DS1678
Real-Time Event Recorder
www.maxim-ic.com
GENERAL DESCRIPTION
The DS1678 real-time clock (RTC) event recorder
records the time and date of a nonperiodic,
asynchronous event each time the
INT
pin is
activated. The device records the seconds, minutes,
hours, date, day of the week, month, year, and
century when the first event occurs, and starts the 16-
bit elapsed time counter (ETC). Subsequent events
trigger the recording of the ETC into the event-log
memory. This allows for up to 1025 events to be
logged. Events can be logged while the device is
operating from either V
CC
or V
BAT
.
FEATURES
Real-Time Clock/Calendar in Binary-Coded
Decimal (BCD) Format Counts Seconds,
Minutes, Hours, Date, Month, Day of the
Week, and Year with Leap Year
Compensation and is Year 2000 Compliant
Logs Up to 1025 Consecutive Events in Read-
Only Battery-Backed Memory
User-Programmable Event Trigger can be
Triggered by the Falling Edge, Rising Edge,
or Rising and Falling Edges of the
INT
Pin
Event Counter Register Provides Data on the
Number of Events that Have Been Logged in
the Current Event-Logging Mission
Programmable RTC Alarm
32-Byte, Battery-Backed, General-Purpose
NV RAM
TYPICAL OPERATING CIRCUIT
I
2
C*
Serial Interface
Three Resolution Options for Trade-Off
Accuracy vs. Maximum Time Between Events
-40C to +85C Industrial Temperature
Range
Underwriters Laboratory (UL) Recognized
TOP MARK
††
DS1678
DS1678
DS1678S
DS1678S
DS1678S
DS1678S
ORDERING INFORMATION
PIN-PACKAGE
8 Plastic DIP
8 Plastic DIP
8 SO
8 SO
8 SO (Tape and
DS1678S/T&R
Reel)
8 SO (Tape and
DS1678S+T&R
Reel)
PART
†
DS1678
DS1678+
DS1678S
DS1678S+
†
PIN CONFIGURATION
TOP VIEW
X1
X2
V
BAT
GND
1
2
3
4
DS1678
8
7
6
5
V
CC
INT
SCL
SDA
All devices are specified over the -40°C to +85°C operating
range.
††
A “‘+” anywhere on the top mark denotes a lead(Pb)-free
device.
+
Denotes a lead(Pb)-free/RoHS-compliant device.
fd
AI
PI
tI
ds.
*
I CI
2
2
2
2
Cs
2
PDIP (300 mils)
SO (208 mils)
Cs
Cd
C
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REV: 100405
DS1678 Real-Time Event Recorder
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground……………………………………………..-0.3V to +6.0V
Operating Temperature Range (noncondensing)…………………………………………...-40°C to +85°C
Storage Temperature Range…………………………………………………………….…-55°C to +125°C
Soldering Temperature………………………………………….See IPC/JEDEC J-STD-020 Specification
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect device
reliability.
RECOMMENDED DC OPERATING CONDITIONS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at nominal
supply voltage and T
A
= +25C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
Power-Supply Voltage
Input Logic 1
Input Logic 0
Pullup Resistor Value
Battery Voltage
V
CC
V
IH
V
IL
V
PU
V
BAT
(Note 2)
(Note 2)
(Note 2)
V
CC
= 0V (Note 2)
(Note 2)
2.6
4.5
2.2
-0.3
5.0
5.5
V
CC
+
0.3
+0.8
5.5
3.5
V
V
V
V
V
DC ELECTRICAL CHARACTERISTICS
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40°C to +85°C.)
