Device with constant voltage drop in the mA to uA range
John Duffy wrote 09/02/2023 at 05:10 • 0 pointsDoes anyone know of a part that will drop a constant voltage (shooting for about 2 or 3V) while passing ~3uA through ~5mA. So like a zener would work except that below a few hundred uA they tend to start to drop towards 0V drop. Trying to avoid using an opamp for this, but could use a fet or something.
Doesn't have to be super well controlled, so if it's like 2V at 5uA and 3V at 5mA that's fine, I just need a couple volts drop to have overhead for something.
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You can use a Shunt Voltage Regulator for this purpose. They are designed to drop a constant voltage across a load while allowing current to pass through. In your case, you can select a shunt voltage regulator with a voltage rating close to your desired 2-3V and a low dropout voltage. Below a certain current, they act as a pass-through, and as the current increases, they start to regulate the voltage. https://mickeyminors.pk/
Make sure to check the datasheet of the specific regulator you choose for its dropout voltage characteristics to ensure it meets your requirements.
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You have the option of utilizing just one MAX6008. This component functions as a 2.5V shunt reference and operates with a mere 1uA current. Although the maximum specified operating current is 2mA, the datasheet illustrates a typical graph showcasing it running at 5mA. The absolute maximum operating current is 20mA, and it's reasonably priced, costing less than $1.
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You could use a single MAX6008. It is a 2.5V shunt reference with a 1uA operating current. Max specified operating current is 2mA, but datasheet shows typical graph with it operating at 5mA. Abs. Max operating current is 20mA. It's pretty cheap < $1.
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REF1112 could do it. Voltage is 1.25V, so you'd need 2 in series.
https://www.ti.com/product/REF1112
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Absolute legend, thanks Paul!
That is exactly what I was looking for!
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