IDT1339
REAL-TIME CLOCK WITH SERIAL I
2
C INTERFACE
RTC
Pin Assignment
(8-pin MSOP/8-pin SOIC)
X1
X2
V
BACKUP
GND
1
2
3
4
8
VCC
SQW/INT
SCL
SDA
Pin Assignment
(16-pin SOIC)
SCL
SQW/INT
VCC
NC
NC
NC
NC
NC
1
2
3
4
5
6
7
8
16
15
14
SDA
GND
V
BACKUP
NC
NC
NC
NC
NC
IDT
1339
7
6
5
IDT
1339C
13
12
11
10
9
Pin Descriptions
Pin
Number
MSOP SOIC
1
2
—
—
Pin
Name
X1
X2
Pin Description/Function
Connections for standard 32.768 kHz quartz crystal. The internal oscillator circuitry is
designed for operation with a crystal having a specified load capacitance (CL) of 7 pF. An
external 32.768 kHz oscillator can also drive the IDT1339. In this configuration, the X1 pin
is connected to the external oscillator signal and the X2 pin is left floating.
Backup supply input. Supply voltage must be held between 1.3 V and 3.7 V for proper
operation. This pin can be connected to a primary cell, such as a lithium button cell.
Additionally, this pin can be connected to a rechargeable cell or a super cap that can be
charged using the trickle charger circuit. Diodes placed in series between the backup
source and the VBAT pin may prevent proper operation. If a backup supply is not required,
VBAT must be connected to ground.
Connect to ground. DC power is provided to the device on these pins.
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 pull-up resistor (2 kΩ typical).
Serial clock input. SCL is used to synchronize data movement on the serial interface. It is an
open-drain output and requires an external pull-up resistor (2 kΩ typical).
3
14
V
BACKUP
4
5
6
7
15
16
1
2
GND
SDA
SCL
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 pull-up resistor (10 kΩ
typical).
V
CC
8
—
3
4 - 13
Primary power supply. When voltage is applied within normal limits, the device is fully
accessible and data can be written and read.
No connect. These pins are unused and must be connected to ground.
NC
IDT®
REAL-TIME CLOCK WITH SERIAL I
2
C INTERFACE
2
IDT1339
REV K 032910
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
