19-6264; Rev 0; 3/12
MAX31826
1-Wire Digital Temperature Sensor
with 1Kb Lockable EEPROM
General Description
The MAX31826 digital thermometer provides 12-bit
temperature measurements and communicates over a
1-Wire
M
bus that by definition requires only one data line
(and ground) for communication with a central microcon-
troller. It has a -55NC to +125NC operating temperature
range and is accurate to
Q0.5NC
over the -10NC to +85NC
range. In addition, the device can derive power directly
from the data line (“parasite power”), eliminating the
need for an external power supply.
Each device has a unique 64-bit serial code, which
allows multiple devices to function on the same 1-Wire
bus. Therefore, it is simple to use one microcontroller
(the master device) to control many devices distributed
over a large area. The device includes 128 bytes (1Kb)
of EEPROM for storage of system data. The EEPROM
can be locked to permanently prevent any further data
writes. Four location address inputs simplify mapping of
individual devices to specific locations.
Benefits and Features
S
Unique 1-Wire Interface Requires Only One Port
Pin for Communication
S
Integrated Temperature Sensor and EEPROM
Reduce Component Count
Measures Temperatures from -55NC to +125NC
(-67NF to +257NF)
±0.5NC Accuracy from -10NC to +85NC
12-Bit Temperature Resolution (0.0625NC)
1Kb EEPROM Can Be Locked to Prevent Further
Writes
S
Multidrop Capability Simplifies Multisensor
Systems
Each Device Has a Unique 64-Bit Serial Code
Stored in On-Board ROM
Four Pin-Programmable Bits to Uniquely
Identify Up to 16 Sensor Locations on a Bus
S
Can Be Powered from Data Line (3.0V to 3.7V
Power-Supply Range)
S
8-Pin µMAX
®
Package
Ordering Information
appears at end of data sheet.
For related parts and recommended products to use with this part,
refer to
www.maxim-ic.com/MAX31826.related.
Applications
Industrial Systems
Building Automation
Consumer Equipment
System Calibration
Module Identification
Block Diagram
V
PU
4.7kΩ
MEMORY
CONTROL LOGIC
PARASITE-
POWER
CIRCUIT
GND
C
PP
DQ
MAX31826
64-BIT ROM
AND
1-Wire PORT
1Kb
EEPROM
SCRATCHPAD 2
V
DD
POWER-
SUPPLY
SENSE
16-BIT TEMPERATURE REGISTER
SCRATCHPAD 1
8-BIT CRC GENERATOR
8-BIT CONFIGURATION REGISTER
ADDRESS PIN
INPUT LATCH
AD0 AD1 AD2 AD3
1-Wire and µMAX are registered trademarks of Maxim Integrated Products, Inc.
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Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX31826
1-Wire Digital Temperature Sensor
with 1Kb Lockable EEPROM
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground ....-0.5V to +4.5V
Continuous Power Dissipation (T
A
= +70NC)
FMAX
(derate 4.5mW/NC above +70NC) .....................362mW
Operating Temperature Range ........................ -55NC to +125NC
Storage Temperature Range............................ -55NC to +125NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
DC ELECTRICAL CHARACTERISTICS
(T
A
= -55°C to +125°C, unless otherwise noted.) (Note 1)
PARAMETER
Supply Voltage
Pullup Supply Voltage
(Notes 2, 3)
Thermometer Error (Note 4)
Input Logic-Low
SYMBOL
V
DD
V
PU
T
ERR
V
IL
CONDITIONS
Local power (Note 2)
Parasite power
Local power
-10NC to +85NC
-55NC to +125NC
(Notes 2, 5)
MIN
+3.0
+3.0
+3.0
-0.5
-2
-0.3
Q0.25
TYP
MAX
+3.7
+3.7
V
DD
+0.5
+2
+0.8
lower
of 3.7V
or
(V
DD
+
0.3V)
lower
of 3.7V
or
(V
DD
+
0.3V)
350
650
800
t
POR
Local or parasite power
-1
I
DQ
(Note 10)
5
4
1000
1200
1500
7.8
+1
UNITS
V
V
NC
V
Local power
Input Logic-High (Notes 2, 6)
V
IH
Parasite power
+2.4
V
+3.0
Sink Current
Standby Current
Active Current
Active Current with
Communication
POR Time
Input Leakage Current
(AD0–AD3 Pins)
DQ Input Current
I
L
I
DDS
I
DD
V
I/O
= 0.4V (Note 2)
(Notes 7, 8)
V
DD
= 3.7V (Note 9)
4.0
mA
nA
FA
FA
ms
FA
FA
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Maxim Integrated Products
2
MAX31826
1-Wire Digital Temperature Sensor
with 1Kb Lockable EEPROM
