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 ampli-
tude detectors. The phase detector and VCO form a
phase-locked loop (PLL) which locks to an input signal fre-
quency 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
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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
NSC [ NATIONAL SEMICONDUCTOR ]
