MT91610AQ Zarlink Semiconductor, MT91610AQ Datasheet - Page 7

• Manufacturer Part Number: MT91610AQ
• Description: Description = Short Loop Subscriber Line Interface Circuit (SLIC) With 2-4 Wire Conversion, Programmable Line Impedance, Ringing Amplification And On-hook Transmission For Did ;; Package Type = Qsop ;; No. Of Pins = 36
• Manufacturer: Zarlink Semiconductor

MT91610
Preliminary Information
Given the parameters as follows:
Ra = Rb = 100
Expected maximum loop impedance = 1.6k
including Ra and Rb)
Desirable Loop Current = 20mA
6*VREF=8V
Then | VBAT | (min) = 1600 * 0.020 +10 = 42V
Assume that the VBAT of 42V is available, then read
the value of R2 from Figure 6, which is 72k .
Step 5: Calculation Of Non-Clipping Sinusoidal
Ringing Voltage At Tip Ring (VTR)
Assume the peak Ringing Current is less than 50mA,
the ringing voltage (20Hz) at Tip and Ring is given
as:
VTR (rms) = 0.707 * {| VBAT | + VDCRI - (15.6 *
VREF)}
VDCRI= Positive DC voltage at DCRI pin
VBAT = Negative Battery voltage
VREF= Positive DC voltage at VREF pin
AC voltage at the RV input pin is therefore
RV (rms)~= VTR (rms) / 50
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