4-104
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
Date Integrity Sampling for Clock Rollover Eliminated
On-Board Oscillator:
- Crystal Operation CDP1879 at 10V . . . . . . . 4.19MHz,
2.09MHz or 1.048MHz
- Crystal Operation CDP1879C-1 at 5V . . . . . 4.19MHz,
2.09MHz or 1.048MHz or 32kHz
- External Clock Operation at 10V or 5V. . . . 4.19MHz,
2.09MHz, 1.048MHz or 32kHz
Addressable in Memory Space or CDP1800 Series I/O
Mode
Low Standby (Timekeeping) Voltage with External Clock
Related Literature
- AN7275, Guide to the Use of CD1879 and
CDP1879C1 Real Time Clock
Pinout
CDP1879, CDP1879C-1 (PDIP, SBDIP)
TOP VIEW
Description
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 any one of 4 possible frequencies,
allowing flexibility in the choice of crystal or external clock sources.
Using an external 32kHz clock source, timekeeping can be performed
down to 2.5V (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.
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 preclude 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-1. The
CDP1879 has a recommended operating voltage range of 4V to 10.5V,
and the CDP1879C-1 has a recommended operating voltage range of
4V to 6.5V. The CDP1879 and the CDP1879C-1 are supplied in 24 lead
hermetic dual-in-line side-brazed ceramic packages (D suffix) and 24
lead dual-in-line plastic packages (E suffix
).
1
2
3
4
5
6
7
8
9
10
11
12
INT
RESET
POWER DOWN
RD
IO/MEM
TPB/WR
TPA
CS
A2
A1
A0
V
SS
16
17
18
19
20
21
22
23
24
15
14
13
V
DD
XTAL
CLK
DB7
DB6
DB4
DB2
DB1
DB0
XTAL
DB5
DB3
OUT
Ordering Information
PACKAGE
TEMP
RANGE
5V
10V
PKG.
NO.
PDIP
-40
o
C to
+85
o
C
CDP1879CE1
CDP1879E
E24.6
SBDIP
-40
o
C to
+85
o
C
CDP1879CD1
-
D24.6
Burn-In
CDP1879CD1X
-
D24.6
CDP1879 Modes of Operation
OPERATION
FUNCTION
Read
1. Seconds, minutes, hours, date and month counters
2. Status register to identify interrupt source
Write
1. Control register to set device operation
2. Seconds, minutes, hours, date and month counters
3. Alarm latches for alarm time
Power Down
1. Three-state interrupt output with active alarm or
clock out circuitry for wake-up control
2. Data bus and address inputs are "DON'T CARE"
Interrupt
1. Clock out as source
2. Alarm time as source
3. Either interrupt can occur during normal or power
down mode
March 1997
File Number
1360.2
CDP1879,
CDP1879C-1
CMOS Real-Time Clock
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
http://www.intersil.com or 407-727-9207
|
Copyright
Intersil Corporation 1999
4-105
Absolute Maximum Ratings
Thermal Information
DC Supply Voltage Range, V
DD
(Voltage referenced to V
SS
Terminal)
CDP1879 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +11V
CDP1879C-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7V
Input Voltage Range, All Inputs . . . . . . . . . . . . . . -0.5 to V
DD
+0.5V
DC Input Current, Any One Input . . . . . . . . . . . . . . . . . . . . . .
10mA
Device Dissipation Per Output Transistor . . . . . . . . . . . . . . . . 40mW
For T
A
= Full Package Temperature Range
(All Package Types)
Thermal Resistance (Typical)
JA
(
o
C/W)
JC
(
o
C/W)
PDIP Package . . . . . . . . . . . . . . . . . . .
60
N/A
SBDIP Package . . . . . . . . . . . . . . . . . .
50
12
Operating Temperature Range (T
A
)
Package Type D, H . . . . . . . . . . . . . . . . . . . . . . .-55
o
C to +125
o
C
Package Type E . . . . . . . . . . . . . . . . . . . . . . . . . . .-40
o
C to +85
o
C
Storage Temperature Range (T
STG
). . . . . . . . . . . .-65
o
C to +150
o
C
Lead Temperature (During Soldering). . . . . . . . . . . . . . . . . . +265
o
C
At Distance 1/16
1/32 in. (1.59
0.79mm) From Case for 10s Max
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Operating Conditions
at T
A
= FuIl Package-Temperature Range, Unless Otherwise specified. For maximum reliability, operating con-
ditions should be selected so that operation Is always within the following ranges:
PARAMETER
LIMITS
UNITS
CDP1879
CDPl879C-1
MIN
MAX
MIN
MAX
DC Operating Voltage Range
4
10.5
4
6.5
V
Input Voltage Range
V
SS
V
DD
V
SS
V
DD
V
DC Standby (Timekeeping) Voltage (Note 1),
V
STBY
T
A
= -40
o
C to +85
o
C (Note 2)
3
-
3
-
V
T
A
= 0
o
to +70
o
C
2.5
-
2.5
V
Clock Input Rise or Fall Time,
t
R
, t
F
V
DD
= 5V
-
10
-
10
s
V
DD
= 10V
-
1
-
-
s
NOTES:
1. Timekeeping function only, no READ/WRITE accesses, 32kHz external frequency source only, no crystal operation.
2. See Standby (Timekeeping) Voltage Operation.
CDP1879, CDP1879C-1
4-106
RESET
AM - PM
AND
HOUR LOGIC
PRESCALE
OSCILLATOR
SECOND
XTAL
XTAL
MINUTE
HOUR
DAY
MONTH
FREEZE
CIRCUIT
CALENDAR
LOGIC
PRESCALE
SELECT
CLOCK
SELECT
CONTROL
REGISTER
INT. STATUS
REGISTER
CLOCK AND
INT. LOGIC
CLOCK OUT
INT
V
DD
V
SS
I/O
INTERFACE
SECOND
LATCH
MINUTE
LATCH
HOUR
LATCH
COMPARATOR
DB0-DB7
A0
A1
A2
TPA
I-O MEM
TPB/WR
RD
CS
POWER DOWN
ADDRESS DECODE
AND
CONTROL LOGIC
8-BIT DATA BUS
FIGURE 1. REAL-TIME CLOCK FUNCTIONAL DIAGRAM
TABLE 1.
CONTROL REGISTER BIT ASSIGNMENT
Bit 1, 0
Frequency 00
Select 01
10
11
32768Hz
1.048576MHz
2.097152MHz
4.194304MHz
Bit 2
Start/Stop
1 = Start
0 = Stop
Bit 3
Counter/Latch Control
"0" = Write to Counter and disable alarm
"1" = Write to and enable alarm Clock Select
Bit 7, 6, 5, 4
0000 - disable
s
0001 - 488.2
s
0010 - 976.5
s
0011 - 1953.1
s
0100 - 3906.2
s
0101 - 7812.5
s
0110 - 15.625ms
0111 - 31.25ms
1000 - 62.5ms
1001 - 125ms
1010 - 250ms
1011 - 500ms
1100 - sec.
1101 - min.
1110 - hour
1111 - day
TABLE 2.
ADDRESSES
A2
A1
A0
Latch, Counter Seconds
0
1
0
Latch, Counter Minutes
0
1
1
Latch, Counter Hours
1
0
0
Counter, Day
1
0
1
Counter, Month
1
1
0
Control, Register
1
1
1
Status Register
1
1
1
MSB of Hours Counters (Bit 7) is an AM-PM Bit. 0 = AM; 1 = PM
Bit 6 of Hours Counter Controls 12/24 hr. 1 = 12 Hr: 0 = 24 Hr.
Status Register: Bit 7 MSB = Alarm
Interrupt Source: Bit 6 = Clock.
MSB of Month Counter (Bit 7) is a Leap Year Bit 0 = No, 1 = Yes.
CDP1879, CDP1879C-1
4-107
Static Electrical Specifications
at T
A
-40
o
C to +85
o
C V
DD
5%, Unless Otherwise Specified
PARAMETER
CONDITIONS
LIMITS
UNITS
V
O
(V)
V
IN
(V)
V
DD
(V)
CDP1879
CDPl879C-1
MIN
(NOTE 1)
TYP
MAX
MIN
(NOTE 1)
TYP
MAX
Ouiescent Device Current
I
DD
0, 5
5
-
0.01
50
-
0.02
200
A
0, 10
10
-
1
200
-
-
-
Output Low Drive (Sink)
Current, Data Bus and INT l
OL
0.4
0, 5
5
1.8
4
-
-
-
-
mA
0.5
0,10
10
3.6
7
-
-
-
-
Output High Drive (Source)
Current, Data Bus and INT I
OH
4.6
0, 5
5
-1.1
-2.3
-
-1.1
-2.3
-
9.5
0,10
10
-2.6
-4.4
-
-
-
-
Output Low Drive (Sink)
Current, Clock Out
l
OL
0.4
0, 5
5
0.6
1.4
-
0.6
1.4
-
0.5
0,10
10
1.2
3
-
-
-
-
Output High Drive (Source)
Current, Clock Out
I
OH
4.6
0, 5
5
-1.1
-2.3
-
-1.1
-2.3
-
9.5
0,10
10
-2.6
-4.4
-
-
-
-
Output Low Drive (Sink)
Current, XTAL Out
l
OL
0.4
0, 5
5
0.2
0.9
-
0.2
0.9
-
0.5
0,10
10
0.4
2
-
-
-
-
Output High Drive (Source)
Current, XTAL Out
I
OH
4.6
0, 5
5
-0.15
-0.4
-
-0.15
-0.4
-
9.5
0,10
10
-0.3
-0.7
-
-
-
-
Output Voltage
Low-Level
V
OL
(Note 2)
-
0, 5
5
-
0
0.1
-
0
0.1
V
-
0,10
10
-
0
0.1
-
-
-
Output Voltage
High Level
V
OH
(Note 2)
-
0, 5
5
4.9
5
-
