CD4046 Question
in [Design]
|
From: Chris on 23 Feb 2010 14:49 On Feb 23, 11:40 am, "Ban" <bans...(a)web.de> wrote: > Chris wrote: > > The data sheet just gives some ancient reference for finding the > > values for R1, R2, and C1. > > > Is the RC network for the VCO is (R1, R2, C1)? Would I just use the > > cutoff frequency for the R1 and C2 RC filter (i.e. fc=1/(2*Pi*R1*C1)).. > > > Thanks, > > Chris KQ6UP > > hmm, you will need also a loop-filter, so it is better to study the data > sheet until you understand what you are doing. > ciao Ban Yes, I need to figure out the values for that too. Thanks, Chris
From: Jim Thompson on 23 Feb 2010 14:53 On Tue, 23 Feb 2010 11:06:08 -0800, Tim Wescott <tim(a)seemywebsite.now> wrote: >Chris wrote: >> The data sheet just gives some ancient reference for finding the >> values for R1, R2, and C1. >> >> Is the RC network for the VCO is (R1, R2, C1)? Would I just use the >> cutoff frequency for the R1 and C2 RC filter (i.e. fc=1/(2*Pi*R1*C1)). >> >> Thanks, >> Chris KQ6UP > >Find some other data sheet? > >Some of them are more informative than others. I don't know who still >makes 'em, but I'd look to TI, ON Semiconductor, and Fairchild to start. > >The 74HC4046 is very similar (it has one more phase comparator, IIRC, >and may delete some other function) -- if you can't find what you want >in a 4046 data sheet a 74HC4046, or other 74xx4046 data sheet, may help. The 4046 has as phase detectors a conventional edge-matching PFD plus an XOR (posing as a four quadrant multiplier ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Tim Wescott on 23 Feb 2010 15:14 Jim Thompson wrote: > On Tue, 23 Feb 2010 11:06:08 -0800, Tim Wescott <tim(a)seemywebsite.now> > wrote: > >> Chris wrote: >>> The data sheet just gives some ancient reference for finding the >>> values for R1, R2, and C1. >>> >>> Is the RC network for the VCO is (R1, R2, C1)? Would I just use the >>> cutoff frequency for the R1 and C2 RC filter (i.e. fc=1/(2*Pi*R1*C1)). >>> >>> Thanks, >>> Chris KQ6UP >> Find some other data sheet? >> >> Some of them are more informative than others. I don't know who still >> makes 'em, but I'd look to TI, ON Semiconductor, and Fairchild to start. >> >> The 74HC4046 is very similar (it has one more phase comparator, IIRC, >> and may delete some other function) -- if you can't find what you want >> in a 4046 data sheet a 74HC4046, or other 74xx4046 data sheet, may help. > > The 4046 has as phase detectors a conventional edge-matching PFD plus > an XOR (posing as a four quadrant multiplier ;-) > > ...Jim Thompson Either the 74HC4046 or the 74HC7046 adds an RS flip-flop phase detector, and (I think) deletes a voltage regulator or something. At any rate, one of the 'obscure' bits of the CD4046 is deleted, and a somewhat obscure phase detector is tacked on. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
From: Jim Thompson on 23 Feb 2010 15:31 On Tue, 23 Feb 2010 12:14:02 -0800, Tim Wescott <tim(a)seemywebsite.now> wrote: >Jim Thompson wrote: >> On Tue, 23 Feb 2010 11:06:08 -0800, Tim Wescott <tim(a)seemywebsite.now> >> wrote: >> >>> Chris wrote: >>>> The data sheet just gives some ancient reference for finding the >>>> values for R1, R2, and C1. >>>> >>>> Is the RC network for the VCO is (R1, R2, C1)? Would I just use the >>>> cutoff frequency for the R1 and C2 RC filter (i.e. fc=1/(2*Pi*R1*C1)). >>>> >>>> Thanks, >>>> Chris KQ6UP >>> Find some other data sheet? >>> >>> Some of them are more informative than others. I don't know who still >>> makes 'em, but I'd look to TI, ON Semiconductor, and Fairchild to start. >>> >>> The 74HC4046 is very similar (it has one more phase comparator, IIRC, >>> and may delete some other function) -- if you can't find what you want >>> in a 4046 data sheet a 74HC4046, or other 74xx4046 data sheet, may help. >> >> The 4046 has as phase detectors a conventional edge-matching PFD plus >> an XOR (posing as a four quadrant multiplier ;-) >> >> ...Jim Thompson > >Either the 74HC4046 or the 74HC7046 adds an RS flip-flop phase detector, >and (I think) deletes a voltage regulator or something. > >At any rate, one of the 'obscure' bits of the CD4046 is deleted, and a >somewhat obscure phase detector is tacked on. A PFD can be made from nine gates (ala Treadway/Thompson) or by using a dual-D plus four 2-in-NAND's ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: Marte Schwarz on 23 Feb 2010 15:33
Hi Tim, > Find some other data sheet? Right ;-) > The 74HC4046 is very similar Right "very similar" expect the VCO. They need other values. CD4046 is much slower then 74HC4046. Earlier days I found only graphs in datasheets that leads me to useful values. Marte |