
General Description
The DS1318 parallel-interface elapsed time counter
(ETC) is a 44-bit counter that maintains the amount of
time that the device operates from main and/or backup
power or during an external event. The internal
frequency of the counter clock is 4.096kHz, which pro-
vides a 244s resolution and a maximum count of over
136 years. A built-in power-sense circuit detects power
failures, automatically switches to the backup supply,
and controls the timer. If an external event timer is
desired, the control input EXT can control the counter
operation. An open-drain output provides an interrupt,
and a square-wave output provides a programmable
square wave. The DS1318 is accessed through a byte-
wide parallel interface, and operates over the industrial
temperature range.
Applications
Power Meters
Industrial Controls
Servers
Features
Byte-Wide Parallel Interface
44-Bit Binary Counter Provides Timer with 244s
Resolution
Automatic Power-Fail Detect and Switch Circuitry
Selects Power Source from the Primary Power
and the Battery, and Write Protects the Internal
Registers
Internal Power-Fail Circuit Allows Timer to
Provide Primary or Battery Operation Times
Timer can Alternately Provide an Event Timer of
Either an Active-High or Active-Low Pulse
Interrupt Output Generated Periodically or When
the Upper 32 Bits of the Counter Match an Alarm
Register
Square-Wave Output with 16 Selectable
Frequencies from 32.768kHz to 0.5Hz
+3.3V Operation
Industrial Temperature Range: -40°C to +85°C
Underwriters Laboratories (UL) Recognized
DS1318
Parallel-Interface Elapsed Time Counter
______________________________________________
Maxim Integrated Products
1
DS1318
GND
24
23
22
21
20
19
18
17
16
15
X1
TOP VIEW
X2
VBAT
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
TSSOP
(4.4mm)
DQ2
DQ1
DQ0
A0
A1
A2
A3
1
+
2
3
4
5
10
9
8
7
6
11
12
14
13
SQW
IRQ
EXT
GND
Pin Configuration
Ordering Information
DS1318
-
CPU
VCC
DQ–DQ7
A3–A0
GND
RPU
SQW
X1
IRQ
WE
OE
CE
X2
EXT
EXTERNAL
COUNTER
ENABLE
(EVENT TIMER)
0.1
μF
VBAT
Typical Operating Circuit
19-5664; Rev 1; 12/10
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
PART
TEMP RANGE
PIN-PACKAGE
DS1318E+
-40°C to +85°C
24 TSSOP
DS1318E+T&R
-40°C to +85°C
24 TSSOP
+
Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.