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PDF CDP1879C-1 Data sheet ( Hoja de datos )
| Número de pieza | CDP1879C-1 | |
| Descripción | CMOS Real-Time Clock | |
| Fabricantes | GE | |
| Logotipo |  |
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CMOS Peripherals
CDP1879, CDP1879C-1
iN'f
RESET
POWER DOWN
iii)
X-O/MEM
TPB/Wii
TPA
CS
A2
AI
AD
VSS'
I
2
5
4
5
6
7
B
9
10
II
12
24 VDD
23 XTAL
22 XTAL
21
CLOCK
OUT
20 DB7
19 DBS
IB DBS
17 OB4
16 OB3
15 OB2
14 OBl
15 OBO
92CS-54345RI
TERMINAL ASSIGNMENT
CMOS Real-Time Clock
Features
• CPU interface for use with general-purpose microprocessors
• Time of day/calendar
• Reads seconds, minutes, hours
• Reads day of month and month
• Alarm circuit with seconds, minutes or hours operation
• Power down mode
• Separate clock output selects 1 of 15 square wave signals
• Interrupt output activated by clock output and/or alarm circuit
• Data integrity sampling for clock rollover eliminated
• On-board oscillator 4.19 MHz, 2.09 MHz or 1.048 MHz
@ 10 V (CDP1879) crystal operation
4.19 MHz, 2.09 MHz, 1.048 MHz or 32 kHz @ 5 V
(CDP1879C-1) crystal operation
4.19 MHz, 2.09 MHz, 1.048 MHz or 32 kHz
@ 10 V or 5 V external clock operation
• Addressable in memory space or CDP1800 series I/O mode
• Low standby (timekeeping) voltage with external clock
The CDP1879 real-time clock supplies time and calendar
information from seconds to months in BCD format. It
consists of 5 separately addressable and programmable
counters that divide down an oscillator input. The clock
input can have anyone of 4 possible frequencies, allowing
flexibility in the choice of crystal or external clock sources.
Using an external 32-kHz clock source, timekeeping can be
performed down to 2.5 V (see Standby (Timekeeping)
Voltage Operation).
The device can be memory-mapped for use with any
general-purpose microprocessor and has the additional
capability of operating in the CDP1800-series input/output
mode.
The real-time clock functions as a time-of-day/calendar
with an alarm capability that can be set for combinations of
seconds, minutes or hours. Alarm time is configured by
loading alarm latches that activate an interrupt output
through a comparator when the counter and alarm latch
values are equal.
CDP1879 MODES OF OPERATION
OPERATION
FUNCTION
Fifteen selectable square-wave signals are available as a
separate clock output signal and can also activate the
interrupt output. A status register is available to indicate the
interrupt source. The value in an 8-bit control register
determines the operational characteristics of the device, by
selecting the prescaler divisor and the clock output, and
controls the load and alarm functions.
A transparent "freeze" circuit precludes clock rollover
during counter and latch access times to assure stable and
accurate values in the counters and alarm latches.
The CDP1879 is functionally identical to the CDP1879C-l.
The CDP1879 has a recommended operating voltage range
of 4 to 10.5 volts, and the CDP1879C-1 has a recommended
operating voltage range of 4 to 6.5 volts. The CDP1879 and
the CDP1879C-1 are supplied in 24-lead hermetic dual-in-
line side-brazed ceramic packages (0 suffix) and 24-lead
dual-in-line plastic packages (E suffix).
Read
1. Seconds, minutes, hours, date and month counters
2. Status register to identify interrupt source
Write
Power Down
Interrupt
1. Control register to set device operation
2. Seconds, minutes, hours, date and month counters
3. Alarm latches for alarm time
1. Tri-state interrupt output with active alarm or clock out circuitry for wake-up
control.
2. Data bus and address inputs are "DON'T CARE".
1. Clock out as source
2. Alarm time as source
3. Either ·interrupt can occur during normal or power down· mode
File Number 1360
452 ______________________________________________________________
1 page  
CMOS Peripherals
CDP1879, CDP1879C-1
PROGRAMMING MODEL
WRITE AND READ REGISTERS
BCD FORMAT
DB7
~ENS ~-5
DBO
:UNIT~ 0-9:
WRITE ONLY REGISTERS
DB7
3
2
DBO
SECONDS COUNTER (00-59)
CONTROL REGISTER
DB7
'I 'TEN~ 0-5
DBO
'UNIT~ 0-9 I I
III
II-L-J
MINUTES COUNTER (00-59)
DB7 DB6
T~NS I
0-2
J!