AC ELECTRICAL CHARACTERISTICS
(V
DD
= 3.0V to 3.7V, T
A
= -55°C to +125°C, unless otherwise noted.) (Note 1)
PARAMETER
Temperature Conversion Time
Time to Strong Pullup On
Time Slot
Recovery Time
Write-Zero Low Time
Write-One Low Time
Read Data Valid
Reset Time High
Reset Time Low
Presence-Detect High
Presence-Detect Low
DQ Capacitance
AD0–AD3 Capacitance
NONVOLATILE MEMORY
EEPROM Write/Erase Cycles
EEPROM Data Retention
EEPROM Write Time
N
EEWR
t
EEDR
t
WR
At T
A
= +25°C
At T
A
= +85°C (worst case)
At T
A
= +85°C (worst case)
200k
50k
40
20
25
Years
ms
SYMBOL
t
CONV
t
SPON
t
SLOT
t
REC
t
LOW0
t
LOW1
t
RDV
t
RSTH
t
RSTL
t
PDHIGH
t
PDLOW
C
IN/OUT
C
IN_AD
CONDITIONS
12-bit resolution
Start Convert T command, or Copy
Scratchpad 2 command issued
(Note 11)
(Note 11)
(Note 11)
(Note 11)
(Note 11)
(Note 11)
(Notes 11, 12)
(Note 11)
(Note 11)
480
480
15
60
60
240
25
50
60
1
60
1
120
15
15
MIN
TYP
MAX
150
10
120
UNITS
ms
Fs
Fs
Fs
Fs
Fs
Fs
Fs
Fs
Fs
Fs
pF
pF
Note 1:
Limits are 100% production tested at T
A
= +25°C and/or T
A
= +85°C. Limits over the operating temperature range and
relevant supply voltage range are guaranteed by design and characterization. Typical values are not guaranteed.
Note 2:
All voltages are referenced to ground.
Note 3:
The pullup supply voltage specification assumes that the pullup device is ideal, and therefore the high level of the pullup
is equal to V
PU
. To meet the device’s V
IH
specification, the actual supply rail for the strong pullup transistor must include
margin for the voltage drop across the transistor when it is turned on; thus: V
PU_ACTUAL
= V
PU_IDEAL
+ V
TRANSISTOR
.
Note 4:
Guaranteed by design. These limits represent a three sigma distribution.
Note 5:
To guarantee a presence pulse under low-voltage parasite-power conditions, V
ILMAX
might need to be reduced to as low
as 0.5V.
Note 6:
Logic-high voltages are specified at a 1mA source current.
Note 7:
Standby current specified up to T
A
= +70NC. Standby current typically is 3FA at T
A
= +125NC.
Note 8:
To minimize I
DDS
, DQ should be within the following ranges: V
GND
P
V
DQ
P
V
GND
+ 0.3V or V
DD
- 0.3V
P
V
DQ
P
V
DD
.
Note 9:
Active current refers to supply current during active temperature conversions or EEPROM writes.
Note 10:
DQ line is high (high-impedance state).
Note 11:
See the
1-Wire Timing Diagrams.
Note 12:
Under parasite power, if t
RSTL
> 960Fs, a power-on reset (POR) can occur.
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Maxim Integrated Products
3
MAX31826
1-Wire Digital Temperature Sensor
with 1Kb Lockable EEPROM
1-Wire Timing Diagrams
1-Wire WRITE-ZERO TIME SLOT
t
SLOT
t
REC
t
LOW0
START OF NEXT CYCLE
1-Wire READ-ZERO TIME SLOT
t
SLOT
t
REC
START OF NEXT CYCLE
t
RDV
1-Wire RESET PULSE
RESET PULSE FROM HOST
t
RSTL
t
RSTH
1-Wire PRESENCE DETECT
t
PDHIGH
PRESENCE DETECT
t
PDLOW
½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½½
Maxim Integrated Products
4
MAX31826
1-Wire Digital Temperature Sensor
with 1Kb Lockable EEPROM
Typical Operating Characteristics
(V
CC
= 3.3V, T
A
= -40°C, unless otherwise noted.)
MAX31826 TYPICAL ERROR CURVE
0.4
THERMOMETER ERROR (˚C)
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (˚C)
-3s ERROR
MEAN ERROR
+3s ERROR
MAX31826 toc01
0.5
Pin Configuration
PIN
TOP VIEW
V
DD
DQ
N.C.
GND
1
2
3
4
Pin Description
NAME
V
DD
FUNCTION
Optional V
DD
. V
DD
must be grounded for
operation in parasite-power mode.
Data Input/Output. Open-drain 1-Wire
interface pin. Also provides power to
the device when used in parasite-power
mode (see the
Parasite Power
section.)
No Connection. Not internally connected.
Ground
Location Address Input (Least Significant
Bit)
Location Address Input
Location Address Input
Location Address Input (Most Significant
Bit)
1
+
MAX31826
8
7
6
5
AD3
AD2
AD1
AD0
2
DQ
µMAX
3
4
5
6
7
8
N.C.
GND
AD0
AD1
AD2
AD3
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Maxim Integrated Products
5
Microchip MCU
