Tone Detector

FX105A

© 1999 Consumer Microcircuits Limited

11

D/105A/5

1.6.2.10 Calculation of PLL Filter Phase Shift

sampling clocks by the same amount. This enables the "Word" sampling filter to sample and integrate

at the maxima and minima of the input tone.

1.6.3

Replacement for FX105

Figure 6 depicts the circuit changes required to replace a FX105 with a FX105A device. A 5V zener

diode and a resistor can be used to generate a 5V supply voltage from an existing 12V supply. If the

Detect Output needs to pull up beyond the 5V supply, a transistor amplifier following the output can

be used.

Figure 6 Circuit changes for 12V to 5V conversion