The DS3234 is a low-cost, extremely accurate SPI™ bus
real-time clock (RTC) with an integrated temperature-com-
pensated crystal oscillator (TCXO) and crystal. The
DS3234 incorporates a precision, temperature-compen-
sated voltage reference and comparator circuit to monitor
V
CC
. When V
CC
drops below the power-fail voltage (V
PF
),
the device asserts the
RST
output and also disables 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 µP reset. The device switches to the
backup supply input and maintains accurate timekeeping
when main power to the device is interrupted. The integra-
tion of the crystal resonator enhances the long-term accu-
racy of the device as well as reduces the piece-part count
in a manufacturing line. The DS3234 is available in com-
mercial 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.
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 Laboratories Recognized
DS3234
Ordering Information
PART
DS3234S#
DS3234SN#
TEMP RANGE
0°C to +70°C
-40°C to +85°C
PIN-
PACKAGE
20 SO
20 SO
TOP
MARK
DS3234S
DS3234SN
Applications
Servers
Telematics
Utility Power Meters
GPS
#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.
Typical Operating Circuit
TOP VIEW
V
CC
V
CC
SS
SCLK
MOSI
MISO
RST
μP
PUSH-
BUTTON
RESET
CS
SCLK
DIN
DOUT
RST
N.C.
N.C.
N.C.
N.C.
N.C.
V
CC
INT/SQW
32kHz
V
BAT
V
PU
CS 1
N.C. 2
32kHz 3
V
CC
4
INT/SQW 5
RST 6
N.C.
N.C.
N.C.
N.C.
N.C. 7
N.C. 8
N.C. 9
N.C. 10
Pin Configuration
20 SCLK
19 DOUT
18 SCLK
17 DIN
DS3234
16 V
BAT
15 GND
14 N.C.
13 N.C.
12 N.C.
11 N.C.
DS3234
GND
SPI is a trademark of Motorola, Inc.
SO
______________________________________________
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.
Extremely Accurate SPI Bus RTC with
Integrated Crystal and SRAM
DS3234
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground......-0.3V to +6.0V
Junction-to-Ambient Thermal Resistance (θ
JA
) (Note 1) ...55°C/W
Junction-to-Case Thermal Resistance (θ
JC
) (Note 1) ........24°C/W
Operating Temperature Range
(noncondensing) .............................................-40°C to +85°C
Junction Temperature ......................................................+125°C
Storage Temperature Range ...............................-40°C to +85°C
Lead Temperature (soldering, 10s) .................................+260°C
Soldering Temperature (reflow, 2 times max) ....................+260°C
(See the
Handling, PC Board Layout, and Assembly
section.)
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
(T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2, 3)
PARAMETER
Supply Voltage
Logic 1 Input
CS,
SCLK, DIN
Logic 0 Input
CS,
SCLK, DIN,
RST
SYMBOL
V
CC
V
BAT
V
IH
2.0V
V
CC
3.63V
5.5V
CONDITIONS
MIN
2.0
2.0
0.7 x
V
CC
-0.3
-0.3
TYP
3.3
3.0
MAX
5.5
3.8
V
CC
+
0.3
+0.2 x
V
CC
+0.7
UNITS
V
V
V
IL
V
3.63V < V
CC
ELECTRICAL CHARACTERISTICS
(V
CC
= 2.0V to 5.5V, V
CC
= active supply (see Table 1), T
A
= -40°C to +85°C, unless otherwise noted.) (Typical values are at
V
CC
=
3.3V, V
BAT
= 3.0V,
and T
A
= +25°C, unless otherwise noted. TCXO operation guaranteed from 2.3V to 5.5V on V
CC
and 2.3V to 3.8V on
V
BAT
.) (Notes 2, 3)
PARAMETER
Active Supply Current
SYMBOL
I
CCA
CONDITIONS
SCLK = 4MHz, BSY = 0
(Notes 4, 5)
CS
= V
IH
, 32kHz output off,
SQW output off
(Note 5)
SPI bus inactive, 32kHz
output off, SQW output off
V
CC
= 3.63V
V
CC
= 5.5V
V
CC
= 3.63V
V
CC
= 5.5V
V
CC
= 3.63V
V
CC
= 5.5V
2.45
2.575
25
MIN
TYP
MAX
400
700
120
µA
160
500
600
2.70
100
µA
V
nA
UNITS
µA
Standby Supply Current
I
CCS
Temperature Conversion Current
Power-Fail Voltage
V
BAT
Leakage Current
I
CCSCONV
V
PF
I
BATLKG
(V
CC
= 2.0V to 5.5V, T
A
= -40°C to +85°C, unless otherwise noted.) (Notes 2 and 3)
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