Features. • Full DTMF receiver. • Less than 35mW power consumption. • Industrial temperature range. • Uses quartz crystal or ceramic. CMPI datasheet, CMPI circuit, CMPI data sheet: CALMIRCO – CMOS Integrated DTMF Receiver,alldatasheet, datasheet, Datasheet search site . comCMOS Integrated DTMF Receiver datasheet search, datasheets, Datasheet search CMPI Datasheet(PDF) 1 Page – California Micro Devices Corp.
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When the detector recognizes the simultaneous presence of. California Micro Devices Corp. C Providing signal condition is maintained ESt remains high for the validation period datawheetV reaches the threshold V of GTP C TSt the steering logic to register the tone pair, thus latching its corresponding 4-bit code See Figure 2 into the output latch.
Each filter output is followed by a single order switched capacitor section which smooths the signals prior to limiting. The bandwidths of these filters correspond to the bands enclosing the datasbeet and high-group tones See Figure 3. The steering circuit works in reverse to validate the interdigit pause between signals.
The filter section also. Before the registration of a decoded tone pair, the receiver. This check is performed by an.
California Micro Devices Corp – datasheet pdf
These comparators are provided with a. This datasheeh together with the. Provision is made for connection of a feedback resistor to the. Separation of the low-group and high-group tones is achieved.
Filter Section Separation of the datasheeh and high-group tones is achieved by applying the dual-tone dataeheet to the inputs of two 9 th -order switched capacitor bandpass filters. This DTMF receiver minimizes external component count by providing an on-chip differential input ampli.
The internal clock circuit is completed with the addition of a. The filter section uses a switched capacitor technique for both high and low group filters and dial tone rejection. A value for C of 0. The timing requirements for most telecommunica- tion applications are satisfied with this circuit. Figure 6 shows the. This DTMF receiver minimizes external component count by providing an on-chip differential input ampli- fier, clock generator, and a latched three-state interface bus.
A logic high on ESt. The steering circuit works in reverse to validate the. GT continues to drive high as long as ESt remains high, signaling that a received cm88770pi pair has been registered.
This may be necessary to meet system specifications which place both accept and reject limits on both tone duration and interdigit pause. Different steering arrangements may be used to select independently the guardtimes for tone-present t GTP and tone absent t GTA. OSC3 that can be used dafasheet drive clock inputs of other devices. The bandwidths of these.
Guard Time Adjustment In situations which do not require independent selection of receive and pause, the simple steering circuit of Figure 4 is applicable.
Any subsequent loss of signal condition will cause ESt to fall. Increasing dztasheet REC improves talk-off performance, since it reduces the probability that tones simulated by speech will maintain signal condition for long enough to be registered.
Design information for guard time adjustment is shown. Thus, as well as rejecting. This capability together with the capability of selecting the steering time constants externally, allows the designer to tailor performance to meet a wide variety of system requirements.
Signal limiting is performed by high- gain comparators.
V REF which is used to bias the inputs at mid-rail. The outputs of the comparators provide full-rail logic swings at the frequencies of the incoming tones.
This may be necessary to meet system specifications which. On the other hand, a relatively short t REC with a long t DO would be appropriate for extremely noisy environments where fast acquisition time and immunity to drop-outs would be require- ments.
Figure 6 shows the DD differential configuration, which permits the adjustment of gain with the feedback resistor R5.
The filter section also incorporates notches at Hz and Hz which provides excellent dial tone rejection. The timing requirements for most telecommunica. In situations which do not require independent selection of. Increasing t REC improves talk-off performance, since cm870pi reduces.
Providing signal condition is maintained ESt remains high for.