Rev 3; 1/06
2
I C, 32-Bit Binary Counter Watchdog RTC with
Trickle Charger and Reset Input/Output
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 Laboratory (UL) Recognized
Applications
Portable Instruments
Point-of-Sale Equipment
Medical Equipment
Typical Operating Circuit
V
CC
V
CC
Telecommunications
RPU = t /C
r
B
CRYSTAL
RPU RPU
V
CC
V
X1
X2
CC
2
*Purchase of I C components of Maxim Integrated Products,
SQW
Inc., or one of its sublicensed Associated Companies, conveys
SCL
SDA
2
a license under the Philips I C Patent Rights to use these com-
CPU
2
ponents in an I C system, provided that the system conforms
DS1374
2
to the I C Standard Specification as defined by Philips.
INT
RST
INT
PRIMARY
BATTERY,
V
BACKUP
RST
RECHARGEABLE
BATTERY, OR
SUPER CAPACITOR
GND
N.O.
PUSHBUTTON
RESET
Pin Configurations appear at the end of the data sheet.
Ordering Information
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
-40°C to +85°C
PART
DS1374C-18
VOLTAGE (V)
PIN-PACKAGE
16 SO (300 mils)
16 SO (300 mils)
16 SO (300 mils)
16 SO (300 mils)
16 SO (300 mils)
16 SO (300 mils)
TOP MARK**
DS1374C-18
DS1374C-18
DS1374C-3
DS1374C-3
DS1374C-33
DS1374C-33
1.8
1.8
3.0
3.0
3.3
3.3
3.3
DS1374C-18#
DS1374C-3
DS1374C-3#
DS1374C-33
DS1374C-33#
DS1374C-33/T&R
16 SO (300 mils)/Tape and Reel
DS1374C-33
Ordering Information continued at end of 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.
**A "#" anywhere on the top mark denotes a RoHS-compliant package.
______________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.