Page 10

June 1999 TOKO, Inc.

TK15325

KEY INPUT CIRCUIT

1ch and 2ch is separate action by each control keys. Figure

11 is an equivalence circuit of key input. When terminal of

key is the open, is outputting high level (about 1.4 V), and

then Ach input signal is outputted. The channel at TK15325M

can be changed by low level. When a control terminal is

operated to low function , sometimes may flows out

maximum values about 30

µA as current from the terminal.

For this reason, use a resistance which does not exceed

0.8 V value when attaching a resistance to the outside and

make low condition.

SWITCHING TIME

This time is the signal change response time compared to

the control key input signal. Figure 12 illustrates the timimg

chart. T = 2

µs typically.

APPLICATION

Figure 13 illustrates an example of a typical application.

The standard application is to use direct coupling at the

inputs and outputs of the TK15325M. For characteristics of

distortion and dynamic range versus R

in the Typical Performance Characteristics. The TK15325M

can be used at the capacitor coupling too, but then the bias

supply is necessary from outside.

APPLICATION INFORMATION

Figure 11

Figure 12

Figure 13

Figure 14

CROSS TALK (ISOLATION AND SEPARATION)

Figure 14 is an example of a layout pattern.

As the

TK15325M is a direct coupling type, the influence by

applications is not almost.

But, if it is coupled at the

capacitor, by high impedance at input, capacitors

acccomplishes the antenna action each other. Then in

case its parts are bigger, and the space between capacitors

is too narrow, cross talk will increase. Therefore, when

designing the print circuit pattern, separate the input

capacitors as far as possible and use smaller parts. (e.g.,

surface mount type)

Key in

Bch (Ach)

SW out

50%

Ach (Bch)

t

1OUT

2AIN

VCC

GND

2OUT

1KEY

2KEY

2BIN

1AIN

1BIN

+

RL

10 µF

1Bin

11

10

9

8

7

2 Bin

1Key

2Key

+

RL

10 µF

+

33 µF

1Ain

2Ain

VCC

VEE

+

33 µF

Key in

to Logic

i