¡ Semiconductor

MSM6234

5/12

R1, R2, R3, R4, C1, C2, C3, C4

These are input pins of negative logic to be connected to the keyboard.

The standard 2 of 8 keyboard can be used with MSM6234RS as illustrated below.

R1 to R4 are the input pins of the row side, while C1 to C4 are the input pins of the column side. All

the pins are provided with the pull-up resistor of 20 kW to 150 kW internally.

The dual tone is output from the TONE OUT pin, by setting both of a row input and a column input

to the ground voltage.

The Table 1 (See Note) shows the relation between the nominal frequency and the tone output

frequency, while the Table 2 (See Note) shows the input condition of R1 to R4 pins and C1 to C4 pins.

• Refer to the Table 1 and Table 2

Table-1

R

MSM6234RS

R = 20 kW to 150 kW

R1

R

R2

R

R3

R

R4

R

C4

R

C3

R

C2

R

C1

A

B

C

D

3

6

9

#

2

5

8

0

1

4

7

*

ROW

COL

2 of 8 keyboard

Effective Input

Nominal

Frequency

Tone Output

Frequency

Accuracy (%)

Remarks

R1

R2

R3

R4

(ROW)

C1

C2

C3

C4

(COLUMN)

697 Hz

Low Group

High Group

770 Hz

852 Hz

941 Hz

1209 Hz

1336 Hz

1477 Hz

1633 Hz

699.1 Hz

766.2 Hz

847.4 Hz

948.0 Hz

1215.9 Hz

1331.7 Hz

1471.9 Hz

1645.0 Hz

+0.30%

+0.73%

+0.57%

+0.74%

–0.49%

–0.54%

–0.32%

–0.35%