UPD17015 Datasheet, PDF(57/120 Page) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR PORTABLE RADIOS

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UPD17015 Datasheet, PDF (57/120 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR PORTABLE RADIOS

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ÂµPD17015

11.4 PHASE COMPARATOR (Ï-DET), CHARGE PUMP AND UNLOCK DETECTION BLOCK

11.4.1 Configuration of Phase Comparator, Charge Pump and Unlock Detection Block

Fig. 11-6 shows the configuration of the phase comparator, charge pump and unlock detection block.

The phase comparator compares the phase of the divided frequency (fN) signal output from the programmable

divider and that of the reference frequency (fr) signal output from the reference frequency generator and outputs an

up request signal (UP) or down request signal (DW).

The charge pump outputs the output of the phase comparator from the error out pin (EO pin).

The unlock detection block detects the PLL frequency synthesizer unlocked state from UP and DW.

Sections 11.4.2 to 11.4.4 describe the operation of the phase comparator, charge pump, and unlock detection

block.

Fig. 11-6 Phase Comparator, Charge Pump and Unlock Detection Block

PLLUL flag

Reference

frequency

generator

Programmable

divider

Phase comparator

(Ï -DET)

PLL disable signal

Unlock

detection

block

Charge pump

▷