DS1339A Datasheet, PDF (7/19 Pages) Maxim Integrated Products – Low-Current, I2C, Serial Real-Time Clock

DS1339A
Low-Current, I²C, Serial Real-Time Clock
Pin Configuration
TOP VIEW
X1 1
X2 2
VBACKUP 3
GND 4
+
DS1339A
µSOP
8 V_CC
7 SQW/INT
6 SCL
5 SDA
Pin Description
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 specified load capacitance (C_L) of 6pF.
For more information about crystal selection and crystal layout considerations, see the Applications
2
X2
Information section and refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks.
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
3
V_BACKUP 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.maxim-ic.com/qa/info/ul.
4
GND Ground
Serial Data Input/Output. SDA is the input/output pin for the I²C serial interface. The SDA pin is an open-
5
SDA 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 I²C serial interface. The pull up
voltage may be up to 5.5V regardless of the voltage on V_CC.
Square-Wave/Interrupt Output. Programmable square-wave or interrupt output signal. The SQW/INT pin
7
SQW/INT 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.
Primary Power Supply. When voltage is applied within normal limits, the device is fully accessible and
8
V_CC
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.
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