LDO DC/DC Converter

[[email protected]]

Need a little help here. I am looking for a LDO DC/DC Converter. I
have 7.5V input, looking for 5V output. Total current output needs to
be upwards of 1A. Power consumption is critical and must be as low as
possible since the 7.5V is from batteries. For this reason I have had
a hard time finding an appropriate part. Any ideas?

Cheers,
Mike

 

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[Robert Latest]

Need a little help here. I am looking for a LDO DC/DC Converter. I
have 7.5V input, looking for 5V output. Total current output needs to
be upwards of 1A. Power consumption is critical and must be as low as
possible since the 7.5V is from batteries. For this reason I have had
a hard time finding an appropriate part.

If power consumption is critical, you need a step-down (buck) switching
regulator. Don't look for "low dropout" parts because that concept only
makes sense for linear regulators.

There are scores of ICs that can do what you want. Linear Technology's
is a website you might want to start at.

robert

 

[Winfield Hill]

If power consumption is critical, you need a step-down (buck) switching
regulator. Don't look for "low dropout" parts because that concept only
makes sense for linear regulators.

Right. Under "dropout" conditions the switch in an ideal buck
regulator simply stays on all the time. Assuming it's a MOSFET,
the value of Rds(on) for the gate-drive condition at the input
dropout voltage will determine the input-output voltage drop.
You can select a larger MOSFET to reduce the drop if you wish.

If the pass-switch is a BJT, its saturation voltage at the load
current will determine the dropout voltage. Some regulators use
up a small additional drop for a current-sensing function.

There are scores of ICs that can do what you want. Linear Technology's
is a website you might want to start at.

As well as all the other usual suspects.

 

[mpm]

Need a little help here. I am looking for a LDO DC/DC Converter.

Take a look at the National Semiconductor LM2575 (1-Amp)
or the LM2576 (3-Amp)

I've used the 2575. (9-pin TO-220 package)
It requires an inductor, a Shottkey diode, and input/output caps.
So you're looking at a 5-component solution if you go that route.

My guess is the 2576 requires a pass transistor, but I don't know that
for certain.

Good luck.
-mpm