L8708H datasheet(47/66 Pages) ZILOG

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Z86L88/81/86/87/89/73

IR/Low-Voltage Microcontroller

DS96LV00800

P R E L I M I N A R Y

Power-On Reset (POR). A timer circuit clocked by a ded-

icated on-board RC oscillator is used for the Power-On Re-

set (POR) timer function. The POR time allows VCC and

the oscillator circuit to stabilize before instruction execu-

tion begins.

The POR timer circuit is a one-shot timer triggered by one

of three conditions:

Power Fail to Power OK status including Waking up

from (VLV Standby).

Stop-Mode Recovery (if D5 of SMR = 1).

WDT Time-Out.

The POR time is a nominal 5 ms. Bit 5 of the Stop-Mode

after Stop-Mode Recovery (typical for external clock, RC,

LC oscillators).

HALT. HALT turns off the internal CPU clock, but not the

XTAL oscillation. The counter/timers and external inter-

rupts IRQ0, IRQ1, IRQ2, IRQ3, and IRQ4 remain active.

The devices are recovered by interrupts, either externally

or internally generated. An interrupt request must be exe-

cuted (enabled) to exit HALT mode. After the interrupt ser-

vice routine, the program continues from the instruction af-

ter the HALT.

STOP. This instruction turns off the internal clock and ex-

ternal crystal oscillation and reduces the standby current

to 10

µA or less. STOP mode is terminated only by a reset,

such as WDT time-out, POR, SMR, or external reset. This

causes the processor to restart the application program at

address 000CH. In order to enter STOP (or HALT) mode,

it is necessary to first flush the instruction pipeline to avoid

suspending execution in mid-instruction. To do this, the

user must execute a NOP (opcode = FFH) immediately be-

fore the appropriate sleep instruction, i.e.,

NOP

; clear the pipeline

STOP

; enter STOP mode

NOP

; clear the pipeline

HALT

; enter HALT mode

Figure 37. Oscillator Conﬁguration

XTAL1

XTAL2

XTAL1

XTAL2

XTAL1

XTAL2

XTAL1

XTAL2

Ceramic Resonator or Crystal

C1, C2 = 47 pF TYP *

f = 8 MHz

C1, C2 = 22 pF

L = 130

µH *

f = 3 MHz *

@ 3V VCC (TYP)

C1 = 33 pF *

R = 1K *

External Clock

* Preliminary value including pin parasitics

32 kHz XTAL

C1 = 20 pF, C = 33

Rd = 56 - 470K

Rf =10 M

XTAL1

XTAL2

L8708H Datasheet(PDF) 47 Page - Zilog, Inc.

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