DS1629
2-Wire Digital Thermometer
and Real-Time Clock
FEATURES
Measures Temperatures from -55°C to
+125°C; Fahrenheit Equivalent is -67°F to
257°F
Real-Time Clock Counts Seconds, Minutes,
Hours, Date of the Month, Month, Day of the
Week, and Year with Leap Year
Compensation Through the Year 2100
Thermometer Accuracy is ±2.0°C (typ)
Thermometer Resolution is 9 Bits
(Expandable)
Thermostatic and Time Alarm Settings Are
User Definable; Dedicated Open-Drain Alarm
Output
32 Bytes SRAM for General Data Storage
Data is Read From/Written to via a 2-Wire
Serial Interface (Open Drain I/O Lines)
Wide Power Supply Range (2.2V to 5.5V)
Applications Include PCs/PDAs, Cellular
Telephones, Office Equipment, Data Loggers,
or Any Thermally Sensitive System
8-Pin (150-mil) SO Package
PIN CONFIGURATION
SDA
1
8
VDD
SCL
2
7
OSC
ALRM
3
X1
GND
4
6
5
X2
SO
(150 mils)
PIN DESCRIPTION
SDA
SCL
GND
ALRM
X1
X2
OSC
VDD
- 2-Wire Serial Data Input/Output
- 2-Wire Serial Clock
- Ground
- Thermostat and Clock Alarm
Output
- 32.768kHz Crystal Input
- 32.768kHz Crystal Feedback
Output
- Buffered Oscillator Output
- Power-Supply Voltage (+2.2V to
+5V)
DESCRIPTION
The DS1629 2-wire digital thermometer and real-time clock (RTC) integrates the critical functions of a
real-time clock and a temperature monitor in a small outline 8-pin SO package. Communication to the
DS1629 is accomplished via a 2-wire interface. The wide power-supply range and minimal power
requirement of the DS1629 allow for accurate time/temperature measurements in battery-powered
applications.
The digital thermometer provides 9-bit temperature readings which indicate the temperature of the device.
No additional components are required; the device is truly a “temperature-to-digital” converter.
The clock/calendar provides seconds, minutes, hours, day, date of the month, day of the week, month, and
year. The end of the month date is automatically adjusted for months with less than 31 days, including
corrections for leap years. It operates in either a 12- or 24-hour format with AM/PM indicator in 12-hour
mode. The crystal oscillator frequency is internally divided, as specified by device configuration. An
open-drain output is provided that can be used as the oscillator input for a microcontroller.
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19-6849; Rev 11/13
DS1629
The open-drain alarm output of the DS1629 will become active when either the measured temperature
exceeds the programmed overtemperature limit (TH) or current time reaches the programmed alarm
setting. The user can configure which event (time only, temperature only, either, or neither) will generate
an alarm condition. For storage of general system data or time/temperature data logging, the DS1629
features 32 bytes of SRAM. Applications for the DS1629 include personal computers/PDAs, cellular
telephones, office equipment, thermal data loggers, or any microprocessor-based, thermally-sensitive
system.
ORDERING INFORMATION
PART
DS1629S+
DS1629S+T&R
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
TOP MARK
DS1629
DS1629
PIN-PACKAGE
8 SO (150 mils)
8 SO (150 mils) (2500 piece)
DETAILED PIN DESCRIPTION Table 1
PIN
1
2
NAME
SDA
SCL
3
ALRM
4
5
6
7
8
GND
X2
X1
OSC
VDD
FUNCTION
Data Input/Output Pin for 2-Wire Serial Communication Port
Clock Input/Output Pin for 2-Wire Serial Communication Port
Alarm Output. Open drain time/temperature alarm output with configurable active
state.
Ground
32.768kHz Feedback Output
32.768kHz Crystal Input
Oscillator Output. Open-drain output used for microcontroller clock input.
Supply Voltage. 2.2V to 5.5V input power pin.
OVERVIEW
A block diagram of the DS1629 is shown in Figure 1. The DS1629 consists of six major components:
1.
Direct-to-digital temperature sensor
2.
Real-time clock
3.
2-wire interface
4.
Data registers
5.
Thermal and clock alarm comparators
6.
Oscillator divider and buffer
The factory-calibrated temperature sensor requires no external components. The very first time the
DS1629 is powered up it begins temperature conversions, and performs conversions continuously. The
host can periodically read the value in the temperature register, which contains the last completed
conversion. As conversions are performed in the background, reading the temperature register does not
affect the conversion in progress.