4.9
5
-
-
0, 10
10
9.9
10
-
-
-
-
Input Low Voltage
V
IL
0.5, 4.5
0.5, 9.5
-
-
5
10
-
-
-
-
1.5
3
-
-
-
-
1.5
-
Input High Voltage
V
IH
0.5, 4.5
0.5, 9.5
-
-
5
10
3.5
7
-
-
-
-
3.5
-
-
-
-
-
Input Leakage Current
I
IN
Any
Input
0, 5
0, 10
5
10
-
-
-
-
1
2
-
-
-
-
1
-
A
Three-State Output
Leakage Current
I
OUT
0, 5
0,5
5
-
-
1
-
-
1
0,10
0,10
10
-
-
1
-
-
-
Operating Current (Note 3)
External Clock
32kHz
-
-
5
-
0.01
0.15
-
0.01
0.15
mA
External Clock
1MHz
-
-
5
-
0.2
1
-
0.2
1
External Clock
2MHz
-
-
5
-
0.35
1.5
-
0.35
1.5
External Clock
4MHz
-
-
5
-
0.7
2
-
0.7
2
External Clock
32kHz
-
-
10
-
0.03
0.25
-
-
-
External Clock
1MHz
-
-
10
-
0.4
2
-
-
-
External Clock
2MHz
-
-
10
-
0.8
3
-
-
-
External Clock
4MHz
-
-
10
-
1.6
4.5
-
-
XTAL Oscillator (Note 4)
32kHz
-
-
5
-
0.1
0.25
-
0.1
0.25
XTAL Oscillator (Note 4)
1MHz
-
-
5
-
0.3
0.5
-
0.3
0.5
XTAL Oscillator (Note 4)
2MHz
-
-
5
-
0.4
0.6
-
0.4
0.6
XTAL Oscillator (Note 4)
4MHz
-
-
5
-
0.6
0.8
-
0.6
0.8
XTAL Oscillator (Note 4)
1MHz
-
-
10
-
1.6
3
-
-
-
XTAL Oscillator (Note 4)
2MHz
-
-
10
-
1.8
3.5
-
-
-
XTAL Oscillator (Note 4)
4MHz
-
-
10
-
2
5
-
-
-
CDP1879, CDP1879C-1
4-108
Input Capacitance
C
IN
-
-
-
-
5
7.5
-
5
7.5
pF
Output Capacitance
C
OUT
-
-
-
-
10
15
-
10
15
Maximum Clock Rise
t
R
, t
F
and Fall Times
-
-
5
-
-
10
-
-
10
s
-
-
10
-
-
1
-
-
-
NOTES:
1. Typical values are for T
A
= 25
o
C and nominal V
DD
.
2. I
OL
= I
OH
= 1
A.
3. Operating current measured with clockout = 488.2
s and no load.
4. See Table 3 and Figure 6 for oscillator circuit information.
Static Electrical Specifications
at T
A
-40
o
C to +85
o
C V
DD
5%, Unless Otherwise Specified (Continued)
PARAMETER
CONDITIONS
LIMITS
UNITS
V
O
(V)
V
IN
(V)
V
DD
(V)
CDP1879
CDPl879C-1
MIN
(NOTE 1)
TYP
MAX
MIN
(NOTE 1)
TYP
MAX
Programming Model
WRITE AND READ REGISTERS
WRITE ONLY REGISTERS
BCD FORMAT
TENS 0-5
UNITS 0-9
DB7
DB0
SECONDS COUNTER (00-59)
TENS 0-5
DB7
DB0
MINUTES COUNTER (00-59)
DB7
DB0
HOURS COUNTER (01 - 12 OR 00-23)
DB6
X
X
TENS 0-2
DB7 0=AM, 1=PM
DB6 0=24 HR, 1=12 HR
TENS 0-3
UNITS 0-9
DB7
DB0
DAY OF MONTH COUNTER
(01-28, 29, 30, 31)
UNITS 0-9
DB7
DB0
MONTH COUNTER
X
TENS 0 OR 1
(JAN=1 DEC=12)
DB7 0=NO LEAP YEAR
1=LEAP YEAR
UNITS 0-9
UNITS 0-9
7
DB7
DB0
CONTROL REGISTER
6
5
4
3
2
1
0
DB0-DB1 - FREQUENCY SELECT
DB2 - START/STOP
DB3 - COUNTER/ALARM LATCH CONTROL
DB4-DB7 - CLOCK OUTPUT SELECT
DB7
DB0
SECONDS ALARM LATCH (00-59)
TENS 0-5
UNITS 0-9
DB7
DB0
MINUTES ALARM LATCH (00-59)
TENS 0-5
UNITS 0-9
DB7
DB0
HOURS ALARM LATCH (01-12 OR 00-23
TENS 0-2
UNITS 0-9
X
X
12 HR, DB7=0 AM, 1=PM
24 HR, DB7=X
X
DB7
DB0
READ ONLY REGISTER
X
0
0
0
0
0
0
DB6
INTERRUPT STATUS REGISTER
DB7=1 ALARM CIRCUIT ACTIVATED INT.
DB6=1 CLOCK OUTPUT ACTIVATED INT.
DB6
CDP1879, CDP1879C-1
PDF 
ZIP