MAX31629MTA+T [MAXIM]
I2C Digital Thermometer and Real-Time Clock;
| 型号： | MAX31629MTA+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | I2C Digital Thermometer and Real-Time Clock |
| 文件： | 总21页 (文件大小：575K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
2
MAX31629
I C Digital Thermometer and Real-Time Clock
General Description
Benefits and Features
●ꢀ IntegrationꢀofꢀTemperatureꢀSensorꢀandꢀReal-Timeꢀ
2
The MAX31629 I C 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
TDFN package. Communication to the device is accom-
Clock Saves Space and Cost
• Measures Temperatures from -55°C to +125°C
(-67°F to +257°F)
• Real-Time Clock with Leap-Year Compensation
through the Year 2100
• 32 Bytes of SRAM for General Data Storage
• 8-Pin TDFN Package
2
plished through an I C interface. The wide power-supply
range and minimal power requirement of the device allow
for accurate time/temperature measurements in battery-
powered applications.
●ꢀ MinimalꢀPowerꢀRequirementsꢀꢀAllowꢀforꢀAccurateꢀ
Time/Temperature Measurements in Battery-Powered
Applications
The digital thermometer provides 9-bit to 12-bit tempera-
ture readings that indicate the temperature of the device.
No additional components are required; the device is truly
a “temperature-to-digital” converter.
• 2.2V to 5.5V Wide Power-Supply Range
●ꢀ User-ProgrammabilityꢀFlexiblyꢀSupportsꢀDifferentꢀ
Application Requirements
The clock/calendar provides seconds, minutes, hours,
day, day of the week, month, day of the 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 oscil-
lator 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.
• ThermometerꢀResolutionꢀisꢀUserꢀProgrammableꢀtoꢀ
9, 10, 11, or 12 Bits
• ThermostaticꢀandꢀTimeꢀAlarmꢀSettingsꢀareꢀUserꢀ
Definable
• Dedicated Open-Drain Alarm Output
●ꢀ Industry-StandardꢀSerialꢀInterfaceꢀWorksꢀwithꢀaꢀ
Variety of Common Microcontrollers
• Data is Read from/Written to through an I C Serial
2
The open-drain alarm output of the device becomes
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) generates an alarm condition. For stor-
age of general system data or time/temperature data
logging, the device features 32 bytes of SRAM.
Applications for the device include networking equipment,
industrial equipment, office equipment, thermal data
loggers, or any microprocessor-based, thermally sensitive
system.
Interface (Open-Drain I/O Lines)
●ꢀ Applications
●ꢀ NetworkingꢀEquipment
●ꢀ IndustrialꢀEquipment
●ꢀ OfficeꢀEquipment
●ꢀ DataꢀLoggersꢀandꢀAnyꢀThermallyꢀSensitiveꢀSystems
Ordering Information appears at end of data sheet.
For related parts and recommended products to use with this part, refer
to www.maximintegrated.com/MAX31629.related.
19-7305; Rev 1; 12/14
2
MAX31629
I C Digital Thermometer and Real-Time Clock
Absolute Maximum Ratings
Voltage Range on V
Relative to Ground .........-0.3V to +6.0V
Operating Temperature Range ........................ -55°C to +125°C
Storage Temperature Range............................ -55°C to +125°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow).......................................+260°C
DD
Voltage Range on Any Pin
Relative to Ground................................ -0.3V to (V + 0.3V)
ESDꢀProtectionꢀ(allꢀpins,ꢀHumanꢀBodyꢀModel)ꢀ ....................2kV
DD
Continuous Power Dissipation (T = +70°C)
A
TDFN (derate 24.4mW/°C above +70°C................1951.2mW
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 absolute maximum rating conditions for extended periods may affect
device reliability.
Package Thermal Characteristics
TDFN
(Note 1)
Junction-to-Ambient Thermal Resistance (B ).......... 41NC/W
JA
Junction-to-Case Thermal Resistance (B )................ 8NC/W
JC
Note 1:ꢀ PackageꢀthermalꢀresistancesꢀwereꢀobtainedꢀusingꢀtheꢀmethodꢀdescribedꢀinꢀJEDECꢀspecificationꢀJESD51-7,ꢀusingꢀaꢀfour-layerꢀ
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Recommended Operating Conditions
(T = -55°C to +125°C, unless otherwise noted.) (Note 2)
A
PARAMETER
Voltage Supply
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.5
UNITS
V
(Note 3)
(Note 3)
2.2
V
DD
0.3 x
Input Logic 0
Input Logic 1
V
-0.5
V
V
IL
V
DD
V
+
DD
V
(Note 3)
0.7V
DD
IH
0.5
Electrical Characteristics
(2.2Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = -55°C to +125°C, unless otherwise noted.)
DD
A
PARAMETER
Standby Current
SYMBOL
CONDITIONS
= 2.2V (Note 4)
MIN
TYP
MAX
0.1
UNITS
V
V
V
V
V
V
V
V
V
V
DD
DD
DD
DD
DD
DD
DD
DD
DD
DD
I
µA
DDS
= 5.0V (Note 4)
= 2.2V (Note 5)
= 5.0V (Note 5)
= 2.2V (Note 5)
= 5.0V (Note 5)
= 2.2V (Note 5)
= 5.0V (Note 5)
= 2.2V (Note 5)
= 5.0V (Note 5)
0.2
0.8
Timekeeping Current
I2C Communication
Thermometer Current
Active Current
I
I
µA
µA
µA
µA
DDC
1
100
150
1100
1100
1100
1200
I
DD2
DDT
I
DD
Logic 0 Output
(SDA, ALRM, OSC)
V
(Note 6)
0.4V < V < 0.9 V
0
0.4
V
OL
InputꢀCurrent,ꢀEachꢀI/OꢀPin
ThermometerꢀError
Resolution
-10
+10
±2
µA
I/O
DD
-10°C to +85°C, 2.7V < V
< 5.5V
DD
T
°C
ERR
4 sigma, 2.7V < V
< 5.5V
±3
DD
9
12
Bits
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MAX31629
I C Digital Thermometer and Real-Time Clock
Electrical Characteristics (continued)
(2.2Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = -55°C to +125°C, unless otherwise noted.)