PARAMETER SYMBOL
Input Leakage
SDA, SCL
INT
I
LI
V
OL
I
CCA
V
PF
LOBAT
TRP
V
BAT
= 3.0V
1.216
x V
BAT
1
1.25 x
V
BAT
1.35
CONDITIONS
SDA output off
INT
output off
MIN
-1
10
0.4
2
1.284
x V
BAT
TYP
MAX
+1
UNITS
A
V
mA
V
Logic 0 Output
I
OL
= 4mA (SDA,
INT)
Active Supply Current
Power-Fail Voltage (Note 2)
LOBAT Trip Point
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 0V,
T
A
= -40°C to +85°C.) (Note 1)
PARAMETER SYMBOL
V
BAT
Current
(Oscillator On)
V
BAT
Current
(Oscillator Off)
I
OSC
I
BAT
CONDITIONS
MIN
TYP
300
50
MAX
500
150
UNITS
nA
nA
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DS1678 Real-Time Event Recorder
AC ELECTRICAL CHARACTERISTICS
(V
CC
= 2.6V to 5.5V or V
BAT
= 2.6V to 3.5V,
T
A
= -40°C to +85°C.) (Note 1)
PARAMETER SYMBOL
Input Capacitance
Minimum Signal Width
Minimum Event Rate
C
I
t
GLITCH
t
EVENT
CONDITIONS
INT
0.122
0.854
MIN
TYP
10
0.245
1.22
MAX
UNITS
pF
ms
ms
AC ELECTRICAL CHARACTERISTICS
(V
CC
= 4.5V to 5.5V,
T
A
= -40C to +85C.) (Note 1)
PARAMETER SYMBOL
SCL Clock Frequency
Bus Free Time Between a STOP and
START Condition
Hold Time (Repeated) START
Condition (Note 3)
LOW Period of SCL
HIGH Period of SCL
Setup Time for a Repeated START
Data Hold Time (Note 4)
Data Setup Time (Note 5)
Rise Time of Both SDA and SCL
Signals (Note 6)
Fall Time of Both SDA and SCL
Signals (Note 6)
Setup Time for STOP
Capacitive Load for Each Bus Line
(Note 6)
Input Capacitance (SCL, SDA)
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:DAT
t
SU:DAT
t
R
t
F
t
SU:STO
C
B
C
I
5
CONDITIONS
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
Fast mode
Standard mode
MIN
100
1.3
4.7
0.6
4.0
1.3
4.7
0.6
4.0
0.6
4.7
0
0
100
250
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
20 + 0.1C
B
0.6
4.0
TYP
MAX
400
100
UNITS
kHz
s
s
s
s
s
0.9
s
ns
300
1000
300
300
ns
ns
s
400
pF
pF
WARNING: Under no circumstances are negative undershoots of any amplitude allowed
when the device is in write protect.
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DS1678 Real-Time Event Recorder
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Limits at -40C are guaranteed by design and not production tested.
All voltages referenced to ground.
After this period, the first clock pulse is generated.
A device must initially provide a hold time of at least 300ns for the SDA signal to bridge the undefined region of the falling edge
of SCL. The maximum t
HD:DAT
need only be met if the device does not stretch the LOW period (t
LOW
) of the SCL signal.
A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
> 250ns must then be met. This is
automatically the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW
period of the SCL signal, it must output the next data bit to the SDA line t
R(MAX)
+ t
SU:DAT
= 1000 + 250 = 1250ns before the SCL
line is released.
Note 6:
Note 7:
C
B
—Total capacitance of one bus line in pF.
t
R
and t
F
are measured with a 1.7kΩ pullup resistor, 200pF pullup capacitor, 1.7kΩ pulldown resistor, and 5pF
pulldown capacitor.
I
2
C COMMUNICATION TIMING DIAGRAM
SDA
t
BU F
t
LOW
t
R
t
HD:STA
t
F
SCL
t
H D:STA
STOP
START
t
H D:D AT
t
SU:STO
t
HIG H
t
SU :DA T
t
SU:STA
REPEATED
START
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DS1678 Real-Time Event Recorder
BLOCK DIAGRAM
X1
X2
C
L
C
L
DIVIDER
OSCILLATOR
1Hz
REAL-TIME
CLOCK
000h
0
INT
CONTROL
LOGIC
ADDRESS
REGISTER
USER RAM
DATA LOG RAM
PORT
SCL
SDA
I
2
C SERIAL
INTERFACE
DATALOG
NV SRAM
V
CC
V
BAT
GND
POWER
CONTROL
Dallas
Semiconductor
DS1678
7FFh
2048
5 of 25
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