Hi All,
A circuit needs 2.8V.
But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.It uses parallel battery and a voltage pull up IC.
Originally, I guess it is pull by capacitor, but he said that is pull by inductor.
Is that true?
Best regards, Boki.
Very likely.
Graham
"Boki" a écrit dans le message de news: snipped-for-privacy@u72g2000cwu.googlegroups.com...
Boky's style answer:
SMPS
-- Thanks, Fred.
why ?
Simple really. The batteries will produce only ~ 2.5V at end of life so a LDO regulator can't make 2.8V from that ! There is no choice but to use a step-up configuration.
Graham
In general with a decent regulator, SERIES batteries will provide a much longer lifetime than parallel ones.
Because the drawdown can be much deeper.
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The reason is because of the voltages involved, and how deeply the batteries may be discharged. Some batteries can give useable power down to very small fractions of their starting voltage. If the LDO, drops 0.1, with two 1.5v batteries, the cell voltage can only drop to 1.45v, before the rail starts to drop. A classic 'alkaline' battery, has a fairly linear discharge curve, and at 50% of it's starting capacity, will already be down to about 1.2v. They are useable down to about .9v, before being considered fully discharged. The step up system, allows the whole of this area to be used, but at the 'cost' of perhaps 5%, for the switcher losses. Conversely, the series system, only allows perhaps the first 10% of the batteries capacity to be used before the rail starts to drop. The difference between perhaps 10% 'useable', and perhaps 85%...
Best Wishes
Professional!
Thank you very much!
Best regards, Boki.
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