January 2000 TOKO, Inc.

Page 5

TK15210

TEST CIRCUITS AND METHODS (CONT.)

RESIDUAL NOISE (FIGURE 7)

This value is not a S/N ratio. This is a noise which occurs

from the device itself.

1) Pin 4 is in the open condition, or high level.

2) Connect an AC volt meter to Pin 2.

3) Connect a capacitor to GND from Pin 1.

4) Measure the AC voltage of Pin 2. This value is the noise

of Ach. If external noise exists, use optional filters to

eliminate it.

5) Next, connect Pin 4 to GND, or low level.

6) Remove the capacitor of Pin 1 and connect the capacitor

to Pin 3.

7) Measure in the same way.

This value is the noise level of Bch.

CROSS TALK (FIGURE 8)

This is the cross talk between Ach and Bch.

1) Pin 4 is in the open condition, or high level.

2) Connect AC volt meters to Pin 2 and Pin 3.

3) Connect a capactior and a resistance in series to GND

from Pin 1.

4) Input sine wave (10 kHz, 1 Vrms) to Pin 3.

5) Measure the level of Pin 3 and name this V3.

6) Measure the level of Pin 2 and name this V4.

7) Calculate:

Cross Talk = 20 Log

This value is the cross talk to Ach from Bch.

8) Next, connect Pin 4 to GND, or low level.

9) Change line of Pin 1 and Pin 3.

10) Input the same sine wave to Pin 1.

11) Measure and calculate in the same way.

This value is the isolation to Bch from Ach.

VCC

+

+

V

~

Figure 7

I/O TERMINAL VOLTAGE (FIGURE 9)

This is the DC voltage of the input and output.

Because the input and the output are nearly equal, only the

output is measured.

1) Pin 4 is in the open condition, or high level.

2) Connect a DC volt meter to Pin 2 and measure.

This value is the terminal voltage of Ach.

3) Next, connect Pin 4 to GND, or low level.

4) Measure in the same way.

This value is the terminal voltage of Bch.

OUTPUT TERMINAL DIFFERENCE

This is the DC output voltage difference between Ach and

Bch. This is calculated by using values measured at the

I/O Terminal Voltage.

∆ Vcent = | (Ach DC output value) - (Bch DC output

value) |

This value is the voltage difference.

VCC

+

+

V

~

5K

V

~

V4

V3

~

+

Figure 8

VCC

+

V

Figure 9