DS1339 I

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PIN DESCRIPTION

PIN

mSOP

SO

NAME

FUNCTION

1

—

X1

2

—

X2

Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator

circuitry is designed for operation with a crystal having a specified load

DS1339. In this configuration, the X1 pin is connected to the external oscillator

signal and the X2 pin is floated.

For more information about crystal selection and crystal layout considerations,

refer to Application Note 58: Crystal Considerations with Dallas Real-Time

Clocks.

3

14

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 button 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

improper operation will result. UL recognized to ensure against reverse charging

current when used with a lithium battery If a back up supply is not required,

4

15

GND

Ground. DC power is provided to the device on these pins.

5

16

SDA

Serial Data Input/Output. SDA is the input/output pin for the I

The SDA pin is an open-drain output and requires an external pullup resistor.

6

1

SCL

Serial Clock Input. SCL is used to synchronize data movement on the serial

interface.

7

2

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.

8

3

Power Supply. DC power is provided to the device on these pins.

—

4–13

N.C.

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

TYPICAL OPERATING CIRCUIT

DS1339

4

CPU

VCC

VCC

VCC

5

6

8

12

SDA

SCL

GND

X2

X1

VCC

RPU

RPU

CRYSTAL

SQW /INT

3

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