Z86E30/E31/E40
Z8 4K OTP Microcontroller
Zilog
PIN FUNCTIONS
R//W Read/Write (output, write Low). The R//W signal is
Low when the CCP is writing to the external program or
data memory (Z86E40 only).
EPROM Programming Mode
D7-D0 Data Bus. The data can be read from or written to
external memory through the data bus.
/RESET Reset (input, active Low). Reset will initialize the
MCU. Reset is accomplished either through Power-On,
Watch-Dog Timer reset, STOP-Mode Recovery, or exter-
nal reset. During Power-On Reset and Watch-Dog Timer
Reset, the internally generated reset drives the reset pin
low for the POR time. Any devices driving the reset line
must be open-drain in order to avoid damage from a pos-
sible conflict during reset conditions. Pull-up is provided in-
ternally. After the POR time, /RESET is a Schmitt-trig-
gered input.
A11-A0 Address Bus. During programming, the EPROM
address is written to the address bus.
VCC Power Supply. This pin must supply 5V during the
EPROM read mode and 6V during other modes.
/CE Chip Enable (active Low). This pin is active during
EPROM Read Mode, Program Mode, and Program Verify
Mode.
/OE Output Enable (active Low). This pin drives the direc-
tion of the Data Bus. When this pin is Low, the Data Bus is
output, when High, the Data Bus is input.
To avoid asynchronous and noisy reset problems, the
Z86E40 is equipped with a reset filter of four external
clocks (4TpC). If the external reset signal is less than 4TpC
in duration, no reset occurs. On the fifth clock after the re-
set is detected, an internal RST signal is latched and held
for an internal register count of 18 external clocks, or for
the duration of the external reset, whichever is longer. Dur-
ing the reset cycle, /DS is held active Low while /AS cycles
at a rate of TpC/2. Program execution begins at location
000CH, 5-10 TpC cycles after /RESET is released. For
Power-On Reset, the reset output time is 5 ms. The
Z86E40 does not reset WDTMR, SMR, P2M, and P3M
registers on a STOP-Mode Recovery operation.
EPM EPROM Program Mode. This pin controls the differ-
ent EPROM Program Mode by applying different voltages.
V
Program Voltage. This pin supplies the program volt-
PP
age.
/PGM Program Mode (active Low). When this pin is Low,
the data is programmed to the EPROM through the Data
Bus.
Application Precaution
/ROMless (input, active Low). This pin, when connected to
GND, disables the internal ROM and forces the device to
function as a Z86C90/C89 ROMless Z8. (Note that, when
The production test-mode environment may be enabled
accidentally during normal operation if excessive noise
surges above V occur on pins XTAL1 and /RESET.
CC
left unconnected or pulled High to V , the device func-
CC
In addition, processor operation of Z8 OTP devices may be
tions normally as a Z8 ROM version).
affected by excessive noise surges on the V , /CE, /EPM,
/OE pins while the microcontroller is in Standard Mode.
PP
Note: When using in ROM Mode in High EMI (noisy) envi-
ronment, the ROMless pins should be connected directly
Recommendations for dampening voltage surges in both
test and OTP mode include the following:
to V
.
CC
■ Using a clamping diode to V
CC
■ Adding a capacitor to the affected pin
Standard Mode
XTAL Crystal 1 (time-based input). This pin connects a
parallel-resonant crystal, ceramic resonator, LC, RC net-
work, or external single-phase clock to the on-chip oscilla-
tor input.
XTAL2 Crystal 2 (time-based output). This pin connects a
parallel-resonant crystal, ceramic resonator, LC, or RC
network to the on-chip oscillator output.
24
P R E L I M I N A R Y
DS97Z8X0500
ZILOG [ ZILOG, INC. ]
