0-5V adjustable voltage regulators?

A low drop out type might be needed. ~1V to 5V adjustment more probable due to internal references typically around 1V to 1.5V. As an example:

A dc-dc converter chip like the TI MC33063 and a few external components will do it, except the minimum is 1.25 volts.

Since your current requirement is low, you can use a trick to get down below 1 volt:

Vin--[Regulator]Vout---+ | | | [Load] | | | [D1] | | | [D2] | | Gnd ------+------------+

or Vin--[Regulator]Vout---+ | | | [Load] | | +------------+ | [D1] | [D2] | Gnd ------+

If you short out D1 and D2 when Vout needed is above 1.25, you get better regulation.

Note that [Regulator] above is used to represent the complete regulator circuit and its associated components - the drawings are intended to show only the addition of the two diodes, not the complete circuit.

Ed

Most 'adjustable regulators' use a resistor divider on the output and compare to a fixed (1.2V typically) reference, so they only go to 1.2V minimum. Three-terminal and four-terminal regulators are ruled out.

The LM10 op amp includes a voltage reference, and can get close enough to the rails to do what you want, except the 100 mA part. Can you settle for 20 mA?

Add a pass transistor to the LM10 and it's easy.