The host can modify DS1629 configuration such that it does not power up in the auto-convert or
continuous convert modes. This could be beneficial in power-sensitive applications.
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DS1629
The real-time clock/calendar maintains a BCD count of seconds, minutes, hours, day of the week, day of
the month, month, and year. It does so with an internal oscillator/ divider and a required 32.768kHz
crystal. The end of the month date is automatically updated for months with less than 31 days, including
compensation for leap years through the year 2100. The clock format is configurable as a 12- (power-up
default) or 24-hour format, with an AM/PM indicator in the 12-hour mode. The RTC can be shut down
by clearing a bit in the clock register.
The crystal frequency is internally divided by a factor that the user defines. The divided output is buffered
and can be used to clock a microcontroller.
The DS1629 features an open-drain alarm output. It can be configured to activate on a thermal event, time
event, either thermal or time, or neither thermal nor time (disabled, power-up state). The thermal alarm
becomes active when measured temperature is greater than or equal to the value stored in the TH
thermostat register. It will remain active until temperature is equal to or less than the value stored in TL,
allowing for programmable hysteresis. The clock alarm will activate at the specific minute of the week
that is programmed in the clock alarm register. The time alarm is cleared by reading from or writing to
either the clock register or the clock alarm register.
The DS1629 configuration register defines several key items of device functionality. It sets the
conversion mode of the digital thermometer and what event, if any, will constitute an alarm condition. It
also sets the active state of the alarm output. Finally, it enables/disables and sets the division factor for the
oscillator output.
The DS1629 also features 32 bytes of SRAM for storage of general information. This memory space has
no bearing on thermometer or chronograph operation. Possible uses for this memory are time/temperature
histogram storage, thermal data logging, etc.
Digital data is written to/read from the DS1629 via a 2-wire interface, and all communication is MSb
first. Individual registers are accessed by unique 8-bit command protocols.
The DS1629 features a wide power supply range (2.2V ≤ VDD ≤ 5.5V) for clock functionality, SRAM
data retention, and 2-wire communication. EEPROM writes and temperature conversions should only be
performed at 2.7V ≤ VDD ≤ 5.5V for reliable results.
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DS1629
BLOCK DIAGRAM Figure 1
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DS1629
OPERATION—MEASURING TEMPERATURE
The DS1629 measures temperature using a bandgap-based temperature sensor. A delta-sigma analog-todigital converter (ADC) converts the measured temperature to a digital value that is calibrated in °C; for
°F applications, a lookup table or conversion routine must be used. The device can be configured to
perform a single conversion, store the result, and return to a standby mode or it can be programmed to
convert continuously. The very first time the DS1629 is powered up from the factory, it begins
temperature conversions and performs conversions continuously. Regardless of the mode used, the last
completed digital temperature conversion is retrieved from the temperature register using the Read
Temperature (AAh) protocol, as described in detail in the Command Set section. Details on how to
change the settings after power-up are contained in the Operation—Configuration/Status Register
section.
The temperature reading is provided in a 9-bit, two’s complement format. Table 2 describes the exact
relationship of output data to measured temperature data. The data is transmitted through the 2-wire serial
interface, MSB first. The DS1629 can measure temperature over the range of -55°C to +125°C in 0.5°C
increments.
Note that temperature is represented in the DS1629 in terms of a 0.5°C LSB, yielding the 9-bit format
illustrated in Table 2. Higher resolutions may be obtained by reading the temperature and truncating the
0.5°C bit (the LSB) from the read value. This value is TEMP_READ. A Read Counter (A8h) command
should be issued to yield the 8-bit COUNT_REMAIN value. The Read Slope (A9h) command should
then be issued to obtain the 8-bit COUNT_PER_C value. The higher resolution temperature may then be
calculated by the user using the following equation:
T = TEMP_READ -0.25 +
(COUNT_PER_C - COUNT_REMAIN)
COUNT_PER_C
Temperature/Data Relationships Table 2
S
MSb
2-1
26
25
24
0
0
0
TEMPERATURE
+125°C
+25°C
0.5°C
0°C
-0.5°C
-25°C
-55°C
23
(unit = °C)
0
DIGITAL OUTPUT
(Binary)
01111101 00000000
00011001 00000000
00000000 10000000
00000000 00000000
11111111 10000000
11100111 00000000
11001001 00000000
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22
21
0
0
20
LSb
0
MSB
LSB
DIGITAL OUTPUT
(Hex)
7D00h
1900
0080
0000
FF80
E700h
C900h
DS1629
OPERATION—REAL-TIME CLOCK/CALENDAR
DS1629 real-time clock/calendar data is accessed with the 2-wire command protocol C0h. If the R/ W bit
in the 2-wire control byte is set to 0, the bus master will set the clock (write to the clock register). The bus
master sets the R/ W bit to 1 to read the current time (read from the clock register). See the 2-Wire Serial
Bus section for details on this protocol.
