Over-voltage?
LoopyByteloose
Posts: 12,537
I just got several SX28 Proto boards and wanted to track down the power with a VOM.
I plugged one in without any crystal or devices connected to the board and got a reading of over 7 volts DC.· My input voltage is a wall wart that reads about 14.78 volts DC, though it is rated lower [noparse][[/noparse]12 or 9 volts, I have to crawl under the desk to actually see].
The LM2940-5.0 is rated at 26volts absolute Max in its PDF.· So I didn't think there was reason to worry.
I do see that board say 6-9VDC.· And the output side regulation capacitor seems small [noparse][[/noparse]should be 22.5uf or larger according to my PDF].
Is this a defective board or did I miss something?· As it stands, the SX28 is rated at 7volts max, so I fear damage.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
I plugged one in without any crystal or devices connected to the board and got a reading of over 7 volts DC.· My input voltage is a wall wart that reads about 14.78 volts DC, though it is rated lower [noparse][[/noparse]12 or 9 volts, I have to crawl under the desk to actually see].
The LM2940-5.0 is rated at 26volts absolute Max in its PDF.· So I didn't think there was reason to worry.
I do see that board say 6-9VDC.· And the output side regulation capacitor seems small [noparse][[/noparse]should be 22.5uf or larger according to my PDF].
Is this a defective board or did I miss something?· As it stands, the SX28 is rated at 7volts max, so I fear damage.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
···················· Tropical regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Comments
I just wish the devide would shut down when power is low rather than issue trash ;-(
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
I had a very similar problem a couple of days ago!
I have a design that drives an OLED from an SX-28 and things weren't working. Threw my multimeter onto the circuit and noticed Vcc was showing nearly 4vdc instead of 3.3vdc....panicked as that's over-spec for the OLED and ripped apart a perfectly good 3.3vdc looking for the problem. [noparse];)[/noparse]
I knew the low battery indicator was lit on the multimeter, but never realized that it'd dramatically affect it's performance!
Hopefully others can avoid this issue.
-marc
I guess I'm putting this out there for comments back as much as for information on the above mentioned issue.
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John R.
8 + 8 = 10
Post Edited (John R.) : 12/31/2006 2:49:37 PM GMT