From: Moritz v. Buttlar (info_at_baltic-microsolutions.de)
Date: 2001-02-06 10:10:34
> The AT90S4433 has a absolute maximum rating for Vcc of 6.6V.
> That means theoretically, if this voltage is exceeded only a fraction of a second
> the chip will be damaged or lose permanently performance (i.e. more current uptake,
> noise of the analog part etc.).
>
> 1)Will it be guaranteed that with full loaded bateries the 6.6 V will _never_ be
> exceeded ?
> What happens, if someone uses rechargeable alkaline batteries instead of
> NiCad-accus ?
It depends on how failproof we want the design to be. If we write in the
instructions that only rechargeable NiCd or NiMH cells are allowed than it would
be completely safe.
>
> 2)Another point is calibration voltage generation: It depends on stabilized Vcc.
> However Vcal could be (with some circuit change) derived from the reference
> voltage source.
I think that would be better. Itīs more stable as well.
> BTW. How much voltage drop has a low drop voltage regulator and how much supply
> current does it need ?
Thatīs not the problem. It takes ĩA and needs a couple ov mV voltage drop. But
most of these lowdropout regulators are in really tiny smd packages...
> Irda data transmission should get a checksum (e.g. 16bit CRC) at the end of
> each data block to check transmission quality.
Yes, something like that has to be included.
CU,
Moritz
PS: TI offers free samples of INA114 (up to 8) for development engineers :)
They are really friendly with samples now.
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