The format of the clock register is shown below in Figure 2. Data format for the clock register is binarycoded decimal (BCD). Most of the clock register is self-explanatory, but a few of the bits require
elaboration.
CH = Clock halt bit. This bit is set to 0 to enable the oscillator and set to 1 to disable it. If the bit is
changed during a write to the clock register, the oscillator will not be started (or stopped) until the bus
master issues a STOP pulse. The DS1629 power-up default has the oscillator enabled (CH = 0) so that
OSC can be used for clocking a microcontroller at power-up.
12/24 = Clock mode bit. This bit is set high when the clock is in the 12-hour mode and set to 0 in the 24hour mode. Bit 5 of byte 02h of the clock register contains the MSb of the hours (1 for hours 20-23) if the
clock is in the 24-hour mode. If the clock mode is set to the 12-hour mode, this is the AM/PM bit. In the
12-hour mode, a 0 in this location denotes AM and a 1 denotes PM. When setting the clock, this bit must
be written to according to the clock mode used.
Bits in the clock register filled with 0 are a don’t care on a write, but will always read out as 0.
DS1629 CLOCK REGISTER FORMAT Figure 2
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DS1629
OPERATION—ALARMS
The DS1629 features an open-drain alarm output with a user-definable active state (factory default is
active low). By programming the configuration register, the user also defines the event, if any, would
generate an alarm condition. The four possibilities are:
•
Temperature alarm only
•
Time alarm only
•
Either temperature or time alarm
•
Alarm disabled (power–up default)
See the Operation—Configuration/Status Register section for programming protocol.
If the user chooses the alarm mode under which a thermal or time event generates an alarm condition, it is
possible that either or both are generating the alarm. There are status bits in the configuration register
(TAF, CAF) that define the current state of each alarm. In this way, the master can determine which event
generated the alarm. If both events (thermal and time) are in an alarm state, the ALRM output will remain
active until both are cleared. ALRM is the logical OR of the TAF and CAF flags if the device is
configured for either to trigger the ALRM output. Figure 3 illustrates a possible scenario with this alarm
mode. See the Thermometer Alarm and Clock Alarm sections on how respective alarms are cleared.
DS1629 ALARM TRANSFER FUNCTION Figure 3
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DS1629
Thermometer Alarm
The thermostat comparator updates as soon as a temperature conversion is complete. When the DS1629’s
temperature meets or exceeds the value stored in the high temperature trip register (TH), the TAF flag
becomes active (high), and will stay active until the temperature falls below the temperature stored in the
low temperature trigger register (TL).
The respective register can be accessed over the 2-wire bus via the Access TH (A1h) or Access TL (A2h)
commands. Reading from or writing to the respective register is controlled by the state of the R/ W bit in
the 2-wire control byte (see the 2-Wire Serial Data Bus section).
The format of the TH and TL registers is identical to that of the Thermometer register; that is, 9-bit two’s
complement representation of the temperature in °C. Both TH and TL are nonvolatile EEPROM registers
guaranteed to 2K write cycles.
Thermostat Setpoint (TH/TL) Format Table 3
S
MSb
2-1
26
25
24
0
0
0
23
(unit = °C)
0
22
21
0
0
20
LSb
0
MSB
LSB
Clock Alarm
The clock alarm flag (CAF) becomes active within one second after the second, minute, hour, and day (of
the week) of the clock register match the respective bytes in the clock alarm register. CAF will remain
active until the bus master writes to or reads from either the clock register via the C0h command or the
clock alarm register via the C7h command.
The format of the clock alarm register is shown in Figure 4. The power-up default of the DS1629 has the
clock alarm set to 12:00AM on Sunday. The register can be accessed over the 2-wire bus via the Access
Clock Alarm (C7h) command. Reading from or writing to the register is controlled by the state of the
R/ W bit in the 2-wire control byte (see the 2-Wire Serial Data Bus section).
The master must take precaution in programming bit 5 of byte 02h to ensure that the alarm setting
matches the current clock mode. Bits designated with a 0 are a don’t care on writes, but will always read
out as a 0.
