DS1305

2 of 21

ORDERING INFORMATION

PART

TEMP RANGE

PIN-PACKAGE

TOP MARK*

DS1305

0°C to +70°C

16 DIP (300 mils)

DS1305

DS1305E+

0°C to +70°C

20 TSSOP (173 mils)

DS1305

DS1305EN+

-40°C to +85°C

20 TSSOP (173 mils)

DS1305N

DS1305EN+T&R

-40°C to +85°C

20 TSSOP (173), Tape/Reel

DS1305

DS1305E+T&R

0°C to +70°C

20 TSSOP (173 mils), Tape/Reel

DS1305

DS1305E

0°C to +70°C

20 TSSOP (173)

DS1305

DS1305EN

-40°C to +85°C

20 TSSOP (173 mils)

DS1305

DS1305EN/T&R

-40°C to +85°C

20 TSSOP (173 mils), Tape/Reel

DS1305

DS1305E/T&R

0°C to +70°C

20 TSSOP (173 mils), Tape/Reel

DS1305

DS1305N

-40°C to +85°C

16 DIP (300 mils)

DS1305N

+ Denotes a lead-free/RoHS-compliant device.

* An “N” on the top mark denotes an industrial device.

DESCRIPTION

The DS1305 serial alarm real-time clock provides a full binary coded decimal (BCD) clock calendar that

is accessed by a simple serial interface. The clock/calendar provides seconds, minutes, hours, day, date,

month, and year information. The end of the month date is automatically adjusted for months with fewer

than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour

format with AM/PM indicator. In addition, 96 bytes of NV RAM are provided for data storage. The

DS1305 will maintain the time and date, provided the oscillator is enabled, as long as at least one supply

is at a valid level.

that is compatible with the interface logic. This allows an easy interface to 3V logic in mixed supply

systems.

The DS1305 offers dual-power supplies as well as a battery input pin. The dual power supplies support a

programmable trickle charge circuit that allows a rechargeable energy source (such as a super cap or

a non-rechargeable battery. The DS1305 is fully operational from 2.0V to 5.5V.

Two programmable time-of-day alarms are provided by the DS1305. Each alarm can generate an

interrupt on a programmable combination of seconds, minutes, hours, and day. “Don’t care” states can be

inserted into one or more fields if it is desired for them to be ignored for the alarm condition. The time-of-

day alarms can be programmed to assert two different interrupt outputs or to assert one common interrupt

The DS1305 supports a direct interface to SPI serial data ports or standard 3-wire interface. A

straightforward address and data format is implemented in which data transfers can occur 1 byte at a time

or in multiple-byte-burst mode.