Z86C61/62/96
CMOS Z8 Microcontroller Zilog
34 P R E L I M I N A R Y DS97Z8X1600
FUNCTIONAL DESCRIPTION (Continued)
Clock. The Z86C61/62/96 on-chip oscillator has a high-
gain, parallel-resonant amplifier for connection to a crystal,
LC, ceramic resonator, or any suitable external clock
source (XTAL1 = Input, XTAL2 = Output). The crystal
should be AT cut, 1 MHz to 20 MHz max, and series resis-
tance (RS) is less than or equal to 100 Ohms. The crystal
should be connected across XTAL1 and XTAL2 using the
recommended capacitors (10 pF < CL < 100 pF) from each
pin to device ground (Figure 27).
Note: Actual capacitor values specified by the crystal
manufacturer.
HALT. Turns off the internal CPU clock but not the XTAL
oscillation. The counter/timers and the external interrupts
IRQ0, IRQ1, IRQ2, and IRQ3 remain active. The devices
are recovered by interrupts, either externally or internally
generated. An interrupt request must be executed (en-
abled) to exit HALT mode. After the interrupt service rou-
tine, the program continues from the instruction after the
HALT.
STOP. This instruction turns off the internal clock and ex-
ternal crystal oscillation and reduces the standby current
to 5 µA (typical) or less. The STOP mode is terminated by
a reset, which causes the processor to restart the applica-
tion program at address 000CH.
In order to enter STOP (or HALT) mode, it is necessary to
first flush the instruction pipeline to avoid suspending exe-
cution in mid-instruction. To do this, the user must execute
a NOP (opcode=0FFH) immediately before the appropri-
ate sleep instruction, i.e.,
Figure 27. Oscillator Configuration
XTAL1
XTAL2
C1
C2
XTAL1
XTAL2
XTAL1
XTAL2
Ceramic Resonator
or Crystal
LC Clock
L
FF NOP ; clear the pipeline
6F STOP ; enter STOP mode
or
FF NOP ; clear the pipeline
7F HALT ; enter HALT mode