OPERATION—USER SRAM
The DS1629 has memory reserved for any purpose the user intends. The page is organized as 32 bytewide
locations. The SRAM space is formatted as shown in Table 4. It is accessed via the 2-wire protocol 17h.
If the R/ W bit of the control byte is set to 1, the SRAM will be read and a 0 in this location allows the
master to write to the array. Reads or writes can be performed in the single byte or page mode. As such,
the master must write the byte address of the first data location to be accessed.
If the bus master is writing to/reading from the SRAM array in the page mode (multiple byte mode), the
address pointer will automatically wrap from address 1Fh to 00h following the ACK after byte 1Fh.
The SRAM array does not have a defined power-up default state. See the Command Set section for details
of the Access Memory protocol.
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DS1629
SRAM FORMAT Table 4
BYTE
00h
01h
02h
...
1Eh
1Fh
CONTENTS
SRAM BYTE 0
SRAM BYTE 1
SRAM BYTE 2
...
SRAM BYTE 30
SRAM BYTE 31
CLOCK ALARM REGISTER FORMAT Figure 4
OPERATION—CONFIGURATION/STATUS REGISTER
The configuration/status register is accessed via the Access Config (ACh) function command. Writing to
or reading from the register is determined by the R/ W bit of the 2-wire control byte (see the 2-Wire
Serial Data Bus section). Data is read from or written to the configuration register MSb first. The format
of the register is illustrated in Figure 5. The effect each bit has on DS1629 functionality is described
along with the power-up state and volatility. The user has read/write access to the MSB and read-only
access to the LSB of the register.
Configuration/Status Register Figure 5
OS1
MSb
CAF
OS0
A1
A0
0
CNV
POL
TAF
CAL
TAL
0
0
0
1SH
LSb
0
MSB
LSB
1SH = Temperature Conversion Mode. If 1SHOT is 1, the DS1629 will perform one temperature
conversion upon reception of the Start Convert T protocol. If 1SHOT is 0, the DS1629 will continuously
perform temperature conversions and store the last completed result in the Thermometer Register. The
user has read/ write access to the nonvolatile bit, and the factory default state is 0 (continuous mode).
POL = ALRM Polarity Bit. If POL = 1, the active state of the ALRM output will be high. A 0 stored in
this location sets the thermostat output to an active-low state. The user has read/write access to the
nonvolatile POL bit, and the factory default state is 0 (active low).
CNV = Power-up conversion state. If CNV = 0 (factory default), the DS1629 will automatically initiate a
temperature conversion upon power-up and supply stability. Setting CNV = 1 causes the DS1629 to
power up in a standby state. Table 5 illustrates how the user can set 1SH and CNV, depending on the
power consumption sensitivity of the application.
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DS1629
Thermometer Power-Up Modes Table 5
CNV
0
ISH
0
0
1
1
0
1
1
MODE
Powers up converting continuously (factory default)
Automatically performs one conversion upon power-up. Subsequent conversions
require a Start Convert T command.
Powers up in standby; upon Start Convert T command, conversions will be performed
continuously.
Powers up in standby; upon Start Convert T command, a single conversion will be
performed and stored.
A0, A1 = Alarm Mode. Table 6 defines the DS1629 alarm mode, based on the settings of the A0 and A1
bits. These bits define what event will activate the ALRM output. The alarm flags—CAF, TAF, CAL,
TAL—are functional regardless of the state of these bits. Both locations are read/write and nonvolatile,
and the factory default state disables the ALRM output (A0 = A1 = 0).
Alarm Mode Configuration Table 6
A1
0
0
1
1
A0
0
1
0
1
ALARM MODE
Neither Thermal or Time (Disabled)
Thermal Only
Time Only
Either Thermal or Time
OS0, OS1 = Oscillator Output Setting. Table 7 defines the frequency of the OSC output, as defined by
the settings of these bits. Both locations are read/write and nonvolatile, and the factory default state sets
the OSC frequency equal to the crystal frequency (OS0 = OS1 = 1). The output should be disabled if the
user does not intend to use it to reduce power consumption.
OSC Frequency Configuration Table 7
OS1
0
0
1
1
OS0
0
1
0
1
OSC FREQUENCY
Disabled
1/8fO
1/4fO
fO
CAF = Clock Alarm Flag. This volatile status bit will be set to 1 when the clock comparator is in an
active state. Once set, it will remain 1 until reset by writing to or reading from either the clock register or
clock alarm register. A 0 in this location indicates the clock is not in an alarm condition. This is a readonly bit (writes to this location constitute a don’t care) and the power-up default is the flag cleared (CAF
= 0).
