DS1305
ORDERING INFORMATION
PART
DS1305
DS1305N
DS1305E
DS1305E+
DS1305E/T&R
DS1305E+T&R
DS1305EN
DS1305EN+
DS1305EN/T&R
DS1305EN+T&R
TEMP RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 DIP (300 mils)
16 DIP (300 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
20 TSSOP (173 mils)
TOP MARK*
DS1305
DS1305N
DS1305
DS1305
DS1305
DS1305
DS1305
DS1305N
DS1305
DS1305
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
*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.
An interface logic power-supply input pin (V
CCIF
) allows the DS1305 to drive SDO and
PF
pins to a 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
rechargeable battery) to be used for a backup supply. The V
BAT
pin allows the device to be backed up by
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
output. Both interrupt outputs operate when the device is powered by V
CC1
, V
CC2
, or V
BAT
.
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.
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