Low power linear voltage regulator

[Fabioedl]

Hi all,

I am looking from a very low power voltage regulator. The maximum input voltage is 13.2V and the supply current is about 250mA. I found a voltage regulator from Microchip (TC55) that is really nice because its quiescent current is only 1 uA, but the maximum input voltage is too low (about 10V).
Does anyone know a voltage regulator that meets this requirement? I was thinking about have a zener diode in series with the input line, but I don't know if the zener will work at that current level.

Thanks,

Fabioedl

 

[melone]

What are your output requirements, current, voltage, ripple, ...?

 

[Comcokid]

Use several diodes in series to drop the voltage. Forward voltage drop will vary some with current and temperature, but figure 0.6 Volts for each diode.

The Maxim MAX1615 has 8uA quiscent, 4-28 Vin, but is 30mA max out. The Seiko S-812C series is 1uA, 16Vin max, but is 50 to 75mA max out.

 

[felixc]

What about the LP2989 fdrom National?

 

[walker1]

With the TC55 (and other fixed voltage 3 pin regulators) you should be able to use much the same regulation as for LM317.
That is, one resistor from output to the GND pin and another from the GND pin to actual GND.

I have seen it done with LM309 years back.
(10 V (I think) out instead of 5V)

There may be draw-backs, however.
Reduced stability and/or ripple reduction etc. (I don't really know

With the above coupling, you may avoid having to reduce the input voltage to 12V, but on the other hand, it could be a good (safe) idea to do it anyway.

 

[ScottyUK]

A variation on Walker1's method which works nicely uses a suitable zener from the regulator ground pin to the circuit ground (cathode to regulator ground pin), and a resistor connected from the regulator input to the regulator ground pin to provide bias current for the zener.




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Do it right, or don't do it at all.

 

[Fabioedl]

Thanks for the replies,

felixc, the LP2989 has a quiescent current of 110uA. Way too much for my application. Thanks anyway.
I think I found another solution. I am going to use a depletion mode FET. I will connect the source to the input pin of TC55, the gate to the output and the input voltage to the FET's drain. By doing that, I will regulate the TC55' input voltage to the output voltage plus the threshold voltage of the depletion mode FET. This will create a voltage drop accross the FET.
One of our engineers showed a circuit that uses this circuit. I think it will work, but I will breadboard this and let you guys know.

Thanks anyway.

Fabioedl