TAF = Thermal Alarm Flag. This volatile status bit will be set to 1 when the thermal comparator is in an
active state. Once set, it will remain 1 until measured temperature falls below the programmed TL setting.
A 0 in this location indicates the thermometer is not in an alarm condition. This is a read-only bit (writes
to this location constitute a don’t care) and the power-up default is the flag cleared (TAF = 0).
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DS1629
CAL = Clock Alarm Latch. This volatile status bit will be set to 1 when the clock comparator becomes
active. Once set, it will remain latched until DS1629 power is cycled. A 0 in this location indicates the
clock has never been in an alarm condition since the DS1629 was powered-up. This is a read-only bit
(writes to this location constitute a don’t care) and the power-up default is the flag cleared (CAL = 0).
TAL = Thermal Alarm Latch. This volatile status bit will be set to 1 when the thermal comparator
becomes active. Once set, it will remain latched until DS1629 power is cycled. A 0 in this location
indicates the DS1629 temperature has never exceeded TH since power-up. This is a read-only bit (writes
to this location constitute a don’t care) and the power-up default is the flag cleared (TAL = 0).
0 = Don’t care. Don’t care on a write, but will always read out as a 0.
2-WIRE SERIAL DATA BUS
The DS1629 supports a bidirectional two-wire bus and data transmission 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 “slaves.” The
bus must be controlled by a master device which generates the serial clock (SCL), controls the bus access,
and generates the START and STOP conditions. The DS1629 operates as a slave on the 2-wire bus.
Connections to the bus are made via the open-drain I/O lines SDA and SCL.
The following bus protocol has been defined:
•
Data transfer may 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 9th
bit.
The maximum clock rate of the DS1629 is 400kHz.
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DS1629
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.
Figure 6 details how data transfer is accomplished on the two-wire bus. 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.
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. Next follows a number of
data bytes transmitted by the slave to the master. 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 of 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.
The DS1629 may operate in the following two modes:
1.
Slave receiver 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. Address recognition is performed by hardware after
reception of the slave address and direction bit.
2.
Slave transmitter 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. Serial
data is transmitted on SDA by the DS1629 while the serial clock is input on SCL. START and
STOP conditions are recognized as the beginning and end of a serial transfer.
SLAVE ADDRESS
A control byte is the first byte received following the START condition from the master device. The
control byte consists of a 4-bit control code; for the DS1629, this is set as 1001 binary for read and write
operations. The next 3 bits of the control byte are the device select bits (A2, A1, A0). All 3 bits are hardwired high for the DS1629. Thus, only one DS1629 can reside on a 2-wire bus to avoid contention;
however, as many as seven other devices with the 1001 control code can be dropped on the 2-wire bus so
long as none contain the 111 address. The last bit of the control byte (R/ W ) defines the operation to be
performed. When set to a 1 a read operation is selected, and when set to a 0 a write operation is selected.
Following the START condition, the DS1629 monitors the SDA bus checking the device type identifier
being transmitted. Upon receiving the control byte, the slave device outputs an ACK on the SDA line.
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DS1629
2-WIRE SERIAL COMMUNICATION WITH DS1629 Figure 6
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DS1629
2-WIRE SERIAL COMMUNICATION WITH DS1629 Figure 6 (continued)
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DS1629
COMMAND SET
The DS1629 command set is shown below.
Access Config [ACh]
If R/ W is 0, this command writes to the configuration register. After issuing this command, the next data
byte value is to be written into the configuration register. If R/ W is 1, the next data byte read is the value
stored in the configuration register. Because the MSB of the configuration register is read/write and the
LSB is read-only, the user only needs to write one byte to the register. One or two bytes can be read.
Start Convert T [EEh]
This command begins a temperature conversion. No further data is required. In one-shot mode, the
temperature conversion will be performed and then the DS1629 will remain idle. In continuous mode, this
command will initiate continuous conversions. Issuance of this protocol may not be required upon
DS1629 power-up, depending upon the state of the CNV bit in the configuration register.
Stop Convert T [22h]
This command stops temperature conversion. No further data is required. This command may be used to
halt a DS1629 in continuous conversion mode. After issuing this command, the current temperature
measurement will be completed, and then the DS1629 will remain idle until a Start Convert T is issued to
resume conversions.
Read Temperature [AAh]
This command reads the last temperature conversion result from the Thermometer Register in the format
described in the Operation—Measuring Temperature section. If one’s application can accept
thermometer resolution of only 1.0°C, the master only must read the first data byte and follow with a
NACK and STOP. For higher resolution, both bytes must be read.
