Page 10
June 1999 TOKO, Inc.
TK15324
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 TK15324M
can be changed by high level.
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
μ
s typically.
APPLICATION
Figure 13 illustrates an example of a typical application.
The standard application is to use direct coupling at the
inputs and capacitor coupling at the outputs of the
TK15324M. For characteristics of distortion and dynamic
range versus R
, refer to the graphs in the Typical Perfor-
mance Characteristics. The TK15324M can be used at the
capacitor coupling too, but then the bias supply is neces-
sary from outside. If capacitor coupling is desired, then it
is recommended to use a built-in bias type. DC input bias
voltage of the TK15324M is V
CC
/2 V.
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
TK15324M 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.
Key in
to Logic
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