PD17012_15 Datasheet, PDF (246/320 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DIGITAL TUNING SYSTEM HARDWARE

µPD17012, 17P012
(3) Notes when diode B is not used
An example of a circuit where diode B is not used is shown below.
Suppose switches SW1, SW2, and SW4 are on, and KS7 outputs a high level, as shown below.
If diode B is missing, currents I1 and I2 flow as indicated by the dotted lines.
Consequently, a high level is input to K2 because of I2 despite that switch SW3 is off, and it is judged that SW3
is on.
SW1
SW2
SW3
SW4
I2
I1
High
Low
K2
K3
KS7
KS8
(4) Note when diode C is not used
An example of a circuit where diode C is not used is shown below.
Suppose switches SW2, SW3, and SW4 are on, and KS8 outputs a high level, as shown below.
If diode C is missing, currents I1, I2, and I3 flow as indicated by the dotted lines.
Consequently, a high level is input to K2 because of I2 despite the fact that switch SW1 is off, and it is judged
that SW1 is on.
Moreover, KS8 cannot output a high level correctly because of I3.
SW1
SW2
SW3
SW4
I2
K2
I1
K3
I3 ^Low
KS7
High
KS8
244
Data Sheet U10101EJ4V0DS