Read Counter [A8h]
This command returns the 8-bit COUNT_REMAIN value, used for high resolution thermometer
calculations.
Read Slope [A9h]
This command returns the 8-bit COUNT_PER_C value, used for high resolution thermometer
calculations.
Access Clock [C0h]
Accesses the DS1629 clock/calendar register. If R/ W is 0, the master will write to the clock register (set
the clock). If R/ W is 1, the clock register is read. The clock register is addressed, so the user must
provide a beginning byte address, whether a read or write is performed. A write to or read from this
register or the clock alarm register is required to clear the clock alarm flag (CAF). See Figure 6 for the
protocol and Figure 2 for the clock register map.
Access Clock Alarm [C7h]
Accesses the DS1629 clock alarm register. If R/ W is 0, the master will write to the clock alarm register
(set/ change the alarm). If R/ W is 1, the clock alarm register is read. The clock alarm register is
addressed, so the user must provide a beginning byte address, whether a read or write is performed. A
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DS1629
write to or read from this register or the clock register is required to clear the clock alarm flag (CAF). See
Figure 6 for the protocol and Figure 4 for the clock alarm register map.
Access TH [A1h]
If R/ W is 0, this command writes to the TH register. After issuing this command, the next two bytes
written to the DS1629, in the format described for thermostat set-points, will set the high temperature
threshold for operation of the ALRM output and TAF/TAL flags. If R/ W is 1, the value stored in this
register is read back.
Access TL [A2h]
If R/ W is 0, this command writes to the TL register. After issuing this command, the next two bytes
written to the DS1629, in the format described for thermostat set-points, will set the high temperature
threshold for operation of the ALRM output and TAF flag. If R/ W is 1, the value stored in this register is
read back.
Access Memory [17h]
This command instructs the DS1629 to access the user-SRAM array, starting with the specified byte
address. Read/write depends upon the state of the R/ W in the 2-wire control byte. The user can read/write
all 32 bytes in succession within one command sequence, with the pointer automatically wrapping from
1Fh to 00h; if the master attempts to read/write more than 32 bytes, the address pointer will wrap to the
first byte after the 32nd is read/written and ACKed by the master/slave. See Figure 6 for command
protocol.
16 of 23
DS1629
Command Set Table 8
2-WIRE BUS DATA
AFTER ISSUING
PROTOCOL
CONFIGURATION/MEMORY COMMANDS
Writes to 8-bit configuration
1 data byte
register
Reads from configuration/status
1 or 2 data bytes
register
Starting Address+NWrites to SRAM array
Bytes
Starting Address+NRead from SRAM array
Bytes
THERMOMETER COMMANDS
Initiates temperature
Idle
conversion(s)
Terminates continuous
Idle
conversions
INSTRUCTION
PROTOCOL
Access
Configuration
ACh
Access
Memory
17h
Start
Convert T
Stop
Convert T
Read
Temperature
Read Counter
Read Slope
EEh
22h
AAh
A8h
A9h
DESCRIPTION
Reads Temperature Register
Reads COUNT_REMAIN
Reads COUNT_PER_C
Writes to/Reads from TH
Register
Writes to/Reads from TL
Register
CLOCK COMMANDS
Access TH
A1h
Access TL
A2h
Access Clock
C0h
Sets/Reads Clock
Access Clock
Alarm
C7h
Sets/Reads Clock Alarm
NOTES:
1.
2.
3.
4.
5.
NOTES
1, 5
1, 2
3
3
Read 1 or 2 data bytes
4
Read 1 data byte
Read 1 data byte
Write 2 data bytes
Read 1 or 2 data bytes
Write 2 data bytes
Read 1 or 2 data bytes
1, 5
Starting Address + NBytes
Starting Address + NBytes
1, 5
1, 2
1, 2
Data direction depends upon R/ W bit in the 2-wire control byte.
When accessing (reading from or writing to) addressed SRAM in the page mode, the address
pointer will automatically roll from the most significant byte to the least significant byte following
the ACK of the most significant byte.
In continuous conversion mode, a Stop Convert T command will halt continuous conversion. To
restart, the Start Convert T command must be issued. In one-shot mode, a Start Convert T
command must be issued for every temperature reading desired.
If the user only desires 8-bit thermometer resolution, the master need only read 1 data byte, and
follow with a NACK and STOP. If higher resolution is required, 2 bytes must be read.
