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ML12179-5P Fiches technique(PDF) 3 Page - LANSDALE Semiconductor Inc. |
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ML12179-5P Fiches technique(HTML) 3 Page - LANSDALE Semiconductor Inc. |
3 / 11 page www.lansdale.com Page 3 of 11 Issue A LANSDALE Semiconductor, Inc. ML12179 Figure 2. Phase/Frequency Detector and Charge Pump Waveforms fr (OSCin) H L fv (Fin ÷256) H L PDout Sourcing Current Pulse Sinking Current Pulse Z H = High voltage level; L = Low voltage level; Z = High impedance NOTES: Phase difference detection range: ∼ –2π to 2π Kp–Charge Pump Gain |Isource| |Isink| 4π ++ == ≈ |2.2| |–2.2| 4π 1.1 mA πradian Figure 1. ML12179 Expanded Block Diagram Crystal Oscillator Prescaler ÷256 Phase/Frequency Detector Charge Pump VCC OSCin OSCout 2 1 8 4 C1 C2 VCO +5.0 V fr fv VP 7 +5.0 V 6 To Loop Filter GND GNDP 5 3 NOTE: External 50 kΩ resistor across Pins 1 and 8 is necessary in either crystal or driven mode. 1000 pF Fin PDout PHASE CHARACTERISTICS The phase comparator in the ML12179 is a high speed digital phase/frequency detector circuit. The circuit determines the “lead” or “lag” phase relationship and time difference between the lead- ing edges of the VCO (fv) signal and the reference (fr) input. The detector can cover a range of ±2 π radian of fv/fr phase difference. The operation of the charge pump output is shown in Figure 2. fr lags fv in phase OR fv>fr in frequency When the phase of fr lags that of fv or the frequency of fv is greater than fr, the Do output will sink current. The pulse width will be determined by the time difference between the two rising edges. fr leads fv in phase OR fv<fr in frequency When the phase of fr leads that of fv or the frequency of fv is less than fr, the Do output will source current. The pulse width will be determined by the time difference between the two rising edges. fr = fv in phase and frequency When the phase and frequency of fr and fv are equal, the charge pump will be in a quiet state, except for current spikes when sig- nals are in phase. This situation indicates that the loop is in lock and the phase comparator will maintain the loop in its locked state. |
Numéro de pièce similaire - ML12179-5P |
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Description similaire - ML12179-5P |
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