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74VHC4046NX データシート(PDF) 1 Page - National Semiconductor (TI) |
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74VHC4046NX データシート(HTML) 1 Page - National Semiconductor (TI) |
1 / 14 page TLF11675 October 1995 74VHC4046 CMOS Phase Lock Loop General Description The 74VHC4046 is a low power phase lock loop utilizing advanced silicon-gate CMOS technology to obtain high fre- quency operation both in the phase comparator and VCO sections This device contains a low power linear voltage controlled oscillator (VCO) a source follower and three phase comparators The three phase comparators have a common signal input and a common comparator input The signal input has a self biasing amplifier allowing signals to be either capacitively coupled to the phase comparators with a small signal or directly coupled with standard input logic levels This device is similar to the CD4046 except that the Zener diode of the metal gate CMOS device has been replaced with a third phase comparator Phase Comparator I is an exclusive OR (XOR) gate It pro- vides a digital error signal that maintains a 90 phase shift between the VCO’s center frequency and the input signal (50% duty cycle input waveforms) This phase detector is more susceptible to locking onto harmonics of the input fre- quency than phase comparator I but provides better noise rejection Phase comparator III is an SR flip-flop gate It can be used to provide the phase comparator functions and is similar to the first comparator in performance Phase comparator II is an edge sensitive digital sequential network Two signal outputs are provided a comparator out- put and a phase pulse output The comparator output is a TRI-STATE output that provides a signal that locks the VCO output signal to the input signal with 0 phase shift be- tween them This comparator is more susceptible to noise throwing the loop out of lock but is less likely to lock onto harmonics than the other two comparators In a typical application any one of the three comparators feed an external filter network which in turn feeds the VCO input This input is a very high impedance CMOS input which also drives the source follower The VCO’s operating frequency is set by three external components connected to the C1A C1B R1 and R2 pins An inhibit pin is provided to disable the VCO and the source follower providing a meth- od of putting the IC in a low power state The source follower is a MOS transistor whose gate is con- nected to the VCO input and whose drain connects the De- modulator output This output normally is used by tying a resistor from pin 10 to ground and provides a means of looking at the VCO input without loading down modifying the characteristics of the PLL filter Features Y Low dynamic power consumption (VCCe45V) Y Maximum VCO operating frequency 12 MHz (VCCe45V) Y Fast comparator response time (VCCe45V) Comparator I 25 ns Comparator II 30 ns Comparator III 25 ns Y VCO has high linearity and high temperature stability Y Pin and function compatible with the 74HC4046 Commercial Package Package Description Number 74VHC4046M M16A 16-Lead Molded JEDEC SOIC 74VHC4046N N16E 16-Lead Molded DIP Note Surface mount packages are also available on Tape and Reel Specify by appending the suffix letter ‘‘X’’ to the ordering code TRI-STATE is a registered trademark of National Semiconductor Corporation C1995 National Semiconductor Corporation RRD-B30M125Printed in U S A |
同様の部品番号 - 74VHC4046NX |
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同様の説明 - 74VHC4046NX |
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