Writing to E2 registers typically requires 10ms at room temperature (50ms max). After issuing a
write command, no further writes should be requested for 50ms. E2 writes should only occur
under the conditions 2.7V ≤ VDD ≤ 5.5V and 0°C ≤ TJ ≤ 70°C.
17 of 23
DS1629
Sample Command Sequence Table 9
Example: The bus master configures the DS1629 in the power-up one-shot mode. It sets the ALRM
output active low with only the thermometer generating an ALRM and disables the oscillator output. It
then sets the clock to 11:30AM on Thursday, January 1, 1998. It sets the thermostat with TH = 50°C.
BUS MASTER DS1629
DATA (MSB
COMMENTS
MODE
MODE
FIRST)
TX
RX
START
Bus Master initiates a START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W = 0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
ACh
Bus Master sends access configuration protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
11h
Write to configuration as specified
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W =0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
C0h
Bus Master sends access clock protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
00h
Bus Master sends starting clock register address
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
00h
Bus Master sets seconds and enables the clock
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
30h
Bus Master sets clock minutes
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
51h
Bus Master sets clock hours and AM/PM clock mode
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
05h
Bus Master sets day to Thursday
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
01h
Bus Master sets date to the first of the month
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
01h
Bus Master sets month to January
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
98h
Bus Master sets year to ‘98
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W =0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
A1h
Bus Master sends access TH protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
32h
Bus Master writes MSB of TH (50°C)
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
00h
Bus Master writes LSB of TH (50°C)
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
STOP
Bus Master initiates STOP condition
18 of 23
DS1629
Sample Command Sequence Table 10
Example: Assuming the DS1629 is configured such that the clock is running and the thermometer is
converting, read the current time and temperature. Also read the status of the alarm flags.
BUS MASTER DS1629
DATA (MSB
COMMENTS
MODE
MODE
FIRST)
TX
RX
START
Bus Master initiates a START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W = 0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
AAh
Bus Master sends read temperature protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Fh
Bus Master sends DS1629 address; R/ W = 1
RX
TX
ACK
DS1629 generates acknowledge bit
RX
TX
DS1629 generates MSB of temperature
TX
RX
ACK
Bus Master generates acknowledge bit
RX
TX
DS1629 generates LSB of temperature
TX
RX
NACK
Master generates not-acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W = 0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
C0h
Bus Master sends access clock protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
01h
Bus Master set clock register address to “minutes”
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Fh
Bus Master sends DS1629 address; R/ W = 1
RX
TX
ACK
DS1629 generates acknowledge bit
RX
TX
DS1629 generates minutes
TX
RX
ACK
Bus Master generates acknowledge bit
RX
TX
DS1629 generates hours and clock mode
TX
RX
ACK
Bus Master generates acknowledge bit
•
•
•
•
RX
TX
DS1629 generates year
TX
RX
NACK
Master generates not-acknowledge bit
TX
RX
START
Bus Master initiates a repeated START condition
TX
RX
9Eh
Bus Master sends DS1629 address; R/ W = 0
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
ACh
Bus Master sends access configuration protocol
RX
TX
ACK
DS1629 generates acknowledge bit
TX
RX
9Fh
Bus Master sends DS1629 address; R/ W = 1
RX
TX
ACK
DS1629 generates acknowledge bit
RX
TX
DS1629 generates MSB of configuration register
TX
RX
ACK
Master generates acknowledge bit
RX
TX
DS1629 generates LSB of configuration register
(flags)
TX
RX
NACK
Master generates not-acknowledge bit
TX
RX
STOP
Bus Master initiates STOP condition
19 of 23
DS1629
ABSOLUTE MAXIMUM RATINGS
Voltage Range on VDD, Relative to Ground (Note 1)
Voltage Range on Any Other Pin, Relative to Ground
Continuous Power Dissipation (TA = +70°C)
SO (derate 7.80mW/°C above +70°C)
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering, 10s)
Soldering Temperature (reflow)
-0.3V to +6.0V
-0.3V to (VDD + 0.3V)
623.10mW
-55°C to +125°C
-55°C to +125°C
+300°C
+260°C
Note 1: All voltages are referenced to ground, unless otherwise noted.