DD
A
PARAMETER
SYMBOL
CONDITIONS
9 bits, 2.7V < V < 5.5V
MIN
TYP
MAX
25
UNITS
DD
10 bits, 2.7V < V
< 5.5V
< 5.5V
< 5.5V
50
DD
Conversion Time
t
ms
CONVT
11 bits, 2.7V < V
100
200
DD
12 bits, 2.7V < V
DD
Crystal Capacitance
C
(Note 7)
12.5
pF
C
ESR
50
kΩ
Nonvolatile Memory (EEPROM) Characteristics
((2.7Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = -55°C to +125°C, unless otherwise noted.)
DD
A
PARAMETER
EEPROMꢀWriteꢀCycleꢀTime
EEPROMꢀWrites
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ms
t
20
WR
N
-55°C to +55°C
-55°C to +55°C
50,000
10
Writes
Years
EEWR
t
EEDR
EEPROMꢀDataꢀRetention
2
I C AC Electrical Characteristics
(2.2Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = -55°C to +125°C, timing referenced to V
and V
, unless otherwise noted.) (Note 2) (Figure 1)
DD
A
IL(MAX)
IH(MAX)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Serial-Clock Frequency
f
400
kHz
CLK
Bus Free Time Between STOP
and START Condition
t
f
= 400kHz
CLK
1.3
0.6
µs
µs
BUF
Repeated START Condition
Setup Time
t
SU:STA
START Condition Setup Time
START Condition Hold Time
STOP Condition Setup Time
Clock Low Period
90% of SCL to 90% of SDA, f
90% of SDA to 90% of SCL, f
90% of SCL to 90% of SDA, f
10% to 10%
= 400kHz
0.6
0.6
0.6
1
µs
µs
µs
µs
µs
µs
CLK
CLK
CLK
t
= 400kHz
= 400kHz
HD:STA
t
SU:STO
t
LOW
Clock High Period
t
90% to 90%
1
HIGH
HD:DAT
Data-In Hold Time
t
(Note 9)
0
0.9
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MAX31629
I C Digital Thermometer and Real-Time Clock
2
I C AC Electrical Characteristics (continued)
(2.2Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = -55°C to +125°C, timing referenced to V
and V
, unless otherwise noted.) (Note 2) (Figure 1)
DD
A
IL(MAX)
IH(MAX)
PARAMETER
Data-In Setup Time
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ns
t
100
SU:DAT
Input Capacitance
C
5
pF
I
CapacitanceꢀLoadꢀforꢀEachꢀBusꢀ
Line
C
(Note 10)
300
pF
B
Note 2: Limits are 100% production tested at T = +25°C and/or T = +85°C. Limits over the operating temperature range and
A
A
relevant supply voltage range are guaranteed by design and characterization. Typical values are not guaranteed.
Note 3: All voltages referenced to ground.
Note 4: Standby current specified with temperature conversions and clock oscillator/buffer shut down, ALRM pin open, and SDA,
SCL = V , 0°C to +70°C.
DD
Note 5: I
specified with ALRM pin open, and 0°C to +70°C.
DD_
Note 6: Logic 0 voltage specified at a sink current of 4mA at V
= 5.0V and 1.5mA at V
= 2.2V.
DD
DD
Note 7:ꢀ ReferꢀtoꢀApplicationꢀNoteꢀ58:ꢀCrystal Considerations with Maxim Real-Time Clocks (RTCs).ꢀRecommndedꢀESRꢀ<ꢀ50kΩ.
Note 8: This delay applies only if the oscillator is running. If the oscillator is disabled or stopped, no power-up delay occurs.
Note 9: A master device must provide a hold time of at least 300ns for the SDA signal to bridge the undefined region of SCL’s
falling edge.
Note 10:
C is the total capacitance of one bus line in pF..
B
SDA
SCL
t
BUF
t
F
t
SP
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
t
R
HD:STA
t
SU:STO
t
t
SU:DAT
HD:DAT
STOP
START
REPEATED
START
NOTE: TIMING IS REFERENCED TO V
AND V
.
IL(MAX)
IH(MIN)
2
Figure 1. I C Timing
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MAX31629
I C Digital Thermometer and Real-Time Clock
Typical Operating Characteristics
(2.2Vꢀ≤ꢀV ꢀ≤ꢀ5.5V,ꢀT = +25°C, unless otherwise noted.)
DD
A
TIMEKEEPING CURRENT
vs. SUPPLY VOLTAGE
ACTIVE CURRENT
vs. SUPPLY VOLTAGE
toc01
toc02
1000
900
800
700
600
500
400
300
200
100
0
3
TA = +125°C
2.5
TA
TA
TA
=
+85°C
+25°C
TA = +125°C
=
2
=
-40°C
1.5
1
0.5
0
TA = +85°C
TA = +25°C
TA = -40°C
2
3
4
5
6
2
3
4
5
6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
TEMPERATURE MEASUREMENT
ERROR vs. TEMPERATURE
OSC FREQUENCY vs. TEMPERATURE
toc03
toc04
32.8
32.79
32.78
32.77
32.76
32.75
32.74
32.73
32.72
32.71
32.7
3
2
VCC = 3.3V
1
0
-1
-2
-3
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-55
-30
-5
20
45
70
95
120
TEMPERATURE (°C)
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MAX31629
I C Digital Thermometer and Real-Time Clock
Pin Configuration
TOP VIEW
V
OSC
7
X1
6
X2
5
DD
8
MAX31629
EP
4
+
1
2
3
SDA SCL ALRM GND
TDFN
Pin Description
PIN
NAME
FUNCTION
Serial-Data Input/Output. SDA is the input/output pin for the I2C serial interface. The SDA pin is an
open-drain output and requires an external pullup resistor. The pullup voltage can be up to 5.5V,
1
SDA
regardless of the voltage on V
.
DD
Serial-Clock Input. SCL is used to synchronize data movement on the I2C serial interface. The pullup
2
SCL
voltage can be up to 5.5V, regardless of the voltage on V
Thermostat and Clock Alarm Output
Ground
.
