LiPo 3.3V Linear Regulation - Chip Suggestions?

Question

Greetings,

I'm working with a design I developed and I'm running into the shortcomings of Inductor based regulators. I'm trying to regulate a 3.7V nom. lipo battery to 3.3V for ADC sampling of a strain gauge bridge. Unfortunately I am running into issues with noise and I believe it's due to the oscillations of the voltage regulator I am currently using, the TI TPS61200.

Does anyone know of a good linear voltage regulator that can take the 3.7-4.2 V of a LiPo and still hold a 3.3V stable output?

I've searched for some time and I am not having much luck. Perhaps I am thinking of this from the wrong approach.

Many Thanks!

mlease · Accepted Answer

Jacob, which regulator are you using? Your original post said a TPS61200 but that is a boost regulator. If your regulator has a pulse skipping mode to improve light load efficiency you should disable that if you can. It will improve efficiency but at the expense of higher ripple. For an LC filter design I've used a program called Elsie that you can download from Elsie - electrical filter design program from Tonne Software , you should be able to use the free version for what you need to do. The noise from modern DC-DC regulators is low enough for digital circuits and many analog circuits so the additional parts usually aren't required. If you just filter the power to the analog circuit you should be able to get by with physically small inductor and cap. As far as LDOs go, take a look at the TI LP2980 for just powering your analog circuit. The dropout should be below 100mV if that circuit draw is 10mA as indicated earlier. One more thing to consider would be to use an RC filter on the amplifier output but put it right at the input to your micro. That assumes the frequency of the noise is much higher than the strain gauge transitions. Mike