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Hello, About Vrh / Vrl on mc9s12dp256, does it neccessary to use a voltage reference IC for a precise ATD conversion or does power supply voltage is sufficient as evaluation boards seems done? What is the current of Vrh ? Is there any internal regulator of Vrh voltage? Thank you for your answer that conditions my new design. Florent VERRIERE J. SAURON S.A. / Micro Plus |
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Reference Vrh on mc9s12dp256
Started by ●October 25, 2002
Reply by ●October 25, 20022002-10-25
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I try to use ratiometric designs for my A/D sources. In that manner the precise value of the reference is not critical. In a current design, for example, Vrh is connected to Vcc via a PolySwitch fuse (to prevent circuit damage of someone shorts the external Vrh line) and Vrl is connected to analogue ground. I then use precision potentiometers (which by definition are ratiometric devices) and in one case I have been able to find a pressure transducer with a 0.5V to 4.5V ratiometric output. Good luck, Bob Smith --- Avoid computer viruses, Practice safe hex --- -- Specializing in small, cost effective embedded control systems -- Robert L. (Bob) Smith Smith Machine Works, Inc. 9900 Lumlay Road Richmond, VA 23236 804/745-1065 ----- Original Message ----- From: "Florent VERRIERE" <> To: <> Sent: Friday, October 25, 2002 4:46 AM Subject: [68HC12] Reference Vrh on mc9s12dp256 > Hello, > > About Vrh / Vrl on mc9s12dp256, does it neccessary to use a voltage reference IC for a precise ATD conversion or does power supply voltage is sufficient as evaluation boards seems done? > What is the current of Vrh ? > Is there any internal regulator of Vrh voltage? > Thank you for your answer that conditions my new design. > Florent VERRIERE > J. SAURON S.A. / Micro Plus > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > |
Reply by ●October 25, 20022002-10-25
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Robert smith, I understand but my question is about Vcc is more dependant of temperature and some other tolerance like resistor,.. A voltage reference assure the system to have a certain precision depending of the component you choice . Florent. ----- Original Message ----- From: "Robert Smith" <> To: <> Sent: Friday, October 25, 2002 1:54 PM Subject: Re: [68HC12] Reference Vrh on mc9s12dp256 > I try to use ratiometric designs for my A/D sources. In that manner the > precise value of the reference is not critical. In a current design, for > example, Vrh is connected to Vcc via a PolySwitch fuse (to prevent circuit > damage of someone shorts the external Vrh line) and Vrl is connected to > analogue ground. I then use precision potentiometers (which by definition > are ratiometric devices) and in one case I have been able to find a pressure > transducer with a 0.5V to 4.5V ratiometric output. > > Good luck, Bob Smith > > --- Avoid computer viruses, Practice safe hex --- > > -- Specializing in small, cost effective > embedded control systems -- > Robert L. (Bob) Smith > Smith Machine Works, Inc. > 9900 Lumlay Road > Richmond, VA 23236 804/745-1065 > > ----- Original Message ----- > From: "Florent VERRIERE" <> > To: <> > Sent: Friday, October 25, 2002 4:46 AM > Subject: [68HC12] Reference Vrh on mc9s12dp256 > > Hello, > > > > About Vrh / Vrl on mc9s12dp256, does it neccessary to use a voltage > reference IC for a precise ATD conversion or does power supply voltage is > sufficient as evaluation boards seems done? > > What is the current of Vrh ? > > Is there any internal regulator of Vrh voltage? > > Thank you for your answer that conditions my new design. > > > > > > Florent VERRIERE > > J. SAURON S.A. / Micro Plus > > > > > > > > > > > > > > > > -------------------- > > > > > > > > ">http://docs.yahoo.com/info/terms/ > > > > > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ > |
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