DD
3
4
ALRM
GND
Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for
5
X2
operationꢀwithꢀaꢀcrystalꢀhavingꢀaꢀspecifiedꢀloadꢀcapacitanceꢀ(C ) of 6pF. For more information about
L
crystal selection and crystal layout considerations, see the Applications Information section and refer
toꢀApplicationꢀNoteꢀ58:ꢀCrystal Considerations with Maxim Real-Time Clocks (RTCs).
6
7
X1
OSC
Buffered Oscillator Output
Primary Power Supply. When voltage is applied within normal limits, the device is fully accessible and
data can be written and read.
8
V
DD
EP
—
ExposedꢀPad.
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MAX31629
I C Digital Thermometer and Real-Time Clock
event, either thermal or time, or neither thermal or time
(disabled, power-up state). The thermal alarm becomes
Detailed Description
The factory-calibrated temperature sensor requires
no external components. The very first time that the
MAX31629 is powered up, it begins temperature conver-
sions and performs conversions continuously. The host
can periodically read the value in the temperature reg-
ister, which contains the last completed conversion. As
conversions are performed in the background, reading
the temperature register does not affect the conversion
in progress.
active when measured temperature is greater than or
equal to the value stored in the TH thermostat register. It
remains active until temperature is equal to or less than
the value stored in TL, allowing for programmable hyster-
esis. The clock alarm activates 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 device Configuration register defines several key
items of device functionality. It sets the conversion mode
of the digital thermometer and what event, if any, consti-
tutes 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 host can modify the device configuration such that
it does not power up in the autoconvert or continuous-
convert modes. This could be beneficial in power-
sensitive applications.
The real-time clock/calendar maintains a binary-coded
decimal (BCD) count of seconds, minutes, hours, day,
day of the week, month, day of the month, and year. It
does so with an internal oscillator/divider and a required
32.768kHz crystal. The end-of-the month date is automat-
ically updated for months with less than 31 days, includ-
ing compensation for leap years through the year 2100.
The clock format is configurable as a 12-hour (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 device 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 device through
2
an I C interface, and all communication is MSb first.
Individual registers are accessed by unique 8-bit
command protocols.
Theꢀdeviceꢀfeaturesꢀaꢀwideꢀpower-supplyꢀrangeꢀ(2.2Vꢀ≤ꢀ
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.
V
ꢀ≤ꢀꢀ5.5V)ꢀforꢀclockꢀfunctionality,ꢀSRAMꢀdataꢀretention,ꢀ
2
DD
and I Cꢀ communication.ꢀ EEPROMꢀ writesꢀ andꢀ tempera-
tureꢀconversionsꢀshouldꢀonlyꢀbeꢀperformedꢀatꢀ2.7Vꢀ≤ꢀV
≤ꢀ5.5Vꢀforꢀreliableꢀresults.
DD
The device features an open-drain alarm output that
can be configured to activate on a thermal event, time
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MAX31629
I C Digital Thermometer and Real-Time Clock
Block Diagram
2.2V TO 5.5V
SUPPLY
V
DD
DIRECT-TO-DIGITAL
MAX31629
TEMPERATURE SENSOR
THERMOMETER
REGISTER
THERMAL ALARM
COMPARATOR
SDA
SCL
TO
CPU
THERMAL ALARM
REGISTERS
R
P
ALRM
CONFIGURATION
REGISTER
2–WIRE
I/O CONTROL
AND
COMMAND
DECODING
SYSTEM
INTERRUPT
ALARM
SELECT
32 BYTES
USER SRAM
R
P
CLOCK ALARM
REGISTER
OSC
TO
CPU
CLOCK ALARM
COMPARATOR
CLOCK
REGISTER
X
X
1
DS1629
32.768kHz
CRYSTAL
OSCILLATOR
OSCILLATOR
DIVIDER AND
BUFFER
2
32.768kHz
CRYSTAL
GND
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 Configuration/Status Register
section.
Measuring Temperature
The device measures temperature using a bandgap-
based temperature sensor. A delta-sigma analog-to-digital
converter (ADC) converts the measured temperature to a
9-, 10-, 11-, or 12-bit (user-selectable) digital value that
is calibrated in °C; for °F applications, a lookup table or
conversion routine must be used. Throughout this data
sheet, the term “conversion” is used to refer to the entire
temperature measurement and ADC sequence.
The resolution of the output digital temperature data is
user-configurable or 9, 10, 11, or 12 bits, corresponding
to temperature increments of 0.5°C, 0.25°C, 0.125°C, and
0.0625°C, respectively. The default power-up is 12 bits
and can be changed through the R0 and R1 bits in the
Resolution register. Note that the conversion time doubles
for each bit of resolution.
The device can be configured to perform a single conver-
sion, store the result, and return to a standby mode, or it
can be programmed to convert continuously. The very first
time the device is powered up from the factory, it begins
temperature conversions and performs conversions
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MAX31629
I C Digital Thermometer and Real-Time Clock
After each conversion, the digital temperature sensor is
stored as a 16-bit two’s complement number in the two-
byte temperature register, as shown in Table 1. The sign
bit (S) indicates if the temperature is positive or negative;
for positive numbers, S = 0 and for negative numbers,
S = 1. The Read Temperature command [AAh] provides
userꢀ accessꢀ toꢀ theꢀ temperatureꢀ register.ꢀ Bitsꢀ 3:0ꢀ ofꢀ theꢀ
temperature register are hardwired to 0. When the device
isꢀconfiguredꢀforꢀ12-bitꢀresolution,ꢀtheꢀ12MSbsꢀ(bitsꢀ15:4)ꢀ
of the temperature register contain temperature data.