DBO
III
UNITS 0-9
III
I'
...J
HOURS COUNTER (01-12 or 00-23)
DB7 O=AM, 1=PM
DB6 0=24 HR, 1=12 HR
DB7 DBO
1I -'
--1
TENS
0-3
1
111I
UNITS 0-9
~IIII
1
DAY OF MONTH COUNTER
(01-28,29,30,31)
DB7
MONTH COUNTER
DBO
~, N,IT,~~,
(JAN=1 DEC=12)
DB7 O=NO LEAP YEAR
1=LEAP YEAR
REGISTER TRUTH TABLE
ADDRESS
ACTIVE SIGNAL
A2 A1
01
01
01
01
10
10
10
10
11
11
01
01
10
11
11
AD
TPB/WR
RD
0 X-
0- X
1 X-
1-
X
0 X-
0-
X
1 X-
1- X
0 X-
0-
X
0 X-
1 X-
0 X-
1 X-
1-X
DBO-DB1 - FREQUENCY SELECT
DB2 - START/STOP
DB3 - COUNTER/ALARM LATCH CONTROL
DB4-DB7 - CLOCK OUTPUT SELECT
DB7 DE30
SECONDS ALARM LATCH (00-59)
DB7
UEN~0-5;
JDBO
UNIT~0-9 1
ill
MINUTES ALARM LATCH (00-59)
/xTxlD~ OM
000
x --T-E~'N-S-,I---,~-N-,T-S'10---9'1---,
0-2
.--,---'--_-'--_ , . I I I
HOURS ALARM LATCH (01-12 or 00-23)
12 HR, DB7=0 AM, 1=PM
24 HR, DB7=X
READ ONLY REGISTER
DB7 DB6
DBO
Ix I x I 0 I 0 I 0 I 0 I 0 I 0 I
INTERRUPT STATUS REGISTER
DB7=1 ALARM CIRCUIT ACTIVATED INT.
DB6=1 CLOCK OUTPUT ACTIVATED INT.
BIT3
CONTROL
REGISTER
0
0
0
0
0
0
0
0
0
0
1
1
1
-
-
REGISTER OPERATION
Write Seconds Counter
Read Seconds Counter
Write Minutes Counter
Read Minutes Counter
Write Hours Counter
Read Hours Counter
Write Date Counter
Read Date Counter
Write Month Counter
Read Month Counter
Write Seconds Alarm Latch
Write Minutes Alarm Latch
Write Hours Alarm Latch
Write Control Register
Read Int. Status Register
456 _________________________________________________________________
5 Page 
CMOS Peripherals _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
CDP1879, CDP1879C-1
FREQUENCY INPUT REQUIREMENTS (Cont'd)
Design Considerations for Stable Crystal Oscillation
1. Stray capacitances should be minimized for best
oscillator performance. Circuit board traces should be
kept to a maximum of 1 inch, and there should be no
parallel traces.
COPle79
_~X_T_AL-+'p-"IN"'2"'34 ~~;5~~~~y
SOURCE
PIN22
XTAL
2. A signal line or power source line must not cross or go
near the oscillator circuit line.
3. It is advisable to put a 0.1-microfarad capacitor between
voo and vss of the CDP1879.
COPle79
XTAL PIN23
PARALLEL
RESONANT
CRYSTAL
~~P~IN~2=2~~~~~~IO
R.
92CS~36B86
Fig. 5 - Connections for an external-frequency source
applied to real-time clock.
92CS-36885RI
Fig. 6 - Suggested oscillator clfcuit applied to real-time
clock (see Table Ill).
STANDBY (TIMEKEEPING) VOLTAGE OPERATION
When anyone of the four specified crystals is used with the
on-board oscillator, the Real-Time Clock. can operate at a
minimum of 4 volts Voo. However, at 32 kHz the clock will
run (timekeeping only, no device READ/WRITE accesses)
down to 3 volts at -400 to +850 C and 2.5 volts at 00 to +700 C.
To achieve this low voltage operation, an external 32-kHz
clock source must be supplied at the XTAL input (see Fig.
7). The standby requirements for CHIP SELECT/DESELECT
are listed in Table IV, and Fig. 8 indicates the timing
waveforms. Fig. 9 illustrates the typical timekeeping curve
over the full temperature range.
+3V
r-----[.14~--1-.~~
5pF
1/.3 CD54/74HC04
COP 1879
92C$- 37290
Fig. 7 - Typical external clock-source CIfCUIt.
Table IV - Standby (Timekeeping) Characteristics at Full-Temperature Range
CHARACTERISTIC
Chip Deselect to Standby
(Timekeeping) Voltage Time
Recovery to Normal
Operation Time
tCSTBV
tRC
VDD
(V)
5
10
5
10
VSTBY
(V)
2.5,3
2.5,3
2.5,3
2.5,3
LIMITS
CDP1879
CDP1879C-1
Min.
Max.
Min.
Max.
2-
2-
1- - -
2-
1-
2-
--
UNITS
/1S
462 ________________________________________________________________
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet CDP1879C-1.PDF ] | |
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