DS3234_07 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Extremely Accurate SPI Bus RTC with Integrated Crystal and SRAM

Rev 1; 7/07
Extremely Accurate SPI Bus RTC with
Integrated Crystal and SRAM
General Description
The DS3234 is a low-cost, extremely accurate SPI™ bus
real-time clock (RTC) with an integrated temperature-
compensated crystal oscillator (TCXO) and crystal. The
DS3234 incorporates a precision, temperature-compen-
sated voltage reference and comparator circuit to moni-
tor V_CC. When V_CC drops below the power-fail voltage
(V_PF), the device asserts the RST output and also dis-
ables read and write access to the part when V_CC drops
below both V_PF and V_BAT. The RST pin is monitored as
a pushbutton input for generating a reset externally. The
device switches to the backup supply input and main-
tains accurate timekeeping when main power to the
device is interrupted. The integration of the crystal res-
onator enhances the long-term accuracy of the device
as well as reduces the piece-part count in a manufactur-
ing line. The DS3234 is available in commercial and
industrial temperature ranges, and is offered in an
industry-standard 300-mil, 20-pin SO package.
The DS3234 also integrates 256 bytes of battery-backed
SRAM. In the event of main power loss, the contents of
the memory are maintained by the power source con-
nected to the V_BAT pin. The RTC maintains seconds,
minutes, hours, day, date, month, and year information.
The date at the end of the month is automatically adjust-
ed for months with fewer than 31 days, including correc-
tions for leap year. The clock operates in either the
24-hour or 12-hour format with AM/PM indicator. Two
programmable time-of-day alarms and a programmable
square-wave output are provided. Address and data are
transferred serially by an SPI bidirectional bus.
Applications
Servers
Utility Power Meters
Telematics
GPS
Typical Operating Circuit
V_CC
SS
SCLK
MOSI
MISO
RST
CPU
PUSH-
BUTTON
RESET
V_CC
V_PU
CS
SCLK
DIN
DOUT
RST
N.C.
N.C.
N.C.
N.C.
N.C.
V_CC
INT/SQW
32kHz
V_BAT
DS3234 _N.C.
N.C.
N.C.
GND
N.C.
Features
♦ Accuracy ±2ppm from 0°C to +40°C
♦ Accuracy ±3.5ppm from -40°C to +85°C
♦ Battery Backup Input for Continuous
Timekeeping
♦ Operating Temperature Ranges
Commercial: 0°C to +70°C
Industrial: -40°C to +85°C
♦ Low-Power Consumption
♦ Real-Time Clock Counts Seconds, Minutes,
Hours, Day, Date, Month, and Year with Leap Year
Compensation Valid Up to 2099
♦ Two Time-of-Day Alarms
♦ Programmable Square-Wave Output
♦ 4MHz SPI Bus Supports Modes 1 and 3
♦ Digital Temp Sensor Output: ±3°C Accuracy
♦ Register for Aging Trim
♦ RST Input/Output
♦ 300-Mil, 20-Pin SO Package
♦ Underwriters Laboratory (UL) Recognized
Ordering Information
PART
TEMP RANGE ^PIN-
PACKAGE
TOP
MARK
DS3234S#
0°C to +70°C 20 SO
DS3234S
DS3234SN# -40°C to +85°C 20 SO
DS3234SN
# Denotes a RoHS-compliant device that may include lead that
is exempt under the RoHS requirements. 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 device.
Pin Configuration
TOP VIEW
CS 1
N.C. 2
32kHz 3
VCC 4
INT/SQW 5
RST 6
N.C. 7
N.C. 8
N.C. 9
N.C. 10
DS3234
20 SCLK
19 DOUT
18 SCLK
17 DIN
16 V_BAT
15 GND
14 N.C.
13 N.C.
12 N.C.
11 N.C.
SPI is a trademark of Motorola, Inc.
SO
______________________________________________ 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.