CD4046 Question
in [Design]
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From: Jim Thompson on 23 Feb 2010 15:41 On Tue, 23 Feb 2010 13:31:14 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >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 Just looked up a data sheet. The "extra" D-flop is theoretically a "lock detector"... known by the State of Thompson to be a fraud ;-) ...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: Chris on 23 Feb 2010 16:13 On Feb 23, 12:41 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- Web-Site.com> wrote: > On Tue, 23 Feb 2010 13:31:14 -0700, Jim Thompson > > > > <To-Email-Use-The-Envelope-I...(a)My-Web-Site.com> wrote: > >On Tue, 23 Feb 2010 12:14:02 -0800, Tim Wescott <t...(a)seemywebsite.now> > >wrote: > > >>Jim Thompson wrote: > >>> On Tue, 23 Feb 2010 11:06:08 -0800, Tim Wescott <t...(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 > > Just looked up a data sheet. The "extra" D-flop is theoretically a > "lock detector"... known by the State of Thompson to be a fraud ;-) > > ...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 athttp://www.analog-innovations.com| 1962 | > > I love to cook with wine. Sometimes I even put it in the food. What would be a good way to indicate lock? I would like to have an LED indicating a lock condition. Also, I was thinking of using a 555 to shut the PLL off when there is no input signal present. This is needed for my application. I would have the 555 hold for 1 period of the input frequency. If no signal is detected in that time frame, I would have the INHIBIT go to logic 1 and shut off the loop. Thanks, Chris
From: Ban on 23 Feb 2010 16:43 Chris wrote: >> >> Just looked up a data sheet. The "extra" D-flop is theoretically a >> "lock detector"... known by the State of Thompson to be a fraud ;-) >> >> ...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 athttp://www.analog-innovations.com| 1962 | >> >> I love to cook with wine. Sometimes I even put it in the food. > > What would be a good way to indicate lock? I would like to have an LED > indicating a lock condition. > > Also, I was thinking of using a 555 to shut the PLL off when there is > no input signal present. This is needed for my application. I would > have the 555 hold for 1 period of the input frequency. If no signal > is detected in that time frame, I would have the INHIBIT go to logic 1 > and shut off the loop. > well, the lock detector will need some '123 retriggerable Monoflop or similar, a 555 is here not so good. And this works only with phase detector2. Get the datasheet of the 74HC7046, it has a lock detector but needs still the 74123 to get a static output signal. With the PD2 your frequency goes 30% below the lock range without input signal. So the hold time must be longer than that. If you shut off the pll how do you detect anything on the input? ciao Ban
From: Jim Thompson on 23 Feb 2010 16:48 On Tue, 23 Feb 2010 22:43:56 +0100, "Ban" <bansuri(a)web.de> wrote: >Chris wrote: >>> >>> Just looked up a data sheet. The "extra" D-flop is theoretically a >>> "lock detector"... known by the State of Thompson to be a fraud ;-) >>> >>> ...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 athttp://www.analog-innovations.com| 1962 | >>> >>> I love to cook with wine. Sometimes I even put it in the food. >> >> What would be a good way to indicate lock? I would like to have an LED >> indicating a lock condition. >> >> Also, I was thinking of using a 555 to shut the PLL off when there is >> no input signal present. This is needed for my application. I would >> have the 555 hold for 1 period of the input frequency. If no signal >> is detected in that time frame, I would have the INHIBIT go to logic 1 >> and shut off the loop. >> >well, the lock detector will need some '123 retriggerable Monoflop or >similar, a 555 is here not so good. And this works only with phase >detector2. Get the datasheet of the 74HC7046, it has a lock detector but >needs still the 74123 to get a static output signal. With the PD2 your >frequency goes 30% below the lock range without input signal. So the hold >time must be longer than that. If you shut off the pll how do you detect >anything on the input? > >ciao Ban > A method of lock detection for PLL's that actually reach a zero-phase-error lock has eluded designers since I was a kid :-) ...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: Phil Hobbs on 23 Feb 2010 17:04
On 2/23/2010 4:13 PM, Chris wrote: > On Feb 23, 12:41 pm, Jim Thompson<To-Email-Use-The-Envelope-I...(a)My- > Web-Site.com> wrote: >> On Tue, 23 Feb 2010 13:31:14 -0700, Jim Thompson >> >> >> >> <To-Email-Use-The-Envelope-I...(a)My-Web-Site.com> wrote: >>> On Tue, 23 Feb 2010 12:14:02 -0800, Tim Wescott<t...(a)seemywebsite.now> >>> wrote: >> >>>> Jim Thompson wrote: >>>>> On Tue, 23 Feb 2010 11:06:08 -0800, Tim Wescott<t...(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 >> >> Just looked up a data sheet. The "extra" D-flop is theoretically a >> "lock detector"... known by the State of Thompson to be a fraud ;-) >> >> ...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 athttp://www.analog-innovations.com| 1962 | >> >> I love to cook with wine. Sometimes I even put it in the food. > > What would be a good way to indicate lock? I would like to have an LED > indicating a lock condition. > > Also, I was thinking of using a 555 to shut the PLL off when there is > no input signal present. This is needed for my application. I would > have the 555 hold for 1 period of the input frequency. If no signal > is detected in that time frame, I would have the INHIBIT go to logic 1 > and shut off the loop. > > Thanks, > Chris With phase-frequency detectors it's pretty easy--the output goes to the rail when it's out of lock, so a window comparator works well. The 4046 also has the "phase pulses" output that (very roughly) tells you what the phase error is, so you can filter that and use a comparator. I don't think that works as well as the window comparator method. With an XOR gate or diode mixer PD, you need a second PD plus a 90 degree phase shift. One excellent method is to use a divide-by-4 Johnson counter (aka walking ring). Run the main PD off one output and the lock detector off the other. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |