參數(shù)資料
型號: VT82885
廠商: Electronic Theatre Controls, Inc.
英文描述: Real Time Clock
中文描述: 實時時鐘
文件頁數(shù): 2/16頁
文件大小: 72K
代理商: VT82885
2
VT82885
Real Time Clock
VIA Technologies, Inc.
WR#
RD#
RESET#
IRQ#
SQW
V
CC
OPERATION
- Write Strobe
- Read Strobe
- Reset Input
- Interrupt Request Output
- Square Wave Output
- +5 Volt Supply
GND
X1, X2
- Ground
- 32.768 kHz Crystal Connec-
tions
- +3 Volt Battery Input
- RAM Clear
V
BAT
#
RCLR#
The block diagram in Figure 1 shows the
pin connections with the major internal func-
tions of the VT82885. The following para-
graphs describe the function of each pin.
FIQURE 1: BLOCK DIAGRAM VT82885
POWER-DOWN/POWER-UP
CONSIDERATIONS
The Real Time Clock function will continue
to operate and all of the RAM, time, calen-
dar and alarm memory locations remain
nonvolatile regardless of the level of the V
CC
input. When V
CC
is applied to the VT82885
and reaches a level of greater than 4.25
volts, the device becomes ac-cessible after
100 ms, provided that the oscillator is
running and the oscillator countdown chain
is not in reset (see Register A). This time
period allows the system to stabilize after
OSC
+8
+64
+64
PERIODIC INTERUPT SQUARE WAVE
SELECTOR
SQUARE
WAVE OUT
POWER
SWITCH
AND
WRITE
PROTECT
BUS
INTERFACE
CLOCK/
CALENDAR
UPDATE
BCD/
BINARY
INCREMENT
REGISTERS A,B,C,D
CLOCK, CALENDAR
AND ALARM RAM
USER RAM
114 BYTES
X2
X1
GND
AS
RD#
AD0-
AD7
WR#
V
BAT
V
CC
CS#
CS#
SQW
IRQ#
RESET#
RCLR#
POK
V
CC
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