19-5484; Rev 4; 8/10
2
I C, 32-Bit Binary Counter Watchdog RTC with
Trickle Charger and Reset Input/Output
DS1374
General Description
Features
♦ 32-Bit Binary Counter
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-
♦ Second Binary Counter Provides Time-of-Day
Alarm, Watchdog Timer, or NV RAM
♦ Separate Square-Wave and Interrupt Output Pins
2
♦ I C Serial Interface
♦ Automatic Power-Fail Detect and Switch Circuitry
♦ Single-Pin Pushbutton Reset Input/Open-Drain
ence and comparator circuit monitor the status of V
to
CC
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-
Reset Output
♦ Low-Voltage Operation
♦ Trickle-Charge Capability
2
grammed serially through an I C serial interface.
♦ -40°C to +85°C Operating Temperature Range
♦ 10-Pin µSOP, 16-Pin SO
♦ Available in a Surface-Mount Package with an
Integrated Crystal (DS1374C)
♦ Underwriters Laboratories (UL) Recognized
Applications
Portable Instruments
Point-of-Sale Equipment
Medical Equipment
Typical Operating Circuit
V
CC
V
CC
RPU = t /C
B
Telecommunications
r
CRYSTAL
RPU RPU
V
CC
V
X1
X2
CC
SQW
SCL
SDA
CPU
DS1374
V
INT
RST
INT
PRIMARY
BATTERY,
RECHARGEABLE
BATTERY, OR
SUPER CAPACITOR
BACKUP
RST
GND
N.O.
PUSHBUTTON
RESET
Pin Configurations appear at the end of the data sheet.
Ordering Information
PART
DS1374C-18#
DS1374C-3#
DS1374C-33#
DS1374U-18+
DS1374U-3+
DS1374U-33+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
VOLTAGE (V)
PIN-PACKAGE
16 SO (300 mils)
16 SO (300 mils)
16 SO (300 mils)
10 μSOP
TOP MARK**
DS1374C-18
DS1374C-3
DS1374C-33
DS1374-18
DS1374-3
1.8
3.0
3.3
1.8
3.0
3.3
10 μSOP
10 μSOP
DS1374-33
#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.
______________________________________________ Maxim Integrated Products
1
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.