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View Full Version : Applying 9V on Vin, should VDD pin be 5V?



hottnikks36
01-08-2006, 01:18 AM
Hello, I have a question regarding powering the BS2p,

i Read somewhere that if i don't have a steady 5V source, i can apply a 6V-12V on the Vin, and internal circuitry will regulate the voltage to 5V.

My question is:

If I apply a 9V voltage on the Vin pin (pin 24), and probe the VDD pin (pin 21) with a voltmeter should it read 5V ?

Simple question, I know, but it seems I can't get my stamp to work, i was wondering if it's busted.

Thanks

Tracy Allen
01-08-2006, 01:26 AM
Yes. The voltage Vdd pin 21 should be 5V, with respect to Vss pin 23. Reset pin 22 will also read 5V.

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Tracy Allen
www.emesystems.com (http://www.emesystems.com)

allanlane5
01-09-2006, 02:20 AM
Note that the voltage regulator on the BS2 is 'special', in that it can survive having +5 put IN to VDD, OR you can put 6 to 12 volts IN on Vin, and use Vdd as a +5 volt output.

But yes, when you drive Vin, the Vdd pin should go to +5 out (as compared with Vss, which should be ground).

Chris Savage
01-09-2006, 07:28 AM
Another thing to consider is that the on-board regulator can only supply about 43 mA of current, so it's not advised to use it for driving anything that would require that kind of current or more.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)