Forꢀ11-bitꢀresolution,ꢀtheꢀ11MSbsꢀ(bitsꢀ15:5)ꢀofꢀtheꢀtem-
perature register contain data, and bit 4 is 0. Likewise,
forꢀ10-bitꢀresolution,ꢀtheꢀ10MSbsꢀ(bitsꢀ15:6)ꢀcontainꢀdata,ꢀ
andꢀforꢀ9-bitꢀresolutionꢀtheꢀ9MSbsꢀ(bitsꢀ15:7)ꢀcontainꢀdata,ꢀ
and all unused LSbs contain 0s. Table 2 gives examples
of the 12-bit resolution output data and the correspond-
ing temperatures. The data is transmitted through the
1 to read the current time (read from the clock register).
See the I C Serial Data Bus section for details on this
protocol.
2
The format of the Clock register is shown in Table 3. Data
format for the Clock register is 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 does not
start (or stop) until the bus master issues a STOP pulse.
The device power-up default has the oscillator enabled
(CH = 0) so that OSC can be used for clocking a micro-
controller at power-up.
12 Mode/24 Mode = Clock Mode Bit. This bit is set high
when the clock is in the 12-hour mode and set to 0 in
the 24-hour 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.
2
I C serial interface, MSb first. The device can measure
temperature over the range of -55°C to +125°C in incre-
ments determined by the programmable bits of resolution
(see Table 1).
Real-Time Clock/Calendar
The device RTC/calendar data is accessed with the I C
command protocol, C0h. If the R/W bit in the I C control
byte is set to 0, then the bus master sets the clock (write
2
2
Bits in the Clock register filled with 0 are a “don’t care” on
a write, but always reads out as 0.
to the Clock register). The bus master sets the R/W bit to
Table 1. Temperature/Data Relationships
SIGN
2-1
26
25
24
23
0
22
0
21
0
20
0
MSB
LSB
2-2
2-3
2-4
(for 10-bit
conversions)
(for 11-bit
conversions)
(for 12-bit
conversions)
MSb
LSb
Table 2. Temperature Format Examples
TEMPERATURE (°C)
DIGITAL OUTPUT (BINARY)
0111 1101 0000 0000
0001 1001 0001 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
DIGITAL OUTPUT (HEX)
+125
+25.0625
+10.125
+0.5
7D00
1910
0A20
0080
0000
FF80
F5E0
E6F0
C900
0
-0.5
-10.125
-25.0625
-55
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MAX31629
I C Digital Thermometer and Real-Time Clock
Table 3. Clock Register Format
BYTE
ADDRESS
BIT 7
MSb
BIT 0
LSb
BYTE
RANGE
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
00h
01h
CH
0
10 Seconds
10 Minutes
AM/PM
Seconds
00-59
00-59
Minutes
Hours
12 Mode
01-12
00-23
02h
0
10 Hours
0
24 Mode
10 Hours
0
03h
04h
05h
06h
0
0
0
0
0
0
0
Day
01-07
01-31*
01-12
00-99
10 Date
Date
Month
Year
0
10 Month
10 Year
*Data byte maximum value ranges are from 28–31, depending on the month and year.
Alarms
The device features an open-drain alarm output with a
T
H
user-definable active state (factory default is active low).
By programming the Configuration register, the user also
defines the event, if any, that would generate an alarm
condition.ꢀTheꢀfourꢀpossibilitiesꢀare:
MEASURED
TEMPERATURE
T
L
TIME
CLOCK ALARM
SETTING
ASSUMES A
TIME READ
OCCURRED
1) Temperature alarm only.
CLOCK ALARM FLAG
1
0
2) Time alarm only.
CAF
FLAG
3)ꢀ Eitherꢀtemperatureꢀorꢀtimeꢀalarm.
4) Alarm disabled (power-up default).
TIME
See the Configuration/Status Register section for pro-
gramming 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 regis-
ter (TAF, CAF) that define the current state of each alarm.
In this way, the master can determine which event gener-
ated the alarm. If both events (thermal and time) are in
an alarm state, the ALRM output remains 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 2 illustrates a possible scenario with
this alarm mode. See the Thermometer Alarm and Clock
Alarm sections on how respective alarms are cleared.
THERMAL ALARM FLAG
1
0
TAF
FLAG
TIME
ALARM OUTPUT
ACTIVE
ALRM
OUTPUT
INACTIVE
TIME
THIS TRANSFER FUNCTION ASSUMES THE MAX31629 IS CONFIGURED SUCH
THAT EITHER A THERMAL OR TIME EVENT WILL GENERATE AN ALRM (A0 = A1 = 1).
Figure 2. Alarm Transfer Function
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MAX31629
I C Digital Thermometer and Real-Time Clock
Thermometer Alarm
Clock Alarm
The thermostat comparator updates as soon as a tem-
perature conversion is complete. When the device’s
temperature meets or exceeds the value stored in the
high temperature trip register (TH), the TAF flag becomes
active (high), and stays active until the temperature falls
below the temperature stored in the low-temperature
trigger register (TL).
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 remains active until the bus
master writes to or reads from either the Clock register
through the C0h command or the Clock Alarm register
through the C7h command.
2
The respective register can be accessed over the I C
bus through the Access TH (A1h) or Access TL (A2h)
commands. Reading from or writing to the respective
The format of the Clock Alarm register is shown in Table 5.
The power-up default of the device has the clock alarm
setꢀtoꢀ12:00AMꢀonꢀSunday.ꢀTheꢀregisterꢀcanꢀbeꢀaccessedꢀ
2
2
register is controlled by the state of the R/W bit in the I C
over the I C bus through the Access Clock Alarm (C7h)
2
control byte (see the I C Serial Data Bus section).
command. Reading from or writing to the register is con-
2
trolled by the state of the R/W bit in the I C control byte
The format of the TH and TL registers is identical to that
of the Thermometer register; that is, 9- to 12-bit two’s
complement representation of the temperature in °C. The
TH and TL resolution is determined by the R0 and R1 bits
in the Configuration register so the TH and TL resolution
matches the output temperature resolution. The TH and
TLꢀ registersꢀ areꢀ storedꢀ inꢀ EEPROM;ꢀ therefore,ꢀ theyꢀ areꢀ
NV and can be programmed prior to device installation.
Writing to and reading from the TH and TL registers is
achieved using the Access TH and Access TL commands.
