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PDF CDP6818 Data sheet ( Hoja de datos )
| Número de pieza | CDP6818 | |
| Descripción | CMOS Real-Time Clock | |
| Fabricantes | GE | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de CDP6818 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
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CMOS Peripherals _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
CDP6818
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TERMINAL ASSIGNMENT
CMOS Real-Time Clock with RAM
Features:
• Low-Power, High-Speed, High-Density CMOS
• Internal Time Base and Oscillator
• Counts Seconds, Minutes, and Hours of the Day
• Counts Days of the Week, Date, Month, and Year
• 3 V to 6 V Operation
• Time Base Input Options: 4.194304 MHz, 1.048576 MHz, or 32.768 kHz
• Time Base Oscillator for Parallel Resonant Crystals
• 40 to 200 I1W Typical Operating Power at Low Frequency Time Base
• 4.0 to 20 mW Typical Operating Power at High Frequency Time Base
• Binary or BCD Representation of Time, Calendar, and Alarm
• 12- or 24-Hour Clock with AM and'PM in 12-Hour Mode
The CDP6818 Real-Time Clock plus RAM is a peripheral
device which includes the unique MOTEL concept for use
with many 8-bit microprocessors, microcomputers, and
larger computers. This device combines three unique
features: a complete time-of-day clock with alarm and one
hundred year calendar, a programmable periodiC Interrupt
and square-wave generator, and 50 bytes of low-power
static RAM. The CDP6818 uses high-speed CMOS
technology to interface with 1 MHz processor buses, while
consuming very little power.
The Real-Time Clock plus RAM has two distinct uses. First,
it is designed as a battery powered CMOS device (in an
otherwise NMOS/TTL system) including all the common
battery backed-up functions such as RAM, time, and
calendar. Secondly, the CDP6818 may be used with a
CMOS microprocessor to relieve the software of the
timekeeping workload and to extend the available RAM of
an MPU such as the CDP6805E2.
• Daylight Savings Time Option
• Automatic End of Month Recognition
• Automatic Leap Year Compensation
• Microprocessor Bus Compatible
• MOTEL Circuit for Bus Universality
• Multiplexed Bus for Pin Efficiency
• Interfaced with Software as 64 RAM Locations
• 14 Bytes of Clock and Control Registers
• 50 Bytes of General Purpose RAM
• Status Bit Indicates Data Integrity
• Bus Compatible Interrupt Signals (IRQ)
• Three Interrupts are Separately Software Maskable and
Testable
Time-of-Day Alarm, Once-per-Second to
Once-per-Day
• Periodic Rates from 30.511s to 500 ms
• End-of-Clock Update Cycle
• Programmable Square-Wave Output Signal
• Clock Output May Be Used as Microprocessor
Clock Input
• At Time Base Frequency +1 or +4
• 24-Pin Dual-In-Line Package
IHQ
iiITEi Fig, 1 • Block diagram.
File Number 1375
560 ___________________________________________________________
1 page  
CMOS Peripherals _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
CDP6818
TABLE 1 - SWITCHING CHARACTERISTICS IVoo~5 Vdc ± 10%, VSs~O Vdc, TA~O° to 70'CI
OSCillator Startup
Reset Pulse Width
Reset Delay Time
Power Sense Pulse Width
Power Sense Delay Time
IRO Release from OS
lAO Aelease from AESET
VRT Bit Delay
Description
Symbol Min Max Unit
tRC - 100 ms
(AWL
5
-
~s
tALH 5 -
~s
tpWL 5 -
~s
tpLH 5 -
~s
tlROS -
2 ~s
tlRR -
2 ~s
tVRTO -
2 ~s
OS
AESET
\ VLOW
J VHIGH
lAO
tlROS
NOTE VHIGH=VOO-20V,VLOW=08V,lorVOO=50V ±1O%
.A.
F
\
/-
tlRR
Fig. 5 - IRQ release delay tlmmg waveforms.
VOO
2k
liRQ Only I
402 k
Test
0-----.POint
Test POint
All Outputs Except OSC2 ISee Figure 101
Fig. 6 - TTL equivalent test load.
564 _________________________________________________________________
5 Page 
___________________________________________________
CMOSPeriphe~18
CDP6818
Before Inltlahzlng the Internal registers, the SET bit In
Register B should be set to a "1" to prevent tlmel calendar
updates from occurring The program Initializes the 10 loca-
tions In the selected format (binary or BCD), then indicates
the format In the data mode (OM) bit 01 Register BAil 10
time, calendar, and alarm bytes must use the same data
mode, either binary or BCD The SET bit may now be cleared
to allow updates Once Inltlahzed the real-time clock makes
all updates In the selected data mode The data mode cannot
be changed without relnltlallzlng the 10 data bytes
Table 3 shows the binary and BCD formats of the 10 time,
calendar, and alarm locations The 24/12 bit In Register B
establishes whether the hour locations represent 1-to-12 or
O-to-23 The 24112 bit cannot be changed without relnltlahz-
Ing the hour locations. When the 12-hour format IS selected
the high-order bit of the hours byte represents PM when It IS
a "1"
The time, calendar, and alarm bytes are not always ac-
cessable by the processor program Once-per-second the 10
bytes are sWitched to the update logiC to be advanced by one
second and to check for an alarm condition If any of the 10
bytes are read at this time, the data outputs are undefined
The update lockout time IS 248,.s at the 4 194304 MHz and
1 048567 MHz time bases and 1948 ,.s for the 3276B kHz
time base The Update Cycle section shows how to accom-
modate the update cycle In the processor program
o $00
14
BytH<,
13 00
14 OE
50
ByleS
User
RAM
63 $3F
0 Seconds
1 Sec Alarm
2 Minutes
3 Min Alarm
4 Hours
5 Hr Alarm
6 Day of Wk
7 Date of Mo
8 Month
9 Year
10 Register A
.11 Register 8
12 Register C
13 Register 0
$00
01
02
03
04 Binary
05 or BCD
Contents
06
07
08
09
OA
08
OC
$00
FIg. 15 - Address map.
TABLE 3 - TIME, CALENDAR, AND ALARM DATA MODES
Address
Location
0
1
2
3
4
5
6
7
8
9
Function
Seconds
Seconds Alarm
Minutes
Minutes Alarm
Hours
f12 Hour Model
Hours
124 Hour Model
Hours Alarm
112 Hour Model
Hours Alarm
124 Hour Model
Day of the Week
Sunday= 1
Day of the Mo,1th
Month
Year
Decimal
Range
0-59
0-59
0-59
0-59
1-12
0-23
1-12
0-23
Range
Binary Data Mode BCD Data Mode
$00-$38
$00-$59
$00-$38
$00-$59
$00-$38
$00-$59
$00-$38
$00-$59
$Ol-$OC (AM) and $01-$12 IAMI and
$81-$8C fPMI
$81-$92IPMI
Example"
Binary
BCD
Data Mode Data Mode
15 21
15 21
3A 58
3A 58
05 05
$00-$17
$00-$23
05 05
$Ol-$OC lAM I and $01-$12 IAMI and
$81-$8C !PMI
$81-$92 IPMI
05
05
$00-$17
$00-23
05 05
1-7 $01-$07
1-31 $Ol-$lF
1-12 $Ol-$OC
0-99 $00-$63
$01-$07 05 05
$01-$31 OF 15
$01-$12
02 02
$00-$99 4F 79
"Example 55821 Thursday February 15 1979 (Time IS A M I
570 _______________________________________________________________
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet CDP6818.PDF ] | |
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