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect device
reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 2)
SO
Junction-to-Ambient Thermal Resistance (θJA)
Junction-to-Case Thermal Resistance (θJC)
128.40°C/W
36°C/W
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification
JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
RECOMMENDED DC OPERATING CONDITIONS
(2.2V ≤ VDD ≤ 5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL CONDITION MIN
TYP
MAX
Supply Voltage
VDD
2.2
5.5
UNITS
V
NOTES
1, 11
UNITS
V
NOTES
DC ELECTRICAL CHARACTERISTICS
(2.2V ≤ VDD ≤ 5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL CONDITION MIN
TYP
MAX
Logic 0 Input
VIL
-0.5
0.3VDD
VDD +
Logic 1 Input
VIH
0.7VDD
0.5
Logic 0 Output (SDA,
VOL
0
0.4
ALRM, OSC)
Input Current
0.4 < VI/O <
-10
+10
Each I/O Pin
0.9VDD
VDD = 2.2V
0.1
Standby Current
IDDS
VDD = 5.0V
0.2
VDD = 2.2V
0.8
Timekeeping Current
IDDC
VDD = 5.0V
1
VDD = 2.2V
100
2-Wire
IDD2
Communication
VDD = 5.0V
150
VDD = 2.7V
1100
Thermometer Current
IDDT
VDD = 5.0V
1100
VDD = 2.7V
1100
Active Current
IDD
VDD = 5.0V
1200
20 of 23
V
V
3
µA
4
µA
5
µA
6
µA
6
µA
6
µA
6
DS1629
DC ELECTRICAL CHARACTERISTICS: DIGITAL THERMOMETER
(2.7V ≤ VDD ≤ 5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL CONDITION MIN TYP
MAX
-10°C to +85°C
DS1629 Thermometer
TERR
±2.0
2.7V ≤ VDD ≤
Error
5.5V
Resolution
0.062
0.5
Conversion Time
tCONVT
400
1000
UNITS
NOTES
°C
7
°C
ms
8
UNITS
µs
NOTES
AC ELECTRICAL CHARACTERISTICS: 2-WIRE INTERFACE
(2.2V ≤ VDD ≤ 5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL CONDITION MIN
TYP
MAX
SCL Clock Period
t1
2.5
Data In Setup Time to
t2
100
SCL High
Data Out Stable after
t3
0
SCL Low
SDA Low Setup Time
to SCL Low
t4
100
(START)
SDA High Hold Time
After SCL High
t5
100
(STOP)
Capacitance Load for
CB
400
Each Bus Line
Input Capacitance
CI
5
Crystal Capacitance
CC
12.5
ns
ns
ns
ns
pF
9
pF
pF
10
Note 3: Logic 0 voltage specified at a sink current of 4mA at VDD = 5.0V and 1.5mA at VDD = 2.2V.
Note 4: I/O pins of fast mode devices must not obstruct the SDA and SCL lines if VDD is switched off.
Note 5: Standby current specified with temperature conversions and clock oscillator/buffer shut down,
ALRM pin open, and SDA, SCL = VDD, 0°C to +70°C.
Note 6: IDDX specified with ALRM pin open, and 0°C to +70°C.
Note 7: See typical accuracy curve for specification limits outside the temperature range indicated.
Thermometer error is specified for 2.7V ≤ VDD ≤ 5.5V. Accuracy will degrade approximately 0.5°C if
ALRM is sinking the maximum current.
Note 8: Thermometer resolution (in °C) = 1/COUNT_PER_C(T). The calibration algorithm is such that
COUNT_PER_C and thus resolution varies over temperature (but is constant at a given temperature for a
given device) and from device to device.
Note 9: CB: Total capacitance of one bus line in pF.
Note 10: Refer to Application Note 58.
Note 11: Limits are 100% production tested at TA= +25°C and/or TA = +85°C. Limits over the operating
temperature range and relevant supply voltage are guaranteed by design and characterization.
21 of 23
DS1629
2-WIRE BUS TIMING DIAGRAM Figure 7
Typical DS1629 Thermometer Performance Curve Figure 9
PACKAGE INFORMATION
For
the
latest
package
outline
information
and
land
patterns
(footprints),
go
to
www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of
RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
8 SO
S8+5
21-0041
90-0096
22 of 23
DS1629
REVISION HISTORY
REVISION
DATE
11/13
DESCRIPTION
Updated the Ordering Information table; replaced the Operation—
Measuring Temperature section; updated the Absolute Maximum
Ratings section; added the Package Thermal Characteristics section;
changed the IDDC (2.2V max), IDD2 (5.0V max), IDDT (2.7V and 5.0V
max), and IDD (2.7V and 5.0V max) values in the DC Electrical
Characteristics table; changed the resolution parameter in the DC
Electrical Characteristics: Digital Thermometer table from 0.03°C(min)
to 0.062°C(min); added the Package Information section
PAGES
CHANGED
2, 5, 20, 21,
22
23 of 23
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2013 Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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