IDT1338
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM
RTC
Pin Assignment
(8-pin MSOP/8-pin SOIC)
X1
X2
V
BAT
GND
1
2
3
4
8
VCC
SQW/OUT
SCL
SDA
Pin Assignment
(16-pin SOIC)
SCL
SQW/OUT
VCC
NC
NC
NC
NC
NC
1
2
3
4
5
6
7
8
16
15
14
SDA
GND
V
BAT
NC
NC
NC
NC
NC
IDT
1338
7
6
5
IDT
1338C
13
12
11
10
9
Pin Descriptions
Pin
Number
8MSOP,
8SOIC
1
2
16SOIC
—
—
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 12.5 pF. An external
32.768 kHz oscillator can also drive the IDT1338. In this configuration, the X1 pin is connected to
the external oscillator signal and the X2 pin is left floating.
Backup Supply Input for Lithium Coin Cell or Other Energy Source. Battery voltage must be held
between the minimum and maximum limits for proper operation. Diodes placed in series
between the backup source and the V
BAT
pin may prevent proper operation. If a backup supply is
not required, V
BAT
must be connected to ground.
Connect to ground.
Serial data input/output. SDA is the input/output pin for the I
2
C serial interface. It is an open-drain
output and requires an external pull-up resistor (2 Kohm 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 Kohm typical)
3
14
V
BAT
4
5
6
7
15
16
1
2
GND
SDA
SCL
SQW/OUT Square-Wave/Output driver. When enabled and the SQWE bit set to 1, the SQW/OUT pin
outputs one of four square-wave frequencies (1 Hz, 4 kHz, 8 kHz, 32 kHz). It is an open drain
output and requires an external pull-up resistor (10K ohm typical). Operates when the device is
powered with VCC or V
BAT
.
V
CC
NC
Device power supply. When voltage is applied within specified limits, the device is fully
accessible by I
2
C and data can be written and read.
No connect. These pins are unused and must be connected to ground for proper operation.
8
—
3
4 - 13
IDT®
REAL-TIME CLOCK WITH BATTERY BACKED NON-VOLATILE RAM 2
IDT1338
REV K 032910
IDT [ INTEGRATED DEVICE TECHNOLOGY ]
