Zilog Z8PE002 - Manual (Page 45)

Z8PE002
ZiLOG Z8Plus OTP Microcontroller
DS008700-Z8X0799 P R E L I M I N A R Y 45
INPUT PROTECTION
All I/O pins feature diode input protection. There is a diode
from the I/O pad to
V
CC
and V
SS
(Figure 43).
However, the PB5 pin features only the input protection di-
ode, from the pad to V
SS
(Figure 44).
The high-side input protection diode was removed on this
pin to allow the application of high voltage during the OTP
programming mode.
For better noise immunity in applications that are exposed
to system EMI, a clamping diode to
V
SS
from this pin should
be used to prevent entering the OTP programming mode or
to prevent high voltage from damaging this pin.
Figure 43. I/O Pin Diode Input Protection
PIN
V
CC
V
SS
Figure 44. PB5 Pin Input Protection
PIN
V
SS
PB5