General Description of Function

1.

Oscillator

Since a self-bias type amplifier of CMOS inverter is contained, an oscillator can be formed by connecting a ceramic

resonator.

To minimize power dissipation, the oscillator stops oscillating except when key operation is performed.

2.

Key entry

Multi-press of key No. 20 and one of key No. 21, 22, 23 may be done, with no priority given in key entry. When the two

keys are kept pressed, a series of pulses will be output according to each key entry. If multi-press of keys which are not

allowed multi-press is done, no output will be delivered.

3.

Data organization

Data consists of 42 bits in all: 13 bits of custom code, 8 bits of key data, and their inverted codes.

Custom code

Custom code

Key data

Key data

13 bits

13 bits

8 bits

8 bits

LC7461M

No.2119-4/7