This question has been hard to google!
I know laptop hard disk runs at 5V, my microcontroller will be 3 - 3.3V, can they be connected directly together with no voltage level convertors?
Thanks in advance! Richard.
No. Even if your micro has 5V-tolerant inputs, the hard drive is not designed for 3.3V inputs. It might work, but you'll be riding tolerances and it might easily NOT work if you change to a different hard drive. Use a level shifter like, for instance, 74LVC4245.
Most (all?) of the 1 inch drives can run on 3.3v. The Seagate ST1.2's, for example, can run on either 3.3 or 5v. Of course these all tend to be a bit on the small side, storage-wise.
I've used the 40G Hitachi Travelstar 1.8" disk drives which are designed for and work very nicely on 3.3V. I used them with a 68K micro and interface that worked off 3.3V.
Mark Borgerson
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