When making changes to the TH and TL registers, con-
versions should first be stopped using the Stop Convert T
command if the device is in continuous-conversion mode.
Note that if the thermostat function is not used, the TH and
TL registers can be used as general-purpose NV memory.
2
(see the I C 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 always read out as a 0.
User SRAM
The device has memory reserved for any purpose the
user intends. The page is organized as 32 byte-wide
locations. The SRAM space is formatted as shown in
2
Table 6. It is accessed through the I C protocol, 17h. If the
R/W bit of the control byte is set to 1, the SRAM is 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.
Table 4. Thermostat Setpoint (TH/TL) Format in °C
SIGN
2-1
26
25
24
23
22
0
21
0
20
0
MSB
LSB
2-2
2-3
2-4
0
(for 10-bit
conversions)
(for 11-bit
conversions)
(for 12-bit
conversions)
MSb
LSb
Table 5. Clock Alarm Register Format
BYTE
ADDRESS
BIT 7
MSb
BIT 1
LSb
BYTE
RANGE
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
00h
01h
0
0
10 Seconds
10 Minutes
AM/PM
Seconds
Minutes
00–59
00–59
01–12
00–23
02h
03h
0
0
0
0
10 Hours
0
Hours
10 Hours
0
0
Day
01–07
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MAX31629
I C Digital Thermometer and Real-Time Clock
If the bus master is writing to/reading from the SRAM
array in the page mode (multiple byte mode), the address
pointer automatically wraps from address 1Fh to 00h
following the ACK after byte 1Fh.
CNV = Power-Up Conversion State: If CNV = 0 (factory
default), the device automatically initiates a temperature
conversion upon power-up and supply stability. Setting
CNV = 1 causes the device to power up in a standby
state. Table 8 illustrates how the user can set 1SH and
CNV, depending on the power consumption sensitivity of
the application.
The SRAM array does not have a defined power-up
default state. See the Command Set section for details of
the Access Memory protocol.
A0, A1 = Alarm Mode: Table 9 defines the device alarm
mode, based on the settings of the A0 and A1 bits. These
bits define what event activates the ALRM output. The
alarm flags (CAF, TAF, CAL, TAL) are functional regard-
less of the state of these bits. Both locations are read/
write and nonvolatile, and the factory-default state dis-
ables the ALRM output (A0 = A1 = 0).
Configuration/Status Register
The Configuration/Status register is accessed through the
Access Configuration (ACh) function command. Writing
to or reading from the register is determined by the R/W
2
2
bit of the I C control byte (see the I C Serial Data Bus
section). Data is read from or written to the Configuration
register MSb first. The format of the register is illustrated
in Table 7. The effect each bit has on device 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.
OS0, OS1 = Oscillator Output Setting: Table 10 defines
the frequency of the OSC output, as defined by the set-
tings 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.
1SH = Temperature Conversion Mode: If 1SHOT is 1,
the device performs one temperature conversion upon
reception of the Start Convert T protocol. If 1SHOT is
0, the device continuously performs temperature con-
versions and stores 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).
Table 6. SRAM Format
BYTE
00h
01h
02h
•••
CONTENTS
SRAM Byte 0
SRAM Byte 1
SRAM Byte 2
•••
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).
1Eh
1Fh
SRAM Byte 30
SRAM Byte 31
Table 7. Configuration/Status Register
EEPROM
OS1
CAF
MSb
OS0
TAF
A1
A0
0
0
CNV
POL
0
1SH
0
MSB
LSB
SRAM
CAL
TAL
0
LSb
Table 8. Thermometer Power-Up Modes
CNV
1SH
MODE
0
0
Powers up converting continuously (factory default).
Automatically performs one conversion upon power-up. Subsequent conversions require a
Start Convert T command.
0
1
1
1
0
1
Powers up in standby; upon Start Convert T command, conversions are performed continuously.
Powers up in standby; upon Start Convert T command, a single conversion is performed and stored.
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MAX31629
I C Digital Thermometer and Real-Time Clock
CAF = Clock Alarm Flag: This volatile status bit is set to
1 when the clock comparator is in an active state. Once
set, it remains at 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 read-only bit (writes to this location constitute a
“don’t care”) and the power-up default is the flag cleared
(CAF = 0).
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 is set
to 1 when the thermal comparator becomes active. Once
set, it remains latched until the device power is cycled.
A 0 in this location indicates the device 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).
TAF = Thermal Alarm Flag: This volatile status bit is set
to 1 when the thermal comparator is in an active state.
Once set, it remains at 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).
0 = Don’t Care: “Don’t care” on a write, but always reads
out as a 0.
Resolution Register
The Resolution register is accessed through the Access
Resolution (ADh) function command. Writing to or reading
2
from the register is determined by the R/W bit of the I C
2
control byte (see the I C Serial Data Bus section). Data
CAL = Clock Alarm Latch: This volatile status bit is set to
1 when the clock comparator becomes active. Once set, it
remains latched until the device power is cycled. A 0 in this
location indicates the clock has never been in an alarm
condition since the device was powered up. This is a read-
is read from or written to the Configuration register MSb
first. The format of the register is illustrated in Table 11.
The resolution selection is shown in Table 12. The default
value for the resolution is 12 bit. (R0 = R1 = 1).
Table 9. Alarm Mode Configuration
Table 10. OSC Frequency Configuration
A1
0
A0
0
ALARM MODE
Neither thermal or time (disabled)
Thermal only
OS1
OS0
OSC FREQUENCY
0
0
1
1
0
1
0
1
Disabled
0
1
1/8 f
0
0
1
0
Time only
1/4 f
1
1
Eitherꢀthermalꢀorꢀtime
f
0
Table 11. Resolution Register
BIT 7
0
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
R0
0
0
0
0
0
R1
MSb
LSb
Table 12. Resolution Configuration Settings
R1
0
R0
0
RESOLUTION (BITS)
TEMPERATURE RESOLUTION (°C)
9
0.5
0.25
0
1
10
11
1
0
0.125
0.0625
1
1
12 (default)
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MAX31629
I C Digital Thermometer and Real-Time Clock
A device that acknowledges must pull down the SDA line
during the acknowledge clock pulse in such a way that
2
I C Serial Data Bus
The device supports a bidirectional 2-wire bus and data-
transmission protocol. A device that sends data onto the
bus is defined as a transmitter and a device receiving the
data is defined 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 that generates the serial
clock (SCL), controls the bus access, and generates the
START and STOP conditions. The MAX31629 operates
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 3 details how data transfer is accom-
plished on the 2-wire bus.
2
as a slave on the I C bus. Connections to the bus are
Depending upon the state of the R/W bit, two types of
dataꢀtransferꢀareꢀpossible:
made through the open-drain I/O lines (SDA and SCL).
Theꢀfollowingꢀbusꢀprotocolꢀhasꢀbeenꢀdefined:
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.
●ꢀ Dataꢀ transferꢀ canꢀ beꢀ initiatedꢀ onlyꢀ whenꢀ theꢀ busꢀ is
not busy.
●ꢀ Duringꢀdataꢀtransfer,ꢀtheꢀdataꢀlineꢀmustꢀremainꢀstableꢀ
whenever the clock line is high. Changes in the data
line while the clock line is high are interpreted as
control signals.
2) Data Transfer from a Slave Transmitter to a Master
Receiver: The first byte (the slave address) is transmit-
ted by the master. The slave then returns an acknowl-
edge bit. Next follows a number of data bytes transmit-
ted 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” (NACK) 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 is not released.
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.ꢀEachꢀdataꢀtransferꢀisꢀinitiatedꢀwithꢀaꢀSTARTꢀcondi-
tion 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 device is 400kHz.
TheꢀMAX31629ꢀcanꢀoperateꢀinꢀtheꢀfollowingꢀtwoꢀmodes:
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 begin-
ning 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 indicates that the transfer
direction is reversed. Serial data is transmitted on SDA
by the device while the serial clock is input on SCL.
START and STOP conditions are recognized as the
beginning and end of a serial transfer.
Acknowledge: Eachꢀreceivingꢀdevice,ꢀwhenꢀaddressed,ꢀ
is obliged to generate an “acknowledge” (ACK) after the
reception of each byte. The master device must generate
an extra clock pulse that is associated with this acknowl-
edge bit.
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MAX31629
I C Digital Thermometer and Real-Time Clock
Slave Address
Command Set
Acontrol byte is the first byte received following the START
condition from the master device. The control byte has the
valueꢀofꢀ9Eh.ꢀThus,ꢀonlyꢀoneꢀMAX31629ꢀcanꢀresideꢀonꢀanꢀ
The command set for the MAX31629, as shown in
Tableꢀ13,ꢀisꢀasꢀfollows:
Access Configuration (ACh)
2
I C bus to avoid contention; however, as many as seven
If R/W is 0, this command writes to the Configuration/
Status register. After issuing this command, the next data
byte value is to be written into the Configuration/Status
register. If R/W is 1, the next data byte read is the value
stored in the Configuration/Status register. Because the
MSB of the Configuration/Status register is read/write and
the LSB is read-only, the user only needs to write 1 byte
toꢀtheꢀregister.ꢀEitherꢀ1ꢀorꢀ2ꢀbytesꢀcanꢀbeꢀread.
other devices with the 1001 control code can be dropped
on the I C bus so long as none contain the 111 address.
2
The last bit of the control byte (R/W) defines the opera-
tion to be performed. When set to a 1, a read operation
is selected; when set to a 0, a write operation is selected.
Following the START condition, the MAX31629 monitors
the SDA bus checking the device type identifier being
transmitted.ꢀ Uponꢀ receivingꢀ theꢀ controlꢀ byte,ꢀ theꢀ slaveꢀ
device outputs an ACK on the SDA line.
MAX31629 COMMUNICATION EXAMPLES
2
TYPICAL I C WRITE TRANSACTION
MSb
1
LSb
MSb
LSb
MSb
LSb
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
START
0
0
1
1
1
1
R/W
B7 B6 B5 B4 B3 B2 B1 B0
B7 B6 B5 B4 B3 B2 B1 B0
STOP
CONTROL BYTE
(SLAVE ADDRESS)
READ/
WRITE
COMMAND BYTE
DATA
2
EXAMPLE I C TRANSACTIONS
9Eh
ACh
C0h
A) SINGLE BYTE WRITE
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
1 0 0 1 1 1 1 0
1 0 1 0 1 1 0 0
1 1 0 0 0 0 0 0
STOP
-WRITE THE MSBYTE OF A START
TWO-BYTE REGISTER
(CONFIGURATION REGISTER)
TO C0H
9Eh
AAh
9Fh
B) SINGLE BYTE READ
-READ THE MSBYTE OF A
TWO-BYTE REGISTER
SLAVE
ACK
SLAVE REPEATED
SLAVE
ACK
MASTER
NACK
START 1 0 0 1 1 1 1 0
1 0 1 0 1 0 1 0
1 0 0 1 1 1 1 1
MSBYTE
STOP
ACK
START
READ
TEMPERATURE
(TEMPERATURE REGISTER)
9Eh
C0h
00h
00h
C) SINGLE BYTE WRITE TO AN
ADDRESSED REGISTER
-WRITE THE SECONDS
REGISTER OF THE CLOCK
TO A VALUE OF 00h
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
START 1 0 0 1 1 1 1 0
1 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
DATA
STOP
ACCESS
CLOCK
SECONDS
REGISTER
9Eh
A1h
55h
80h
D) TWO BYTE WRITE
-WRITE THE MSBYTE
AND LSBYTE OF THE TH
REGISTER TO 85.5°C
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
START 1 0 0 1 1 1 1 0
1 0 1 0 0 0 0 1
0 1 0 1 0 1 0 1
1 0 0 0 0 0 0 0
STOP
ACCESS
TH REGISTER
9Eh
AAh
9Fh
E) TWO BYTE READ
-READ THE MSBYTE
AND LSBYTE OF THE
TEMPERATURE
SLAVE
ACK
SLAVE REPEATED
SLAVE
ACK
MASTER
ACK
MASTER
NACK
START 1 0 0 1 1 1 1 0
1 0 1 0 1 0 1 0
1 0 0 1 1 1 1 1
MSBYTE
LSBYTE
ACK
START
READ
TEMPERATURE
9Eh
17h
F) MULTIPLE BYTE WRITE
-WRITE MULTIPLE BYTES
TO THE MEMORY REGITERS
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
START 1 0 0 1 1 1 1 0
0 0 0 1 0 1 1 1
ADDRESS
DATA
DATA
ACCESS MEMORY
STARTING BYTE
ADDRESS
SLAVE
ACK
SLAVE
ACK
DATA
DATA
STOP
9Eh
17h
9Fh
G) MULTIPLE BYTE READ
-READ MULTIPLE BYTES
FROM THE MEMORY
REGITERS
SLAVE
ACK
SLAVE
ACK
SLAVE REPEATED
SLAVE
ACK
MASTER
ACK
START 1 0 0 1 1 1 1 0
0 0 0 1 0 1 1 1
ADDRESS
1 0 0 1 1 1 1 1
DATA
ACK
START
ACCESS MEMORY
STARTING BYTE
ADDRESS
MASTER
ACK
MASTER
NACK
DATA
DATA
STOP
2
Figure 3. I C Serial Communication Examples
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MAX31629
I C Digital Thermometer and Real-Time Clock
Access Resolution (ADh)
Access Clock Alarm (C7h)
If R/W is 0, this command writes to the Resolution register.
