Is this possible?

Is this is possible?

I just had a client request a +1V supply (a switcher) that SINKS


I only have +5V available :-( ...Jim Thompson

| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Jim Thompson
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You didn't specify what the 1 volt is, input? output? etc.. but here is something

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that will output starting at .8 volts but needs supply voltage of

2.7.. 5.5v
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Modern DRAMs often need termination. Since they have a lot of signals, it's less power overall if you terminate to the target voltage and that requires a regulator that can sink as well as source.

There should be lots of data sheets out there.

I assume you don't need to make a switcher that can pump the power back up to 5V rather than just turn it into heat.

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Reply to
Hal Murray

Simple. Any 1V supply chip, and just load it with 5 ohm, so it can sink 200ma and source (Ispecified-200ma).

Reply to
Sjouke Burry

Wierd. A CC 200mA load across the supply? Maybe switched in or out depending on whether the +1 supply is on or off?

Please post how you solve it, if the NDA allows. Inquiring minds want to know! :-)


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That doesn't say whether this switcher will work in two quadrants (current source plus current sink).

"Source" is typical verbage for a power supply spec. So Jim's customer either used bad terminology in the spec or they really want something to sink current. I understand the confusion. I'd look over the spec for an additional 'source' specification. If none is found, I'd go back to the customer for clarification.

Paul Hovnanian
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Paul Hovnanian P.E.


Linear Tech has a number of DDR2/3 switchers for termination supplies that can sink and source...

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-- Marc

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Marc Guardiani

"Jim Thompson" wrote in message news:

As somebody else mentioned, these types of supplies that guarantee that they can sink (as well as source) are used for mid-supply memory terminations. They're referred to as "VTT" or "termination" supplies.

Here's a table of LT termination switchers. They are overkill.

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If you can convince the customer to use a linear (it is fairly low current) then the TI TPS51100 will work. You'll just need to fake a 2V supply because its output is half of the reference supply.


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