z86e72 ZiLOG Semiconductor, z86e72 Datasheet - Page 69

• Manufacturer Part Number: z86e72
• Description: Otp Microcontroller
• Manufacturer: ZiLOG Semiconductor

PS008704-0507
Power-On Reset (POR)
The crystal must be connected across XTAL1 and XTAL2 using the recommended
capacitors (capacitance greater than or equal to 22 pF) from each pin to ground.
The RC oscillator configuration is an external resistor connected from XTAL1 to
XTAL2, with a frequency-setting capacitor from XTAL1 to ground (see
A timer circuit clocked by a dedicated on-board RC oscillator is used for the
Power-On Reset (POR) timer function. The POR time allows VCC and the oscilla-
tor circuit to stabilize before instruction execution begins.
The POR timer circuit is a one-shot timer triggered by one of three conditions:
•
•
•
The POR time is a nominal 5 ms. Bit 5 of the Stop-Mode Register determines
whether the POR timer is bypassed after Stop-Mode Recovery (typical for external
clock, RC, and LC oscillators).
C2
C1
C1
32 kHz XTAL
C1 = 20 pF, C = 33 pF
Rd = 56–470K
Rf = 10M
C2
Ceramic Resonator or Crystal
C1, C2 = 47pF TYP*
f = 8 MHz
Power Fail to Power OK status.
Stop-Mode Recovery (if D5 of SMR = 1).
WDT Time-Out.
Rd
Rf
XTAL2
XTAL1
Figure 38. Oscillator Configuration
XTAL2
XTAL1
* Preliminary value including pin parasitics
C2
C1
LC
C1, C2 = 22 pF
L = 130 μH*
f = 3 MHz*
L
XTAL2
XTAL1
External Clock
XTAL2
XTAL1
C1
RC
@ 3V VCC (TYP)
C1 = 33 pF*
R = 1K*
OTP Microcontroller
R
XTAL1
XTAL2
Figure
38).
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