Post by thread:opamp

Depending on what you need your -5 volts for, you could just use a charge pump max861, ad660, etc which will give you a "digital" -5 volt level. If you need -5v as an analog or variable level this obviously won't work. I don't know of any single volt opamps that would do this but my knowledge of opamps is limited. Wendall {Quote hidden}> -----Original Message----- > From: pic microcontroller discussion list > [spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU]On Behalf Of H. Ross > Sent: Thursday, December 17, 1998 7:09 AM > To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Subject: opamp > > > Does anyone out their now how to use a single +5v opamp to > convert, input > +5v to be converted to -5v at the output. (help, help). > > //HR >

>Does anyone out their now how to use a single +5v opamp to convert, input >+5v to be converted to -5v at the output. (help, help). AFAIK, opamps need a negative supply voltage (-5V) to produce a negative voltage out. There are options to get a negative voltage with a single positive supply, though. In fact you can buy voltage inverters for just that purpose. They're usually charge pump devices, I believe. Dave Johnson

Forget the op amp. for currents up to about 40 mA use a 7660 or 7662. -----Original Message----- From: H. Ross <rossioKILLspamHOEFTD.RENO.NV.US> To: .....PICLISTKILLspam.....MITVMA.MIT.EDU <EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU> Date: Thursday, December 17, 1998 11:15 AM Subject: opamp >Does anyone out their now how to use a single +5v opamp to convert, input >+5v to be converted to -5v at the output. (help, help). > >//HR >

>>Does anyone out their now how to use a single +5v opamp to convert, input >>+5v to be converted to -5v at the output. (help, help). The Analog Devices AMD660 and 8660 might suit your needs. The 8660 even has a shutdown pin so you can reduce power consumption should you desire.