Electronic Components Datasheet Search |
|
CD54HCT4046A Datasheet(PDF) 4 Page - Texas Instruments |
|
|
CD54HCT4046A Datasheet(HTML) 4 Page - Texas Instruments |
4 / 28 page 4 The frequency capture range (2fC) is defined as the frequency range of input signals on which the PLL will lock if it was initially out-of-lock. The frequency lock range (2fL)is defined as the frequency range of input signals on which the loop will stay locked if it was initially in lock. The capture range is smaller or equal to the lock range. With PC1, the capture range depends on the low-pass filter characteristics and can be made as large as the lock range. This configuration retains lock behavior even with very noisy input signals. Typical of this type of phase comparator is that it can lock to input frequencies close to the harmonics of the VCO center frequency. Phase Comparator 2 (PC2) This is a positive edge-triggered phase and frequency detector. When the PLL is using this comparator, the loop is controlled by positive signal transitions and the duty factors of SIGIN and COMPIN are not important. PC2 comprises two D-type flip-flops, control-gating and a three- state output stage. The circuit functions as an up-down counter (Figure 1) where SIGIN causes an up-count and COMPIN a down-count. The transfer function of PC2, assuming ripple (fr = fi) is suppressed, is: VDEMOUT =(VCC/4π)(φSIGIN - φCOMPIN) where VDEMOUT is the demodulator output at pin 10; VDEMOUT =VPC2OUT (via low-pass filter). The average output voltage from PC2, fed to the VCO via the low-pass filter and seen at the demodulator output at pin 10 (VDEMOUT), is the resultant of the phase differences of SIGIN and COMPIN as shown in Figure 4. Typical waveforms for the PC2 loop locked at fo are shown in Figure 5. When the frequencies of SIGIN and COMPIN are equal but the phase of SIGIN leads that of COMPIN, the p-type output driver at PC2OUT is held “ON” for a time corresponding to the phase difference ( φDEMOUT). When the phase of SIGIN lags that of COMPIN, the n-type driver is held “ON”. When the frequency of SIGIN is higher than that of COMPIN, the p-type output driver is held “ON” for most of the input signal cycle time, and for the remainder of the cycle both n- and p-type drivers are “OFF” (three-state). If the SIGIN frequency is lower than the COMPIN frequency, then it is the n-type driver that is held “ON” for most of the cycle. Subsequently, the voltage at the capacitor (C2) of the low-pass filter connected to PC2OUT varies until the signal and comparator inputs are equal in both phase and FIGURE 2. PHASE COMPARATOR 1: AVERAGE OUTPUT VOLTAGE vs INPUT PHASE DIFFERENCE: VDEMOUT = VPC1OUT = (VCC/π) (φSIGIN - φCOMPIN); φDEMOUT =(φSIGIN - φCOMPIN) VCC VDEMOUT (AV) 1/2 VCC 0 0o 90o φ DEMOUT 180o FIGURE 3. TYPICAL WAVEFORMS FOR PLL USING PHASE COMPARATOR 1, LOOP LOCKED AT fo SIGIN COMPIN VCOOUT PC1OUT VCOIN VCC GND FIGURE 4. PHASE COMPARATOR 2: AVERAGE OUTPUT VOLTAGE vs INPUT PHASE DIFFERENCE: VDEMOUT = VPC2OUT = (VCC/4π) (φSIGIN - φCOMPIN); φDEMOUT =(φSIGIN - φCOMPIN) VCC VDEMOUT (AV) 1/2 VCC 0 -360o 0o φ DEMOUT 360o FIGURE 5. TYPICAL WAVEFORMS FOR PLL USING PHASE COMPARATOR 2, LOOP LOCKED AT fo SIGIN COMPIN VCOOUT PC2OUT VCOIN VCC GND PCPOUT HIGH IMPEDANCE OFF - STATE CD54HC4046A, CD74HC4046A, CD54HCT4046A, CD74HCT4046A CD54HC4046A, CD74HC4046A, CD54HCT4046A, CD74HCT4046A |
Similar Part No. - CD54HCT4046A |
|
Similar Description - CD54HCT4046A |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |