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REV: 121906

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GENERAL DESCRIPTION

The DS1307 serial real-time clock (RTC) is a

low-power, full binary-coded decimal (BCD)

clock/calendar plus 56 bytes of NV SRAM.

Address and data are transferred serially through

an I

C, bidirectional bus. 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.

The DS1307 has a built-in power-sense circuit

that detects power failures and automatically

switches to the backup supply. Timekeeping

operation continues while the part operates from

the backup supply.

FEATURES

 Real-Time Clock (RTC) Counts Seconds,

Minutes, Hours, Date of the Month, Month,

Day of the week, and Year with Leap-Year

Compensation Valid Up to 2100

 56-Byte, Battery-Backed, Nonvolatile (NV)

RAM for Data Storage

 I

C Serial Interface

 Programmable Square-Wave Output Signal

 Automatic Power-Fail Detect and Switch

Circuitry

 Consumes Less than 500nA in Battery-

Backup Mode with Oscillator Running

 Optional Industrial Temperature Range:

-40°C to +85°C

 Available in 8-Pin Plastic DIP or SO

 Underwriters Laboratory (UL) Recognized

Typical Operating Circuit and Pin Configurations appear

at end of data sheet.

ORDERING INFORMATION

PART TEMP RANGE

VOLTAGE

(V)

PIN-PACKAGE TOP MARK*

DS1307 0°C to +70°C 5.0 8 PDIP (300 mils) DS1307

DS1307+ 0°C to +70°C 5.0 8 PDIP (300 mils) DS1307

DS1307N -40°C to +85°C 5.0 8 PDIP (300 mils) DS1307N

DS1307N+ -40°C to +85°C 5.0 8 PDIP (300 mils) DS1307N

DS1307Z 0°C to +70°C 5.0 8 SO (150 mils) DS1307

DS1307Z+ 0°C to +70°C 5.0 8 SO (150 mils) DS1307

DS1307ZN -40°C to +85°C 5.0 8 SO (150 mils) DS1307N

DS1307ZN+ -40°C to +85°C 5.0 8 SO (150 mils) DS1307N

DS1307Z/T&R 0°C to +70°C 5.0 8 SO (150 mils) Tape and Reel DS1307

DS1307Z+T&R 0°C to +70°C 5.0 8 SO (150 mils) Tape and Reel DS1307

DS1307ZN/T&R -40°C to +85°C 5.0 8 SO (150 mils) Tape and Reel DS1307N

DS1307ZN+T&R -40°C to +85°C 5.0 8 SO (150 mils) Tape and Reel DS1307N

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

* A “+” anywhere on the top mark indicates a lead-free device.

DS1307

64 x 8, Serial, I

C Real-Time Clock

Summary of content (15 pages)

