DS1339 I

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PIN DESCRIPTION

PIN

NAME

FUNCTION

µSOP

SO

1

—

X1

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 left unconnected.

For more information about crystal selection and crystal layout considerations,

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

Clocks.

2

—

X2

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

be grounded. UL recognized to ensure against reverse charging current when

used with a lithium cell. For more information, visit www.maxim-ic.com/qa/info/ul.

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 I

interface. The pull up voltage may be up to 5.5V regardless of the voltage on

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

If not used, this pin may be left unconnected.

8

3

Primary Power Supply. When voltage is applied within normal limits, the device

is fully accessible and data can be written and read. When a backup supply is

—

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

1

2

SDA

SCL

GND

X2

X1

VCC

RPU

RPU

CRYSTAL

SQW/INT

3

7

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