UPD17708 datasheet(262/356 Pages) NEC

Il numero della parte	UPD17708

Spiegazioni elettronici	4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

PDF	356 Pages

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Produttore elettronici	NEC [NEC]

Homepage	http://www.nec.com/

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262 / 356 page

262

µPD17704, 17705, 17707, 17708, 17709

17.4 Phase Comparator (

φ-DET), Charge Pump, and Unlock FF

17.4.1 Configuration of phase comparator, charge pump, and unlock FF

Figure 17-7 shows the configuration of the phase comparator, charge pump, and unlock FF.

The phase comparator compares the phase of the divided frequency “fN” output by the programmable divider with

the phase of the reference frequency “fr” output by the reference frequency generator, and outputs an up (UP) or down

(DW) request signal.

The charge pump outputs the output of the phase comparator from an error out pin (EO1 and EO0 pins).

The unlock FF detects the unlock status of the PLL frequency synthesizer.

17.4.2 through 17.4.4 describe the operations of the phase comparator, charge pump, and unlock FF.

Figure 17-7. Configuration of Phase Comparator, Charge Pump, and Unlock FF

Unlock FF

PLLUL flag

Charge pump

EO1

EO0

Reference frequency

generator

Programmable

divider

PLL disable signal

Phase comparator

( - DET)

UPD17708 Scheda tecnica(PDF) 262 Page - NEC