IDT1339

RTC

IDT®

2

IDT1339

REV S 031014

Pin Descriptions

X1

SCL

SQW/INT

GND

VCC

1

2

3

4

8

7

6

5

SDA

X2

V

BACKUP

IDT

1339

16

1

15

2

14

3

13

4

5

6

7

8

9

10

12

11

SCL

VCC

NC

NC

NC

NC

NC

NC

NC

NC

NC

NC

SDA

GND

SQW/INT

V

BACKUP

IDT

1339C

Pin

Number

Pin

Name

Pin Description/Function

MSOP

SOIC

1

—

X1

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.

2—

X2

314

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. UL recognized to ensure against reverse charged

current when used with a lithium cell.

4

15

GND

Connect to ground. DC power is provided to the device on these pins.

5

16

SDA

is an open-drain output and requires an external pull-up resistor (2 k

 typical).

6

1

SCL

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 k

 typical).

72

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 k



typical).

83

Primary power supply. When voltage is applied within normal limits, the device is fully

accessible and data can be written and read.

—

4 - 13

NC

No connect. These pins are unused and must be connected to ground.