KKA3010

PIN DESCRIPTION

PIN No

DESIGNATION

DESCRIPTION

1

X7 (IPU)

sense input from key matrix

2

SSM (I)

system mode selection input

3-6

Z0-Z3 (IPU)

sense inputs from key matrix

7

MDATA (OP3)

generated output data modulated with 1/2 the oscillator frequency at a 25%

duty factor

8

DATA (OP3)

generated output information

9-13

DR7-DR3 (ODN)

scan drivers

14

GND

ground (0V)

15-17

DR2-DR0 (ODN)

scan drivers

18

OSC (I)

oscillator input

19

TP2 (I)

test point 2

20

TP1 (I)

test point 1

21-27

X0-X6 (IPU)

sense inputs from key matrix

28

Vcc (I)

voltage supply

(I)

= input

(IPU)

= input with p-channel pull-up transistor

(ODN) = output with open drain n-channel transistor

(OP3)

= output 3-state

FUNCTIONAL DESCRIPTION

Keyboard operation

Every connection of one X-input and one DR-output will be recognized as a legal key operation and will cause the

device to generate the corresponding code. The same applies to every connection of one Z-input to one DR-output with

the proviso that SSM must be LOW. When SSM is HIGH a wired connection must exist between a Z-input and DR-

output. If no connection is present the system number will not be generated. Activating two or more X-inputs, Z-inputs

or Z-inputs and X-inputs at the same time is an illegal action and inhibits further activity (oscillator will not start).

When one X- or Z-input is connected to more than one DR-output, the last scan signal will be considered as legal.

The maximum value of the contact series resistance of the switched keyboard is 7K

Ω.

Inputs

In the quiescent state the command inputs X0 to X7 are held HIGH by an internal pull-up transistor. When the system

mode selection (SSM) input is LOW and the system is quiescent, the system inputs Z0 to Z3 are also held HIGH by an

internal pull-up transistor. When SSM is HIGH the pull-up transistor for the Z-inputs is switched off, in order to

prevent current flow, and a wired connection in the Z-DR matrix provides the system number.

Outputs

The output signal DATA transmits the generated information in accordance with the format illustrated by Fig.2 and

Tables 1 and 2. The code is transmitted using a biphase technique as illustrated by Fig.3. The code consists of four

parts:

• Start part - 1.5 bits (2 x logic 1)

• Control part - 1 bit

• System part - 5 bits

• Command part - 6 bits

The output signal MDATA transmits the generated information modulated by 1/12 of the oscillator frequency with a

50% duty factor.

In the quiescent state both DATA and MDATA are non-conducting (3-state outputs).

The scan driver outputs DR0 to DR7 are open drain n-channel transistors and conduct when the circuit is quiescent.

After a legal key operation the scanning cycle is started and the outputs switched to the conductive state one by one.

The DR-outputs were switched off at the end of the preceding debounce cycle.

2