TMP88CU74F Datasheet, PDF (124/132 Pages) Toshiba Semiconductor – CMOS 8-BIT MICROCONTROLLER

TMP88CU74
2. Port PD
VFT output and usual input/output are controlled by VSEL of VFT control
register in bits. When a pin which is pulled down to pin VKK is used as usual
output or input, the following cautions are required.
(a) When outputting
When level “L” is output, a port which is pulled down to pin VKK is pin VKK
voltage. Such processes as clamping with the diode as shown in figure 2.13.8. (a)
are necessary to prevent pin VKK voltage applying to the external circuit.
(b) When inputting
When the external data is input, the port output latch is cleared to “0”.
The input threshold is the same as that of the other usual input/output port.
However it is necessary to drive RK (typ. 80 kΩ) sufficiently because of pulled
down to pin VKK.
VDD
VDD
R
R_K
R
R_K
V_KK
R1
V_KK
R1
(a) At output
(b) At input
Figure 2.13.8 External Circuit Interface
88CU74-124
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