
General Description
The DS1374 is a 32-bit binary counter designed to contin-
uously count time in seconds. An additional counter gen-
erates a periodic alarm or serves as a watchdog timer. If
disabled, this counter can be used as 3 bytes of non-
volatile (NV) RAM. Separate output pins are provided for
an interrupt and a square wave at one of four selectable
frequencies. A precision temperature-compensated refer-
ence and comparator circuit monitor the status of VCC to
detect power failures, provide a reset output, and auto-
matically switch to the backup supply when necessary.
Additionally, the reset pin is monitored as a pushbutton
input for externally generating a reset. The device is pro-
grammed serially through an I2C serial interface.
Applications
Portable Instruments
Point-of-Sale Equipment
Medical Equipment
Telecommunications
Features
32-Bit Binary Counter
Second Binary Counter Provides Time-of-Day
Alarm, Watchdog Timer, or NV RAM
Separate Square-Wave and Interrupt Output Pins
I2C Serial Interface
Automatic Power-Fail Detect and Switch Circuitry
Single-Pin Pushbutton Reset Input/Open-Drain
Reset Output
Low-Voltage Operation
Trickle-Charge Capability
-40°C to +85°C Operating Temperature Range
10-Pin SOP, 16-Pin SO
Available in a Surface-Mount Package with an
Integrated Crystal (DS1374C)
Underwriters Laboratories (UL) Recognized
DS1374
I2C, 32-Bit Binary Counter Watchdog RTC with
Trickle Charger and Reset Input/Output
______________________________________________
Maxim Integrated Products
1
Ordering Information
DS1374
X1
X2
CRYSTAL
VCC
SQW
SCL
SDA
INT
RST
INT
RST
GND
VBACKUP
VCC
N.O.
PUSHBUTTON
RESET
PRIMARY
BATTERY,
RECHARGEABLE
BATTERY, OR
SUPER CAPACITOR
CPU
RPU
RPU = tr/CB
RPU
Typical Operating Circuit
19-5484; Rev 4; 8/10
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
VOLTAGE (V)
PIN-PACKAGE
TOP MARK**
DS1374C-18#
-40°C to +85°C
1.8
16 SO (300 mils)
DS1374C-18
DS1374C-3#
-40°C to +85°C
3.0
16 SO (300 mils)
DS1374C-3
DS1374C-33#
-40°C to +85°C
3.3
16 SO (300 mils)
DS1374C-33
DS1374U-18+
-40°C to +85°C
1.8
10 μSOP
DS1374-18
DS1374U-3+
-40°C to +85°C
3.0
10 μSOP
DS1374-3
DS1374U-33+
-40°C to +85°C
3.3
10 μSOP
DS1374-33
Pin Configurations appear at the end of the data sheet.
#
Denotes a RoHS-compliant device that may include lead that is exempt under RoHS requirements. The lead finish is JESD97 category
e3, and is compatible with both lead-based and lead-free soldering processes.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
**
A "#" anywhere on the top mark denotes a RoHS-compliant package. A “+” anywhere on the top mark denotes a lead(Pb)-free
package.