LMC567

LMC567 Low Power Tone Decoder June 1999 LMC567 Low Power Tone Decoder General Description The LMC567 is a low power general purpose LMCMOS™ tone decoder which is functionally similar to the industry standard LM567. It consists of a twice frequency voltage-controlled oscillator (VCO) and quadrature dividers which establish the reference signals for phase and amplitude detectors. The phase detector and VCO form a phase-locked loop (PLL) which locks to an input signal frequency which is within the control range of the VCO. When the PLL is locked and the input signal amplitude exceeds an internally pre-set threshold, a switch to ground is activated on the output pin. External components set up the oscillator to run at twice the input frequency and determine the phase and amplitude filter time constants. Features n n n n n n n n n n Functionally similar to LM567 2V to 9V supply voltage range Low supply current drain No increase in current with output activated Operates to 500 kHz input frequency High oscillator stability Ground-referenced input Hysteresis added to amplitude comparator Out-of-band signals and noise rejected 20 mA output current capability Block Diagram (with External Components) DS008670-1 Order Number LMC567CM or LMC567CN See NS Package Number M08A or N08E LMCMOS™ is a trademark of National Semiconductor Corp. © 1999 National Semiconductor Corporation DS008670 www.national.com Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices ar...