Z86C04 Datasheet, PDF (27/34 Pages) Zilog, Inc. – CMOS 8-BIT LOW-COST 1K/2K-ROM MICROCONTROLLERS

Zilog
Z86C04/C08
CMOS 8-Bit Low-Cost 1K/2K-ROM Microcontrollers
Opcode WDT (5FH). The first time opcode 5FH is execut- WDT. The WDT time-out will be SCLK x 32,512.The WDT
ed, the WDT is enabled, and subsequent execution clears will not run in Stop Mode.
the WDT counter. This has to be done within the maximum
T_WDT period; otherwise, the WDT times out and generates
Low Voltage Protection (V_LV). Maximum (V_LV) Conditions:
1
a Reset. The generated Reset is the same as a Power-On
Reset of T_POR plus 18 XTAL clock cycles. The WDT does
not work (run) in STOP mode. The WDT is disabled during
Case 1: T_A= –40°C , +85°C , Internal Clock
Frequency equal or less than 6 MHz
and after a Reset, until the WDT is enabled again.
Case 2: T_A= –40°C , +105°C , Internal Clock
Frequency equal or less than 4 MHz
Opcode WDH (4FH). When this instruction is executed it
will enable the WDT during HALT. If not, the WDT will stop Note: The internal clock frequency is one-half the external
when entering HALT. This instruction does not clear the clock frequency in standard mode.
counters, it facilitates running the WDT function during
HALT mode. A WDH instruction executed without execut-
ing WDT (5FH) has no effect.
Permanent WDT Mask Option. Only when the
The device will function normally at or above 3.0V under all
conditions. Below 3.0V, the device functions normally until
the Low Voltage Protection trip point (V_LV) is reached. The
device is guaranteed to function normally at supply
Permanent WDT Mask Option is selected, then the WDT voltages above the low voltage trip point for the
is hardwired to be enabled after reset. The WDT will temperatures and operating frequencies in Cases 1 and 2.
operate in Run mode, HALT mode, and STOP mode. The The actual low voltage trip point is a function of
Opcode 5FH is used to refresh or clear the WDT counter. temperature and process parameters (Figure 17).
The WDH instruction (4FH) has no effect The WDT will not
run in Stop Mode if the system clock driving the WDT is
selected (Z86C04 only).
2 MHz (Typical)
Temp –40C° 0°C +25°C +70°C +105°C
System Clock Driving WDT Mask Option (Z86C04 only)
V_LV 3.0 2.75 2.6
2.3
2.1
When this option is selected, the Z8’s system clock drives
the WDT instead of the on-board RC oscillator driving the
ROM Protect. ROM Protect fully protects the Z86C04/C08
ROM code from being read internally. When ROM Protect
is selected. ROM look-up tables can be used in this
mode.
VCC
(Volts)
3.2
3.0
2.8
2.6
VLV (Typical)
2.4
2.2
2.0
-60 -40 -20
0
20 40 60 80 100 120 140
Temperature (°C)
Figure 16. Typical Z86C04/C08 V_LV vs. Temperature
DS97DZ80502
PRELIMINARY
27