After issuing this command, the next data byte value is to
be written into the Resolution register. If R/W is 1, the next
data byte read is the value stored in the Resolution register.
Accesses the device’s Clock Alarm register. If R/W is 0,
the master writes 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 write to or read from this register or the
Clock register is required to clear the clock alarm flag
(CAF). See Figure 3 for the protocol and Table 5 for the
Clock Alarm register map.
Start Convert T (EEh)
This command begins a temperature conversion. No
further data is required. In one-shot mode, the tempera-
ture conversion is performed and then the device remains
idle. In continuous mode, this command initiates continu-
ous conversions. Issuance of this protocol might not be
required upon device power-up, depending on the state
of the CNV bit in the Configuration register.
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
device, in the format described for thermostat set points,
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.
Stop Convert T (22h)
This command stops temperature conversion. No further
data is required. This command can be used to halt a
MAX31629 in continuous-conversion mode. After issuing
this command, the current temperature measurement
is completed, and the device remains idle until a Start
Convert T is issued to resume conversions.
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
device, in the format described for thermostat set points,
sets the low-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.
Read Temperature (AAh)
This command reads the last temperature conversion
result from the Thermometer register in the format
described in the Measuring Temperature section. If one’s
application can only accept thermometer resolution of
1.0°C, the master must only read the first data byte and
follow with a NACK and STOP. For higher resolution, both
bytes must be read.
Access Memory (17h)
This command instructs the device 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
I C control byte. The user can read/write all 32 bytes in
Access Clock (C0h)
succession within one command sequence, with the
pointer automatically incrementing. If the master attempts
to read/write more than 32 bytes, the address pointer
wraps to the 1st byte (00h) after the 32nd byte (1Fh) is
read/written and ACK’d by the master/slave. See Figure 3
for command protocol.
Accesses the device’s Clock/Calendar register. If R/W is
0, the master writes to the Clock register (sets 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 3
for the protocol and Table 3 for the Clock register map.
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MAX31629
I C Digital Thermometer and Real-Time Clock
Table 13. Command Set
DATA AFTER ISSUING
INSTRUCTION
PROTOCOL
DESCRIPTION
NOTES
PROTOCOL
CONFIGURATION/MEMORY COMMANDS
Writesꢀtoꢀ8-bitꢀConfigurationꢀregister
ReadsꢀfromꢀConfiguration/Statusꢀregisters
Writes to 8-bit Resolution register
Writes to SRAM array
1 data byte
AccessꢀConfiguration
Access Resolution
Access Memory
ACh
ADh
17h
11, 15
11, 15
11, 12
1 or 2 data bytes
1 data byte
Starting address + N - bytes
Starting address + N - bytes
Reads from SRAM array
THERMOMETER COMMANDS
Start Convert T
Stop Convert T
Read Temperature
EEh
Initiates temperature conversion(s)
Terminates continuous conversions
Reads Temperature register
Idle
13
13
14
22h
Idle
AAh
Read 1 or 2 data bytes
Write 2 data bytes or read 2
data bytes
Access TH
Access TL
A1h
A2h
Writes to/reads from TH register
Writes to/reads from TL register
11, 15
11, 15
Write 2 data bytes or read 2
data bytes
CLOCK COMMANDS
Access Clock
C0h
C7h
Sets/reads Clock registers
Starting address + N - bytes
Starting address + N - bytes
11, 12
11, 12
Access Clock Alarm
Sets/reads Clock Alarm registers
2
Note 11:Data direction depends on the R/W bit in the I C control byte.
Note 12:When accessing (reading from or writing to) addressed SRAM in the page mode, the address pointer automatically rolls
from the most significant byte to the least significant byte following the ACK of the most significant byte.
Note 13:In continuous-conversion mode, a Stop Convert T command halts 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.
Note 14: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.
Note 15:
WritingꢀtoꢀEEPROMꢀregistersꢀtypicallyꢀrequiresꢀ10msꢀatꢀroomꢀtemperatureꢀ(50msꢀmax).ꢀAfterꢀissuingꢀaꢀwriteꢀcommand,ꢀnoꢀ
furtherꢀwritesꢀshouldꢀbeꢀrequestedꢀforꢀ50ms.ꢀEEPROMꢀwritesꢀshouldꢀonlyꢀoccurꢀunderꢀtheꢀconditionsꢀ2.7Vꢀ≤ꢀV ꢀ≤ꢀ5.5Vꢀ
DD
andꢀ0°Cꢀ≤ꢀT ꢀ≤ꢀ70°C.
