Digital programmable power with 1.8V logic to Vout = 5V

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Feb 23, 2016
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I need to switch between power sources in range about 1.8V to 3.3 or 5V.
This has to be digital programmable with 1.8V logic level.

Do you have parts available?
Or a solution how to realize?

 

Digital programmable power is not very common. Switching 5V with 1.8V logic is
not very common as well. I have two advise how it can be realized, depending on
your digital signal. Is your 1.8V logic level a simple high/low or is it more
complex like I2C for instance?

Attached are my suggestions. Both cases are two IC solutions. A single chip
solution is not available. In both cases a linear power regulator is used. With
only one input voltage you create 1.8V, 3.3V or 5V. The output voltage is set
with two external resistors. Therewith, for variing the output voltage, the
resistors must be varied. Big advantage is, you can choose the linear regulator
which is most appropriate for your load current requirements.

On left hand of attachment one resistor is replaced by a digital potentiometer.
The digital potentiometer is controlled by 1.8V logic.

On right hand a discrete resistor matrix is used. The apropriate resistor value
for each output voltage is set by switching parallel resistors on and off. The
switch is controlled by 1.8V logic.

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