Loose ends: Power

From: sleeper75se (sleeper75se_at_yahoo.se)
Date: 2002-02-11 14:29:03


Hi all,

I'm looking into the last part of my project: power.

What do you think about this solution, going from input to output:

2x1.5V batteries is connected to a

-> step-up DC/DC converter (MAX857)
It generates 6V from input voltages as low as 0.8V.

-> post filtering (lowpass) using a passive LRC combination to get
rid of some of the ripple (300kHz)
L=100uF, R = 2 ohms, C = 100uF + 10uF attenuates 300kHz about 90dB.
That should be more than enough. :-)

-> low-dropout 5V regulator (LT1761, 20uV rms widband (<100kHz)
noise) and a big low-ESR 100uF capcitor for stability.

Since I need +/-5V I want to build two identical sections and connect
them in series, with ground in the center. A voltage inverter and a
negative LDO-regulator might sound better, but I'm having trouble
finding a good LDO-regulator for negative voltages.

Are there any potential problems with this approach?
Joerg, Jim M, what do you think?

/Andreas



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