Z87C33 Datasheet, PDF (26/72 Pages) Zilog, Inc. – CMOS Z8® MCU Consumer Controller Processor

Z87C33
CMOS Z8“ MCU Consumer Controller Processor
20
programmable and is selectable by the customer at the time the ROM code is
submitted.
Notes: The RC option is available up to 4MHz. The RC oscillator
configuration must be an external resistor connected from X_IN to
X_OUT, with a frequency-setting capacitor from X_IN to Ground
(Figure 12).
For better noise immunity, the capacitors should be tied directly
to the device Ground pin (V_SS).
XTAL1
XTAL1
C1
C1
**
**
L
C2
V_SS**
XTAL2
C2
V_SS**
Ceramic
Resonator
or Crystal
C1, C2 = 47µfd*
f = 4MHz
LC Clock
C1, C2 = 22 pf
L =130 µH*
f = 3 MHz*
*Preliminary value, including pin parasitics
** Device Ground Pin
XTAL2
XTAL1
C
XTAL2
V_SS**
XTAL1
R
XTAL2
External Clock
RC Clock
@5V V_CC (TYP)
C1 = 44pF*
R = 4K ohm
f = 3 MHz*
Figure 12.Oscillator Configuration
Power-On Reset (POR). A timer circuit clocked by a dedicated on-board RC oscilla-
tor is used for the Power-On Reset (POR) timer function. The POR time allows
V_CC and the oscillator circuit to stabilize before instruction execution begins.
The POR timer circuit is a one-shot timer triggered by one of three conditions:
1. Power fail to Power OK status.
2. Stop-Mode Recovery (if D5 of SMR = 1).
3. WDT time-out.
The POR time is specified as TPOR. Bit 5 of the Stop-Mode Register determines
whether the POR timer is bypassed after Stop-Mode Recovery (typical for external
clock, RC/LC oscillators).
HALT. HALT turns off the internal CPU clock, but not the CRYSTAL oscillation.
The counter/timers, analog comparators, and external interrupts IRQ0, IRQ1,
IRQ2, and IRQ3 remain active. The devices are recovered by interrupts and are
either externally or internally generated. This also includes WDT time-out Reset
PS015601-1003