PAGE 1
DS1307 64 x 8, Serial, I C Real-Time Clock 2 GENERAL DESCRIPTION FEATURES The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. 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.
PAGE 2
DS1307 64 x 8, Serial, I2C Real-Time Clock ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground……….……………………….…………....-0.5V to +7.0V Operating Temperature Range (Noncondensing) Commercial…………………….……………………………….………………………..0°C to +70°C Industrial………………………………………………………………………………-40°C to +85°C Storage Temperature Range………………………………………...…………..…………-55°C to +125°C Soldering Temperature (DIP, leads)..…………………………………………….....+260°C for 10 seconds Soldering Temperature (surface mount)…..
PAGE 3
DS1307 64 x 8, Serial, I2C Real-Time Clock AC ELECTRICAL CHARACTERISTICS (VCC = 4.5V to 5.5V; TA = 0°C to +70°C, TA = -40°C to +85°C.) PARAMETER SYMBOL SCL Clock Frequency Bus Free Time Between a STOP and START Condition Hold Time (Repeated) START Condition LOW Period of SCL Clock fSCL 0 tBUF 4.7 µs 4.0 µs tLOW 4.7 µs tHIGH 4.0 µs tHD:STA CONDITIONS (Note 4) MIN TYP MAX UNITS 100 kHz HIGH Period of SCL Clock Setup Time for a Repeated START Condition Data Hold Time tSU:STA 4.
PAGE 4
DS1307 64 x 8, Serial, I2C Real-Time Clock TIMING DIAGRAM SDA tBUF tLOW tR tHD:STA tF SCL tHD:STA STOP tSU:STA tHIGH START tSU:STO SU:DAT REPEATED START tHD:DAT Figure 1. Block Diagram X1 1Hz/4.096kHz/8.192kHz/32.
PAGE 5
DS1307 64 x 8, Serial, I2C Real-Time Clock TYPICAL OPERATING CHARACTERISTICS (VCC = 5.0V, TA = +25°C, unless otherwise noted.) ICCS vs. VCC IBAT vs. VBAT V BAT=3.0V V CC = 0V 400 120 SQW=32kHz 110 350 100 SUPPLY CURRENT (uA) SUPPLY CURRENT (nA) 90 300 80 70 250 60 50 SQW off 200 40 30 150 20 10 100 0 1.0 2.0 3.0 VCC (V) 4.0 IBAT vs. Temperature 2.0 5.0 2.5 V CC=0V, V BAT=3.0 VBACKUP (V) 3.0 3.5 SQW/OUT vs. Supply Voltage 32769 32768.9 SQW=32kHz 325.0 32768.
PAGE 6
DS1307 64 x 8, Serial, I2C Real-Time Clock PIN DESCRIPTION PIN NAME 1 X1 2 X2 3 VBAT FUNCTION Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for operation with a crystal having a specified load capacitance (CL) of 12.5pF. X1 is the input to the oscillator and can optionally be connected to an external 32.768kHz oscillator. The output of the internal oscillator, X2, is floated if an external oscillator is connected to X1.
PAGE 7
DS1307 64 x 8, Serial, I2C Real-Time Clock OSCILLATOR CIRCUIT The DS1307 uses an external 32.768kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. Table 1 specifies several crystal parameters for the external crystal. Figure 1. shows a functional schematic of the oscillator circuit. If using a crystal with the specified characteristics, the startup time is usually less than one second.
PAGE 8
DS1307 64 x 8, Serial, I2C Real-Time Clock CLOCK AND CALENDAR The time and calendar information is obtained by reading the appropriate register bytes. Table 2 shows the RTC registers. The time and calendar are set or initialized by writing the appropriate register bytes. The contents of the time and calendar registers are in the BCD format. The day-of-week register increments at midnight. Values that correspond to the day of week are user-defined but must be sequential (i.e.
PAGE 9
DS1307 64 x 8, Serial, I2C Real-Time Clock CONTROL REGISTER The DS1307 control register is used to control the operation of the SQW/OUT pin. BIT 7 OUT BIT 6 0 BIT 5 0 BIT 4 SQWE BIT 3 0 BIT 2 0 BIT 1 RS1 BIT 0 RS0 Bit 7: Output Control (OUT). This bit controls the output level of the SQW/OUT pin when the squarewave output is disabled. If SQWE = 0, the logic level on the SQW/OUT pin is 1 if OUT = 1 and is 0 if OUT = 0. Bit 4: Square-Wave Enable (SQWE).
PAGE 10
DS1307 64 x 8, Serial, I2C Real-Time Clock I2C DATA BUS The DS1307 supports the I2C protocol. A device that sends data onto the bus is defined as a transmitter and a device receiving data as a receiver. The device that controls the message is called a master. The devices that are controlled by the master are referred to as slaves. The bus must be controlled by a master device that generates the serial clock (SCL), controls the bus access, and generates the START and STOP conditions.
PAGE 11
DS1307 64 x 8, Serial, I2C Real-Time Clock Figure 3. Data Transfer on I2C Serial Bus SDA MSB R/W DIRECTION BIT ACKNOWLEDGEMENT SIGNAL FROM RECEIVER ACKNOWLEDGEMENT SIGNAL FROM RECEIVER SCL 1 START CONDITION 2 6 7 8 9 1 ACK 2 3-7 8 9 ACK REPEATED IF MORE BYTES ARE TRANSFERED STOP CONDITION OR REPEATED START CONDITION Depending upon the state of the R/W bit, two types of data transfer are possible: 1. Data transfer from a master transmitter to a slave receiver.
PAGE 12
DS1307 64 x 8, Serial, I2C Real-Time Clock The DS1307 may operate in the following two modes: 1. Slave Receiver Mode (Write Mode): Serial data and clock are received through SDA and SCL. After each byte is received an acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and end of a serial transfer. Hardware performs address recognition after reception of the slave address and direction bit (see Figure 4).
PAGE 13
DS1307 64 x 8, Serial, I2C Real-Time Clock S 1101000 0 A XXXXXXXX XXXXXXXX A Sr A XXXXXXXX S - Start Sr - Repeated Start A - Acknowledge (ACK) P - Stop A - Not Acknowledge (NACK) Figure 6. Data Read (Write Pointer, Then Read)—Slave Receive and Transmit 1 1101000 A XXXXXXXX Master to slave A A ...
PAGE 14
DS1307 64 x 8, Serial, I2C Real-Time Clock PACKAGE INFORMATION (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.
PAGE 15
DS1307 64 x 8, Serial, I2C Real-Time Clock PACKAGE INFORMATION (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) 15 of 15 Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product. No circuit patent licenses are implied.