TCM1520A

RING DETECTOR

SCTS005B – OCTOBER 1984 – REVISED DECEMBER 1990

5

POST OFFICE BOX 655303

POST OFFICE BOX 1443

APPLICATION INFORMATION

AC

INPUT

AC

INPUT

5-V OUTPUT

C FILTER

COMMON

1

8

6

37

4

TCM1520A

C2 = 10

µF,

50 V

R1 = 2.2 k

Ω

VIrms = 40 V to 150 V,

15.3 Hz to 68 Hz

R2 = 2.2 k

Ω

VID

C1 = 0.47

µF,

350 V

TIL181

To Isolated

Output

Figure 4. Isolated Configuration

AC

INPUT

AC

INPUT

5-V OUTPUT

C FILTER

COMMON

1

8

6

37

4

TCM1520A

C2 = 10

µF,

50 V

R1 = 2.2 k

Ω

VIrms = 40 V to 150 V,

15.3 Hz to 68 Hz

10 k

Ω

VID

C1 = 0.47

µF,

350 V

INVERTING

OUTPUT

Output

2

Figure 5. Nonisolated Configuration

NOTE: See Table 1 for component functions.

TABLE 1. COMPONENT FUNCTIONS

COMPONENT

FUNCTION

R1

Limits current into SCR during high-voltage transients and aids in dial-pulse rejection.

R2

Limits current into light-emitting diode.

C1

Blocks dc-battery voltage in standby and aids in filtering dial pulses. Smaller values of C1

improve tapping immunity.

C2

Stores energy from the ring signal to power the 5-V regulator.

Optocoupler

Provides ground and transient isolation between the host system and the telephone line.