A
Sample Command Sequence No. 1
Sample Command Sequence No. 2
Example:ꢀ Theꢀ busꢀ masterꢀ configuresꢀ theꢀ deviceꢀ inꢀ theꢀ
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
toꢀ 11:30AMꢀ onꢀ Tuesday,ꢀ Januaryꢀ 1,ꢀ 2013.ꢀ Itꢀ setsꢀ theꢀ
thermostat with TH = 50°C. See Table 14.
Example:ꢀAssumingꢀtheꢀdeviceꢀisꢀconfiguredꢀsuchꢀthatꢀtheꢀ
clock is running and the thermometer is converting, read
the current time and temperature. Also read the status of
the alarm flags. See Table 15.
Maxim Integrated
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MAX31629
I C Digital Thermometer and Real-Time Clock
Table 14. Sample Command Sequence No. 1
BUS MASTER
MODE
DEVICE
MODE
DATA
(MSB FIRST)
COMMENTS
TX
TX
RX
TX
RX
TX
RX
TX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
RX
TX
RX
TX
RX
TX
RX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
RX
TX
RX
TX
RX
TX
RX
TX
RX
START
9Eh
Bus master initiates a START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
ACK
ACh
ACK
11h
Busꢀmasterꢀsendsꢀaccessꢀconfigurationꢀprotocol
Device generates acknowledge bit
Writeꢀtoꢀconfigurationꢀasꢀspecified
ACK
START
9Eh
Device generates acknowledge bit
Bus master initiates a repeated START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
ACK
C0h
ACK
00h
Bus master sends access clock protocol
Device generates acknowledge bit
Bus master sends starting clock register address
Device generates acknowledge bit
ACK
00h
Bus master sets seconds and enables the clock
Device generates acknowledge bit
ACK
30h
Bus master sets clock minutes
ACK
51h
Device generates acknowledge bit
Bus master sets clock hours and AM/PM clock mode
Device generates acknowledge bit
ACK
05h
Bus master sets day to Thursday
ACK
01h
Device generates acknowledge bit
Busꢀmasterꢀsetsꢀdateꢀtoꢀtheꢀfirstꢀofꢀtheꢀmonth
Device generates acknowledge bit
ACK
01h
Bus master sets month to January
ACK
98h
Device generates acknowledge bit
Bus master sets year to 1998
ACK
START
9Eh
Device generates acknowledge bit
Bus master initiates a repeated START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
Bus master sends access TH protocol
Device generates acknowledge bit
Bus master writes MSB of TH (50°C)
Device generates acknowledge bit
Bus master writes LSB of TH (50°C)
Device generates acknowledge bit
Bus master initiates STOP condition
ACK
A1h
ACK
32h
ACK
00h
ACK
STOP
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MAX31629
I C Digital Thermometer and Real-Time Clock
Table 15. Sample Command Sequence No. 2
BUS MASTER
MODE
DEVICE
MODE
DATA
(MSB FIRST)
COMMENTS
TX
TX
RX
TX
RX
TX
TX
RX
RX
TX
RX
TX
TX
TX
RX
TX
RX
TX
RX
TX
TX
RX
RX
TX
RX
TX
•
RX
RX
TX
RX
TX
RX
RX
TX
TX
RX
TX
RX
RX
RX
TX
RX
TX
RX
TX
RX
RX
TX
TX
RX
TX
RX
•
START
9Eh
Bus master initiates a START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
ACK
AAh
Bus master sends read temperature protocol
Device generates acknowledge bit
ACK
START
9Fh
Bus master initiates a Repeated START condition
Bus master sends device address; R/W = 1
Device generates acknowledge bit
ACK
<data byte>
ACK
Device generates MSB of temperature
Bus master generates acknowledge bit
Device generates LSB of temperature
Master generates no-acknowledge bit
Bus master initiates a repeated START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
<data byte>
NACK
START
9Eh
ACK
C0h
Bus master sends access clock protocol
Device generates acknowledge bit
ACK
01h
Bus master set clock register address to “minutes”
Device generates acknowledge bit
ACK
START
9Fh
Bus master initiates a Repeated START condition
Bus master sends device address; R/W = 1
Device generates acknowledge bit
ACK
<data byte>
ACK
Device generates minutes
Bus master generates acknowledge bit
Device generates hours and clock mode
Bus master generates acknowledge bit
•
<data byte>
ACK
•
RX
TX
TX
TX
RX
TX
RX
TX
RX
RX
TX
RX
TX
TX
TX
RX
RX
RX
TX
RX
TX
RX
TX
TX
RX
TX
RX
RX
<data byte>
NACK
START
9Eh
Device generates year
Master generates no-acknowledge bit
Bus master initiates a repeated START condition
Bus master sends device address; R/W = 0
Device generates acknowledge bit
ACK
ACh
Busꢀmasterꢀsendsꢀaccessꢀconfigurationꢀprotocol
Device generates acknowledge bit
ACK
9Fh
Bus master sends device address; R/W = 1
Device generates acknowledge bit
ACK
<data byte>
ACK
DeviceꢀgeneratesꢀMSBꢀofꢀConfigurationꢀregister
Master generates acknowledge bit
<data byte>
NACK
STOP
DeviceꢀgeneratesꢀLSBꢀofꢀConfigurationꢀregisterꢀ(flags)
Master generates no-acknowledge bit
Bus master initiates STOP condition
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MAX31629
I C Digital Thermometer and Real-Time Clock
Ordering Information
Package Information
For the latest package outline information and land patterns
PART
TEMP RANGE
PIN-PACKAGE
(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.
MAX31629MTA+
MAX31629MTA+T
-55°C to +125°C
-55°C to +125°C
8ꢀTDFN-EP*
8ꢀTDFN-EP*
+Denotes a lead (Pb)-free/RoHS-compliant package.
T = Tape and reel.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
*EP = Exposed pad.
8ꢀTDFN-EP
T833+2
21-0137
90-0059
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MAX31629
I C Digital Thermometer and Real-Time Clock
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
1
3/14
Initial release
UpdatedꢀBenefits and Features section
—
12/14
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
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 and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2014 Maxim Integrated Products, Inc.
│ 21
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