communication ics application note design migration from cmx602a to CMX602B 2000 mx-com, inc. www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054 doc. # 20830135.002 4800 bethania station road, winston-salem, nc 27105-1201 usa all trademarks and service marks are held by their respective comp anies. migrating cmx602a designs to use the CMX602B device the new CMX602B device is suitable for use in new type 2 caller id designs and it is virtually 'socket compatible' with the cmx602a, its predecessor. this note describes differences between the CMX602B and the cmx602a to help ensure smooth design migration to use the CMX602B. 1 rxd output (fsk demodulator data output) state when not in use rxd is a digital output on both the cmx602a and CMX602B devices that presents received fsk data. accordingly, in both those devices, its state is not meaningful unless both (1) a valid fsk input signal is applied and (2) the fsk demodulator is enabled by placing the device into fsk receive mode. in 'non-use' situations, the rxd output of the cmx602a and CMX602B devices differs according to the following table: rxd output state condition CMX602B cmx602a not in fsk receive mode (including zero power mode) 0 (low) 1 (high) in fsk receive mode but without valid fsk signal applied indeterminate indeterminate this difference in the two devices' functions can be seen in their data bulletin system signals figures. in general, end product designs should not rely upon the static output state of an fsk demodulator unless it is enabled and a valid signal is applied. accordingly, it is expected that few cmx602a-based designs, if any, will be affected by this difference. 2 operating characteristics changes four specifications and one related note were slightly revised. the revisions, described below, are minor and so not expected to affect most designs. operating characteristics cmx602a CMX602B min. typ. max. units min. typ. max. units tone alert detector to ensure detection : 'low' tone frequency deviation from nominal 20 hz 0.5 % 'high' tone frequency deviation from nominal 30 hz 0.5 % 2750hz tone level with respect to 2130hz tone level -7.0 7.0 db -6.0 +6.0 db fsk receiver acceptable twist (mark level with respect to space level) v23 -7.0 7.0 db -6.0 -6.0 db operating characteristics note 4 cmx602a: "for v dd = 5.0v with equal tones?" CMX602B: "for v dd = 3.3v with equal tones?"
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