Maxim DS1307Z+TR 64 x 8, serial, i2c real-time clock Datasheet

DS1307
64 x 8, Serial, I C Real-Time Clock
2
GENERAL DESCRIPTION
FEATURES
The DS1307 serial real-time clock (RTC) is a lowpower, 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. The clock operates in either the 24-hour or 12hour 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.
TYPICAL OPERATING CIRCUIT
VCC
VCC
RPU
RPU
PIN CONFIGURATIONS
VCC
TOP VIEW
CRYSTAL
X1 X2
SCL
CPU
VCC
SQW/OUT
X1
VCC
X1
VCC
X2
SQW/OUT
X2
SQW/OUT
VBAT
SCL
VBAT
SCL
GND
SDA
GND
SDA
SO (150 mils)
DS130
SDA
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, General-Purpose RAM
with Unlimited Writes
I2C 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 Laboratories (UL) Recognized
PDIP (300 mils)
VBAT
GND
RPU = tr/Cb
ORDERING INFORMATION
PART
DS1307+
DS1307N+
DS1307Z+
DS1307ZN+
DS1307Z+T&R
DS1307ZN+T&R
TEMP RANGE
VOLTAGE (V)
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
5.0
5.0
5.0
5.0
5.0
5.0
PIN-PACKAGE
TOP MARK*
8 PDIP (300 mils)
8 PDIP (300 mils)
8 SO (150 mils)
8 SO (150 mils)
8 SO (150 mils) Tape and Reel
8 SO (150 mils) Tape and Reel
DS1307
DS1307N
DS1307
DS1307N
DS1307
DS1307N
+Denotes a lead-free/RoHS-compliant package.
*A “+” anywhere on the top mark indicates a lead-free package. An “N” anywhere on the top mark indicates an industrial temperature range
device.
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REV: 100208
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)…..……………………….Refer to the JPC/JEDEC J-STD-020 Specification.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED DC OPERATING CONDITIONS
(TA = 0°C to +70°C, TA = -40°C to +85°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.0
5.5
V
Supply Voltage
VCC
4.5
Logic 1 Input
VIH
2.2
VCC + 0.3
V
Logic 0 Input
VIL
-0.3
+0.8
V
VBAT
2.0
3
3.5
V
TYP
MAX
UNITS
VBAT Battery Voltage
DC ELECTRICAL CHARACTERISTICS
(VCC = 4.5V to 5.5V; TA = 0°C to +70°C, TA = -40°C to +85°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
Input Leakage (SCL)
ILI
-1
1
μA
I/O Leakage (SDA, SQW/OUT)
ILO
-1
1
μA
Logic 0 Output (IOL = 5mA)
VOL
0.4
V
Active Supply Current
(fSCL = 100kHz)
ICCA
1.5
mA
Standby Current
ICCS
200
μA
5
50
nA
1.25 x
VBAT
1.284 x
VBAT
V
TYP
MAX
UNITS
VBAT Leakage Current
Power-Fail Voltage (VBAT = 3.0V)
(Note 3)
IBATLKG
1.216 x
VBAT
VPF
DC ELECTRICAL CHARACTERISTICS
(VCC = 0V, VBAT = 3.0V; TA = 0°C to +70°C, TA = -40°C to +85°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
VBAT Current (OSC ON);
SQW/OUT OFF
IBAT1
300
500
nA
VBAT Current (OSC ON);
SQW/OUT ON (32kHz)
IBAT2
480
800
nA
VBAT Data-Retention Current
(Oscillator Off)
IBATDR
10
100
nA
WARNING: Negative undershoots below -0.3V while the part is in battery-backed mode may cause loss of data.
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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
SCL Clock Frequency
Bus Free Time Between a STOP and
START Condition
Hold Time (Repeated) START
Condition
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
100
kHz
fSCL
0
tBUF
4.7
μs
4.0
μs
tHD:STA
(Note 4)
LOW Period of SCL Clock
tLOW
4.7
μs
HIGH Period of SCL Clock
tHIGH
4.0
μs
Setup Time for a Repeated START
Condition
tSU:STA
4.7
μs
Data Hold Time
tHD:DAT
0
μs
Data Setup Time
tSU:DAT
250
ns
Rise Time of Both SDA and SCL
Signals
Fall Time of Both SDA and SCL
Signals
Setup Time for STOP Condition
(Notes 5, 6)
tR
1000
ns
tF
300
ns
tSU:STO
μs
4.7
CAPACITANCE
(TA = +25°C)
PARAMETER
SYMBOL
Pin Capacitance (SDA, SCL)
CI/O
Capacitance Load for Each Bus
Line
CB
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
CONDITIONS
(Note 7)
MIN
TYP
MAX
UNITS
10
pF
400
pF
Note 6:
All voltages are referenced to ground.
Limits at -40°C are guaranteed by design and are not production tested.
ICCS specified with VCC = 5.0V and SDA, SCL = 5.0V.
After this period, the first clock pulse is generated.
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the VIH(MIN) of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
The maximum tHD:DAT only has to be met if the device does not stretch the LOW period (tLOW) of the SCL signal.
Note 7:
CB—total capacitance of one bus line in pF.
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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
SQW/OUT
X1
CL
1Hz/4.096kHz/8.192kHz/32.768kHz
MUX/
BUFFER
1Hz
X2
CL
Oscillator
and divider
VCC
GND
POWER
CONTROL
CONTROL
LOGIC
VBAT
DS1307
SCL
SDA
SERIAL BUS
INTERFACE
AND ADDRESS
REGISTER
RAM
(56 X 8)
CLOCK,
CALENDAR,
AND CONTROL
REGISTERS
USER BUFFER
(7 BYTES)
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N
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
3.0
3.5
SQW/OUT vs. Supply Voltage
32768.5
SQW=32kHz
325.0
VBACKUP (V)
FREQUENCY (Hz)
SUPPLY CURRENT (nA)
32768.4
275.0
225.0
32768.3
32768.2
32768.1
SQW off
32768
2.0
175.0
-40
-20
0
20
40
60
2.5
3.0
3.5
4.0
Supply (V)
80
TEMPERATURE (°C)
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4.5
5.0
5.5
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.
Note: For more information on crystal selection and crystal layout considerations, refer to
Application Note 58: Crystal Considerations with Dallas Real-Time Clocks.
Backup Supply Input for Any Standard 3V Lithium Cell or Other Energy Source. Battery
voltage must be held between the minimum and maximum limits for proper operation.
Diodes in series between the battery and the VBAT pin may prevent proper operation. If a
backup supply is not required, VBAT must be grounded. The nominal power-fail trip point
(VPF) voltage at which access to the RTC and user RAM is denied is set by the internal
circuitry as 1.25 x VBAT nominal. A lithium battery with 48mAh or greater will back up the
DS1307 for more than 10 years in the absence of power at +25°C.
UL recognized to ensure against reverse charging current when used with a lithium
battery. Go to: www.maxim-ic.com/qa/info/ul/.
4
GND
5
SDA
6
SCL
7
SQW/OUT
8
VCC
Ground
Serial Data Input/Output. SDA is the data input/output for the I2C serial interface. The
SDA pin is open drain and requires an external pullup resistor. The pullup voltage can be
up to 5.5V regardless of the voltage on VCC.
Serial Clock Input. SCL is the clock input for the I2C interface and is used to synchronize
data movement on the serial interface. The pullup voltage can be up to 5.5V regardless of
the voltage on VCC.
Square Wave/Output Driver. When enabled, the SQWE bit set to 1, the SQW/OUT pin
outputs one of four square-wave frequencies (1Hz, 4kHz, 8kHz, 32kHz). The SQW/OUT
pin is open drain and requires an external pullup resistor. SQW/OUT operates with either
VCC or VBAT applied. The pullup voltage can be up to 5.5V regardless of the voltage on
VCC. If not used, this pin can be left floating.
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 connected to the
device and VCC is below VTP, read and writes are inhibited. However, the timekeeping
function continues unaffected by the lower input voltage.
DETAILED DESCRIPTION
The DS1307 is a low-power clock/calendar with 56 bytes of battery-backed SRAM. The clock/calendar provides
seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically
adjusted for months with fewer than 31 days, including corrections for leap year. The DS1307 operates as a slave
device on the I2C bus. Access is obtained by implementing a START condition and providing a device identification
code followed by a register address. Subsequent registers can be accessed sequentially until a STOP condition is
executed. When VCC falls below 1.25 x VBAT, the device terminates an access in progress and resets the device
address counter. Inputs to the device will not be recognized at this time to prevent erroneous data from being
written to the device from an out-of-tolerance system. When VCC falls below VBAT, the device switches into a lowcurrent battery-backup mode. Upon power-up, the device switches from battery to VCC when VCC is greater than
VBAT +0.2V and recognizes inputs when VCC is greater than 1.25 x VBAT. The block diagram in Figure 1 shows the
main elements of the serial RTC.
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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.
CLOCK ACCURACY
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match between
the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed. Additional
error will be added by crystal frequency drift caused by temperature shifts. External circuit noise coupled into the
oscillator circuit may result in the clock running fast. Refer to Application Note 58: Crystal Considerations with
Dallas Real-Time Clocks for detailed information.
Table 1. Crystal Specifications*
PARAMETER
Nominal Frequency
Series Resistance
Load Capacitance
SYMBOL
fO
ESR
CL
MIN
TYP
32.768
MAX
45
12.5
UNITS
kHz
kΩ
pF
*The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to
Application Note 58: Crystal Considerations for Dallas Real-Time Clocks for additional specifications.
Figure 2. Recommended Layout for Crystal
LOCAL GROUND PLANE (LAYER 2)
X1
CRYSTAL
X2
GND
NOTE: AVOID ROUTING SIGNAL LINES IN THE CROSSHATCHED
AREA (UPPER LEFT QUADRANT) OF THE PACKAGE UNLESS
THERE IS A GROUND PLANE BETWEEN THE SIGNAL LINE AND THE
DEVICE PACKAGE.
RTC AND RAM ADDRESS MAP
Table 2 shows the address map for the DS1307 RTC and RAM registers. The RTC registers are located in address
locations 00h to 07h. The RAM registers are located in address locations 08h to 3Fh. During a multibyte access,
when the address pointer reaches 3Fh, the end of RAM space, it wraps around to location 00h, the beginning of
the clock space.
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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., if 1 equals Sunday, then 2 equals
Monday, and so on.) Illogical time and date entries result in undefined operation. Bit 7 of Register 0 is the clock halt
(CH) bit. When this bit is set to 1, the oscillator is disabled. When cleared to 0, the oscillator is enabled. On first
application of power to the device the time and date registers are typically reset to 01/01/00 01 00:00:00
(MM/DD/YY DOW HH:MM:SS). The CH bit in the seconds register will be set to a 1. The clock can be halted
whenever the timekeeping functions are not required, which minimizes current (IBATDR).
The DS1307 can be run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the 12-hour or
24-hour mode-select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with
logic high being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20 to 23 hours). The hours value must be
re-entered whenever the 12/24-hour mode bit is changed.
When reading or writing the time and date registers, secondary (user) buffers are used to prevent errors when the
internal registers update. When reading the time and date registers, the user buffers are synchronized to the
internal registers on any I2C START. The time information is read from these secondary registers while the clock
continues to run. This eliminates the need to re-read the registers in case the internal registers update during a
read. The divider chain is reset whenever the seconds register is written. Write transfers occur on the I2C
acknowledge from the DS1307. Once the divider chain is reset, to avoid rollover issues, the remaining time and
date registers must be written within one second.
Table 2. Timekeeper Registers
ADDRESS
00h
01h
BIT 7
CH
0
02h
0
03h
04h
0
0
05h
0
06h
07h
OUT
BIT 6
BIT 5
BIT 4
10 Seconds
10 Minutes
10
12
10
Hour
Hour
PM/
24
AM
0
0
0
0
10 Date
10
0
0
Month
10 Year
0
0
SQWE
BIT 3
BIT 2
BIT 1
Seconds
Minutes
0
BIT 0
FUNCTION
Seconds
Minutes
RANGE
00–59
00–59
Hours
Hours
1–12
+AM/PM
00–23
DAY
Date
Day
Date
01–07
01–31
Month
01–12
Year
Control
RAM
56 x 8
00–99
—
Month
0
08h–3Fh
0 = Always reads back as 0.
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0
Year
RS1
RS0
00h–FFh
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 square-wave 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. On initial
application of power to the device, this bit is typically set to a 0.
Bit 4: Square-Wave Enable (SQWE). This bit, when set to logic 1, enables the oscillator output. The frequency of
the square-wave output depends upon the value of the RS0 and RS1 bits. With the square-wave output set to 1Hz,
the clock registers update on the falling edge of the square wave. On initial application of power to the device, this
bit is typically set to a 0.
Bits 1 and 0: Rate Select (RS[1:0]). These bits control the frequency of the square-wave output when the squarewave output has been enabled. The following table lists the square-wave frequencies that can be selected with the
RS bits. On initial application of power to the device, these bits are typically set to a 1.
RS1
0
0
1
1
X
X
RS0
0
1
0
1
X
X
SQW/OUT OUTPUT
1Hz
4.096kHz
8.192kHz
32.768kHz
0
1
9 of 14
SQWE
1
1
1
1
0
0
OUT
X
X
X
X
0
1
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. The DS1307
operates as a slave on the I2C bus.
Figures 3, 4, and 5 detail how data is transferred on the I2C bus.
Data transfer can be initiated only when the bus is not busy.
During data transfer, the data line must remain stable whenever the clock line is HIGH. Changes in the data
line while the clock line is high will be interpreted as control signals.
Accordingly, the following bus conditions have been defined:
Bus not busy: Both data and clock lines remain HIGH.
START data transfer: A change in the state of the data line, from HIGH to LOW, while the clock is HIGH,
defines a START condition.
STOP data transfer: A change in the state of the data line, from LOW to HIGH, while the clock line is HIGH,
defines the STOP condition.
Data valid: The state of the data line represents valid data when, after a START condition, the data line is
stable for the duration of the HIGH period of the clock signal. The data on the line must be changed during the
LOW period of the clock signal. There is one clock pulse per bit of data.
Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of
data bytes transferred between START and STOP conditions is not limited, and is determined by the master
device. The information is transferred byte-wise and each receiver acknowledges with a ninth bit. Within the
2
I C bus specifications a standard mode (100kHz clock rate) and a fast mode (400kHz clock rate) are defined.
The DS1307 operates in the standard mode (100kHz) only.
Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledge after the
reception of each byte. The master device must generate an extra clock pulse which is associated with this
acknowledge bit.
A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way
that the SDA line is stable LOW during the HIGH period of the acknowledge related clock pulse. Of course,
setup and hold times must be taken into account. A master must signal an end of data to the slave by not
generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave
must leave the data line HIGH to enable the master to generate the STOP condition.
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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
2
3-7
ACK
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. The first byte transmitted by the master is the
slave address. Next follows a number of data bytes. The slave returns an acknowledge bit after each received
byte. Data is transferred with the most significant bit (MSB) first.
2. Data transfer from a slave transmitter to a master receiver. The first byte (the slave address) is transmitted
by the master. The slave then returns an acknowledge bit. This is followed by the slave transmitting a number
of data bytes. The master returns an acknowledge bit after all received bytes other than the last byte. At the
end of the last received byte, a “not acknowledge” is returned.
The master device generates all the serial clock pulses and the START and STOP conditions. A transfer is
ended with a STOP condition or with a repeated START condition. Since a repeated START condition is also
the beginning of the next serial transfer, the bus will not be released. Data is transferred with the most
significant bit (MSB) first.
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DS1307 64 x 8, Serial, I2C Real-Time Clock
The DS1307 can 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). The slave address byte is the first byte received
after the master generates the START condition. The slave address byte contains the 7-bit DS1307
address, which is 1101000, followed by the direction bit (R/W), which for a write is 0. After receiving
and decoding the slave address byte, the DS1307 outputs an acknowledge on SDA. After the DS1307
acknowledges the slave address + write bit, the master transmits a word address to the DS1307. This
sets the register pointer on the DS1307, with the DS1307 acknowledging the transfer. The master can
then transmit zero or more bytes of data with the DS1307 acknowledging each byte received. The
register pointer automatically increments after each data byte are written. The master will generate a
STOP condition to terminate the data write.
2. Slave Transmitter Mode (Read Mode): The first byte is received and handled as in the slave receiver
mode. However, in this mode, the direction bit will indicate that the transfer direction is reversed. The
DS1307 transmits serial data on SDA while the serial clock is input on SCL. START and STOP
conditions are recognized as the beginning and end of a serial transfer (see Figure 5). The slave
address byte is the first byte received after the START condition is generated by the master. The slave
address byte contains the 7-bit DS1307 address, which is 1101000, followed by the direction bit (R/W),
which is 1 for a read. After receiving and decoding the slave address the DS1307 outputs an
acknowledge on SDA. The DS1307 then begins to transmit data starting with the register address
pointed to by the register pointer. If the register pointer is not written to before the initiation of a read
mode the first address that is read is the last one stored in the register pointer. The register pointer
automatically increments after each byte are read. The DS1307 must receive a Not Acknowledge to
end a read.
<Slave Address>
S
1101000
<RW>
Figure 4. Data Write—Slave Receiver Mode
0
<Word Address (n)>
A XXXXXXXX
<Data(n)>
A XXXXXXXX
<Data(n+1)>
A XXXXXXXX
<Data(n+X)>
A ... XXXXXXXX
A P
Master to slave
S - Start
A - Acknowledge (ACK)
P - Stop
DATA TRANSFERRED
(X+1 BYTES + ACKNOWLEDGE)
Slave to master
<Slave Address>
S
1101000
<RW>
Figure 5. Data Read—Slave Transmitter Mode
1
<Data(n)>
<Data(n+1)>
A XXXXXXXX
S - Start
A - Acknowledge (ACK)
P - Stop
A - Not Acknowledge (NACK)
A XXXXXXXX
Master to slave
Slave to master
<Data(n+2)>
A XXXXXXXX
<Data(n+X)>
A ... XXXXXXXX
A P
DATA TRANSFERRED
(X+1 BYTES + ACKNOWLEDGE); NOTE: LAST DATA BYTE IS
FOLLOWED BY A NOT ACKNOWLEDGE (A) SIGNAL)
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DS1307 64 x 8, Serial, I2C Real-Time Clock
<Slave Address>
S
1101000
0
<Word Address (n)>
A XXXXXXXX
<Data(n)>
XXXXXXXX
<Data(n+1)>
A XXXXXXXX
S - Start
Sr - Repeated Start
A - Acknowledge (ACK)
P - Stop
A - Not Acknowledge (NACK)
<Slave Address>
A Sr
1101000
<Data(n+2)>
Slave to master
1
A
<Data(n+X)>
A XXXXXXXX
Master to slave
<RW>
<RW>
Figure 6. Data Read (Write Pointer, Then Read)—Slave Receive and Transmit
A ... XXXXXXXX
A P
DATA TRANSFERRED
(X+1 BYTES + ACKNOWLEDGE); NOTE: LAST DATA BYTE IS
FOLLOWED BY A NOT ACKNOWLEDGE (A) SIGNAL)
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
8 PDIP
—
21-0043
8 SO
—
21-0041
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DS1307 64 x 8, Serial, I2C Real-Time Clock
REVISION HISTORY
REVISION
DATE
100208
Moved the Typical Operating Circuit and Pin Configurations to first page.
PAGES
CHANGED
1
Removed the leaded part numbers from the Ordering Information table.
1
Added an open-drain transistor to SQW/OUT in the block diagram (Figure 1).
Added the pullup voltage range for SDA, SCL, and SQW/OUT to the Pin
Description table and noted that SQW/OUT can be left open if not used.
Added default time and date values on first application of power to the Clock
and Calendar section and deleted the note that initial power-on state is not
defined.
Added default on initial application of power to bit info in the Control Register
section.
Updated the Package Information section to reflect new package outline
drawing numbers.
4
DESCRIPTION
6
8
9
13
14 of 14
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