The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> any low power +ve only opamps?
https://designers-guide.org/forum/YaBB.pl?num=1392935586

Message started by bubbinos on Feb 20^th, 2014, 2:33pm

Title: any low power +ve only opamps?
Post by bubbinos on Feb 20^th, 2014, 2:33pm

Some friends and I are trying to build our own portable usb power pack, and are using a 3.7v 5000mah battery in the design. We'd like to charge our power pack via usb port, and are using boost converters to do most of the work. All the design has been laid out, but I thought it would be nice to have some sort of battery indicator on the unit.

My idea is to use some comparators with a 1.2V regulator and just bias each comparator. I've worked out resistor values so I can have a >80% battery line, and >50%. Anything lower will indicate <50%. Of course, this is where I've been unable to find anything useful.

The opamps would need to run off of low power (I'd like around 1V) and can't require negative voltage, since we won't have that available.
Is there anything out there that might do the job? Or perhaps a better way to design this?

Title: Re: any low power +ve only opamps?
Post by wave on Feb 21^st, 2014, 4:40pm

That should be very straight forward. Use parametric guides at the major semi suppliers. I found the LMV951 at TI. It only goes to 3V, so you would need a regulator, or atleast a diode drop on it's supply.

You might also choose a Bandgap Reference at 1.2V that works at some moderate voltage (1.8V) on our reference & R-dividers.

Wave