Datasheet

µSOP
2 7 SQW/INTX2
1 8 V
CC
+
X1
SCLV
BACKUP
3 6
SDAGND
TOP VIEW
4 5
DS1339B
PIN NAME FUNCTION
1 X1
ConnectionsforStandard32.768kHzQuartzCrystal.Theinternaloscillatorcircuitryisdesignedfor
operationwithacrystalhavingaspeciedloadcapacitance(C
L
)of6pF.
Formoreinformationaboutcrystalselectionandcrystallayoutconsiderations,seetheApplications
Information
sectionandrefertoApplicationNote58:Crystal Considerations with Dallas Real-Time Clocks.
2 X2
3 V
BACKUP
SecondaryPowerSupply.Supplyvoltagemustbeheldbetween1.3Vand3.7Vforproperoperation.
This pin can be connected to a primary cell, such as a lithium coin cell. Additionally, this pin can be
connected to a rechargeable cell or a super cap when used in conjunction with the trickle-charge
feature.DiodesshouldnotbeplacedinseriesbetweenthebackupsourceandtheV
BACKUP
input,
orimproperoperationwillresult.Ifabackupsupplyisnotrequired,V
BACKUP
mustbegrounded.UL
recognizedtoensureagainstreversechargingcurrentwhenusedwithaprimarylithiumcell.Formore
information, visit www.maximintegrated.com/qa/info/ul.
4 GND Ground
5 SDA
SerialDataInput/Output.SDAistheinput/outputpinfortheI
2
C serial interface. The SDA pin is an open-
drainoutputandrequiresanexternalpullupresistor.Thepullupvoltagemaybeupto5.5Vregardlessof
thevoltageonV
CC
.
6 SCL
SerialClockInput.SCLisusedtosynchronizedatamovementontheI
2
C serial interface. The pull up
voltagemaybeupto5.5VregardlessofthevoltageonV
CC
.
7
SQW/INT
Square-Wave/InterruptOutput.Programmablesquare-waveorinterruptoutputsignal.TheSQW/INT pin
isanopen-drainoutputandrequiresanexternalpullupresistor.Thepullupvoltagemaybeupto5.5V
regardlessofthevoltageonV
CC
. If not used, this pin may be left unconnected.
8 V
CC
PrimaryPowerSupply.Whenvoltageisappliedwithinnormallimits,thedeviceisfullyaccessibleanddata
canbewrittenandread.WhenabackupsupplyisconnectedandV
CC
isbelowV
PF
, reads and writes are
inhibited.ThetimekeepingandalarmfunctionsoperatewhenthedeviceispoweredbyV
CC
orV
BACKUP
.
DS1339B Low-Current, I
2
C, Serial Real-Time Clock
For High-ESR Crystals
www.maximintegrated.com
MaximIntegrated │ 7
Pin Description
Pin Conguration