CMX878 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX878' PDF : 63 Pages View PDF
Line Powered Modem plus DAA
CMX878
Set the MSB (bit 7) of the ADC-REF register to 1 and all other bits to 0. Read the ADC
comparator level (bit 9 of the Line/Wakeup Event Register); if it is 1 then keep the MSB at 1,
otherwise set it to 0. Repeat this procedure for the next most significant bit (bit 6) and continue
until the LSB (bit 0). The final value represents the voltage at ADCIN, i.e. :
Measured level is:
( AVDD / 2 ) x ( final value / 255 )
Note that this configuration is intended to give an indication of the DC value of the line rather
than a precise time-quantised value (which would require a sample-and-hold circuit to be added).
Capacitor C18 de-emphasises the effect of AC signals.
© 2002 Consumer Microcircuits Limited
25
D/878/2
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