U4089B Datasheet, PDF (9/25 Pages) ATMEL Corporation – MONOLITHIC INTEGRATED FEATUREPHONE CIRCUIT

U4089B-M
Figure 9. Reducing Speaker Amplifier Gain Results in an Equal Reduction of
AFS Attenuation
ATAFS (dB)
ATAFS_m
ATAFS_a
RATAFS
RATAFS
not usable
GSA_O
GSA_a
36 dB _{GSA (dB)}
Operating Range of
Speaker Amplifier
The basic behavior is illustrated in Figure 10. Actual values of ILON/ILOFF vary slightly
with the adjustment of the DC characteristics and the selection of the internal line
impedance.
Figure 10. Threshold of Speaker Amplifier
SA _on
4570A–CORD–04/03
SA _off
IL _off
IL _on
IL
Figure 11. Comparator Thresholds Depend on the DC Mask and Line Impedance
7
R_DC = ¥
6
R_DC = 130 kW
5
4
R_DC = 68 kW
3
10
12
14
16
I_L (mA)
18
20
ILON at line impedance = 600 W
ILOFF at line impedance = 600 W
ILON at line impedance = 900 W
ILOFF at line impedance = 900 W
9