older TPS2202 we could go over the spec range for VIN (for example with the 12VIN as low as approximate 2.5V).

As I mentioned above in our case we need to vary the VIN over a wider range (ideal is as low 1.1V where I think the switch will be still working), but in TPS228 the UVLO protection kicks-in and disable the switch (true according to spec)

Questions: Is anyway to disable the UVLO feature? Do you plan any new chip with the option to disable the UVLO? Or any chip with a wider VIN ranges?

Current limiting a power supply

MikeW — Wed, 16 Sep 2009 20:46:49 GMT

Hello,

I'm trying to find a solution that lets me regulate the output of a 5V supply to 500mA. The supply is attached to a circuit that could easily pull twice that current if I let it but I don't want to let it as that load is hard on my design and puts the design at or beyond the specified safe operating area (heavy demand on the battery especially).

I don't want to use a power switch that shuts off the output and especially not one that requires an EN pin to be reset. It would be tripping constantly and the output would be useless. What I need is an IC (or maybe new switching regulator all together) that I can set to provide 500mA like the way a battery charger chip does it (fixed current). The input to my power supply is a small 3.7V LiPo cell rated at 1350mAh and a 1A load really pulls the voltage/capacity down quickly. Does TI make a part or part combo that can do something like this?

Thank you.

capasitor power supply

kanaga raj — Fri, 14 Aug 2009 10:14:36 GMT

I'm using capacitor power supply to Msp430.In this power supply using three phase,two and single phase supply.In this three and two phase are properly working but in single phase was not properly working.

Output:

5v/30mA required

In this i'm now using 100ohm resistance and .47uF capacitor.

Please give design procedure

I already refereed the document(SLAA024) for design process, from this i cant get the proper solution.

TPS2054B questions

Charles MacDonald — Sun, 28 Jun 2009 17:13:27 GMT

When an output of the TPS2054B is disabled (ENx=L) what are the limitations on how that output pin may be driven by other devices? I want to provide power to a circuit in two ways: through the TPS2054B when a USB connection is present, otherwise, through a 7805 voltage regulator driving the same +5V rail when external DC power is available.

Is it safe to tie multiple outputs together, say two, in a situation where either one or both of them will be enabled?

The TPS2064 datasheet specifically lists reverse current blocking as a feature in the summary. This is not listed for the TPS2054B. Does it not have this feature?

Are there any brief descriptions of what is different between the TPS2054, TPS2054A, and TPS2054B parts?

TPS2359 i2c problem. Please help.

sviss — Fri, 26 Jun 2009 16:48:35 GMT

Hello,

I designed uTCA shelf board with two TPS2359 power distribution controllers on it.

Looks strange, but I fail to communicate with them via i2c: no acnowledge from any of the two TPS2359 connected.

I've tried several hardwired addresses, than wrote an i2c bus scanner - nothing helped.

I use MSP430 i2c hardware programmed to 100kHz SCL clock rate. It works OK with other devices.

What could be a reason for TPS2359 i2c to not to reply/acknowledge?

I looked through all the pins: nothing suspicious.

Could a thermopad be a reason? There is no wording in the datasheet what to do with it. I left it isolated.

Unfortunately it is much more difficult for me to try connect it now (the pad is under soldered QFN36) than to ask for your help here.

Any comments / ideas?

Thank you.

Trouble with TPS2226A

Jens Guessregen — Thu, 25 Jun 2009 13:33:25 GMT

Hello,

we made a design with 1520 Dual PCMCIA Controller from TI. We are using TPS2226ADB for power switching. The design is made as PCI add-in card, so we are using only PCI parallel interrupts.

At least, this is not a very special or even complex design. That I was thinking before we started production of initial batch. Now, after a few days testing, we have failure rate of 25%. We found out, that the 2226ADB is burning away. This chip is showing the same burning areas more or less the same on all burned chips. This areas are corrosponding to both 12V input pins. BUT, there are no cards inserted into the cardbus slots. So no current should be used by this input pins.

We double checked schematics, every thing is ok, regarding datasheets and also reference design. So we went deeper and tried to check for the serial protocol between 1520 and TPS2226A, but we also found a note in the datasheet, that definition of D0 to D10 can be seen at control logic table, but this table is not part of the datasheet ...

Maye somebody has seen that before?

Thanks Jens

undervoltage Lockout vor Car 12V

Norman Joerns — Thu, 30 Apr 2009 09:01:25 GMT

Hello,

is there a solution vom TI to cut the load from the 12V car battery when the voltage drops below a certain level? I've seen this future e.g. with camping cooling boxes.

regards

Norman Jörns

TPS23363 power

Bob Kando — Mon, 19 Jan 2009 14:43:43 GMT

Can the TPS2363 can run at 40W vs the 25W it is rated at. Can our part run at 40W? If not is there another part or a way to configure the surrounding circuitry to meet the 40W need?