4.0
TA = 25°C
3.5 RL = OPEN
3.0
2.5
TIP–TO–VEE
VEE = – 24 V
TIP–TO–VEE
VEE = – 42 V
2.0
1.5
1.0
5.0
RING–TO–GROUND
RING–TO–GROUND
VEE = – 24 V
VEE = – 42 V
7.0
9.0
11
RS, SENSE RESISTANCE (kΩ)
Figure 11. Fault Threshold (On–Hook) versus RS
3.0
VEE = – 28 V
TA = 25°C
2.4 RING–TO–GROUND
AND/OR TIP–TO–VEE
1.8
RS = 11 k
9.1 k
1.2
7.5 k
0.6
5.1 k
0
0
200
400
600
800
RL, LOOP RESISTANCE (Ω)
Figure 13. Fault Threshold (Off–Hook)
versus Loop Resistance
1.0
TA = 25°C
200 Ω < RL < 800 Ω
0.8 (SEE TEXT)
0.6
RING–TO–VEE
0.4
VEE = – 24 V
0.2
RING–TO–VEE
VEE = – 42 V
TIP–TO–GROUND
– 24 V ≤ VEE ≤ – 42 V
0
5.0
7.0
9.0
11
RS, SENSE RESISTANCE (kΩ)
Figure 15. Fault Threshold (Off–Hook) versus RS
3.0
VEE = – 42 V
TA = 25°C
9.1 k
2.4 RING–TO–GROUND
AND/OR TIP–TO–VEE
7.5 k
1.8
1.2 RS = 11 k
5.1 k
0.6
0
0
500
1000
1500
2000
RL, LOOP RESISTANCE (Ω)
Figure 12. Fault Threshold (Off–Hook)
versus Loop Resistance
3.0
VEE = – 24 V
TA = 25°C
2.4 RING–TO–GROUND
AND/OR TIP–TO–VEE
1.8
RS = 11 k
9.1 k
1.2
7.5 k
0.6
5.1 k
0
0
200
400
600
800
RL, LOOP RESISTANCE (Ω)
Figure 14. Fault Threshold (Off–Hook)
versus Loop Resistance
80
4–WIRE
60
2–WIRE
40
VEE = – 24 V
TA = 25°C
20 mA ≤ IL ≤ 40 mA
20
0.02
0.1
1.0
f, FREQUENCY (kHz)
10 20
Figure 16. VDD Ripple Rejection versus Frequency
MOTOROLA
MC33121
9