Reference Port - Toshiba TC9314F Manual

Cmos digital integrated circuit silicon monolithic

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Direct division method circuit structure

This circuit bypasses the prescaler and uses the 12 bit programmable counter.

Note 26: The FM

operation. The input pins not selected by the division method are pulled down. In PLL off mode (set

by the reference port), the inputs are also pulled down.

Reference Frequency Divider

The reference frequency divider divides the frequency of the external 75 kHz crystal oscillator to generate

seven PLL reference frequency signals: 1 kHz, 3 kHz, 3.125 kHz, 5 kHz, 6.25 kHz, 12.5 kHz, and 25 kHz. The

frequency signal is selected by the reference port data.

The selected signal is supplied as the reference frequency for the phase comparator, which is described next.

The PLL is turned on or off by the reference port setting.

1. Reference Port

The reference port is an internal port used to select the reference frequency signal (from the seven

frequencies). Use the OUT1 instruction with the operand [C

contents of the reference port are all "1", the programmable counter, IF counter, and reference counter are

halted, and the PLL is turned off.

and AM

pins incorporate amps. Connecting a capacitor permits low-amplitude

5H] ( L15) to access this port. When the

TC9314F

2003-07-03

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