DS1626/DS1726
High-Precision 3-Wire Digital
Thermometer and Thermostat
www.maxim-ic.com
DESCRIPTION
The
DS1626
and
DS1726
digital
thermometers/thermostats provide temperature
measurements and stand-alone thermostat
capability over a -55°C to +125°C range. The
DS1626 offers ±0.5°C accuracy from 0°C to
+70°C and the DS1726 has ±1°C accuracy from
-10°C to +85°C. The resolution of the measured
temperature is user selectable from 9 to 12 bits.
Communication with the DS1626 and DS1726 is
achieved through a 3-wire serial bus.
The DS1626 and DS1726 offer thermostatic
functionality with three dedicated thermostat
outputs (T
HIGH
, T
LOW
, and T
COM
), and
overtemperature (T
H
) and undertemperature (T
L
)
user-programmable thresholds stored in on-chip
EEPROM. For stand-alone thermostat operation,
T
H
and T
L
can be programmed prior to
installation, and the DS1626/DS1726 can be
configured to automatically begin taking
temperature measurements at power-up. Table 1
summarizes the user-accessible registers. Figure
1 shows a functional diagram.
FEATURES
Temperature Measurements Require No
External Components
Measure Temperatures from -55°C to
+125°C (-67°F to +257°F)
DS1626:
±0.5°C
Accuracy from 0°C to
+70°C
DS1726:
±1°C
Accuracy from -10°C to
+85°C
Output Resolution is User Selectable to 9,
10, 11, or 12 Bits
Wide Power-Supply Range (2.7V to 5.5V)
Convert Temperature to Digital Word in
750ms (max)
Stand-Alone Thermostat Capability
Thermostatic Settings are User Definable and
Nonvolatile (NV)
Data is Read/Written Through a 3-Wire
Serial Interface
Available in 8-Pin
μSOP
Package
PIN CONFIGURATION
TOP VIEW
APPLICATIONS
Thermostatic Controls
Industrial Controls
Consumer Products
Any Space-Constrained Thermally Sensitive
Application
DQ
CLK/CNV
RST
GND
1
2
3
4
8
DS1626
DS1726
7
6
5
V
DD
T
HIGH
T
LOW
T
COM
μSOP
PIN-PACKAGE
8
μSOP
8
μSOP
8
μSOP,
3000-Piece
8
μSOP,
3000-Piece
8
μSOP
8
μSOP
8
μSOP,
3000-Piece
8
μSOP,
3000-Piece
TOP MARK
1626
1626
1626
1626
1726
1726
1726
1726
ORDERING INFORMATION
PART
DS1626U
DS1626U+
DS1626U/T&R
DS1626U+T&R
DS1726U
DS1726U+
DS1726U/T&R
DS1726U+T&R
TEMP RANGE
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
+Denotes a lead-free package. A “+” symbol will also be marked on the package near the Pin 1 indicator.
T&R = Tape and reel.
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REV: 071107
DS1626/DS1726
PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
NAME
DQ
CLK/CNV
RST
GND
T
COM
T
LOW
T
HIGH
V
DD
FUNCTION
Data Input/Output Pin (Tri-State) for 3-Wire Serial Communication
Clock Input Pin for 3-Wire Serial Communication. Controls temperature
measurements when the DS1626/DS1726 is configured as a stand-alone thermostat.
Reset Input Pin for 3-Wire Serial Communication
Ground Pin
Thermostat Output Pin (Push-Pull) with Programmable Hysteresis
Thermostat Output Pin (Push-Pull) with T
L
Trip Point
Thermostat Output Pin (Push-Pull) with T
H
Trip Point
Supply Voltage. +2.7V to +5.5V input power pin.
MEMORY
TYPE
SRAM
EEPROM
REGISTER CONTENTS
AND POWER-UP/POR STATE
Measured Temperature (Two’s Complement)
Power-Up/POR State: -60ºC (1100 0100 0000)
Upper Alarm Trip Point (Two’s Complement)
Power-Up/POR State: User Defined
Initial State from Factory: +15°C (0000 1111 0000)
Lower Alarm Trip Point (Two’s Complement)
Power-Up/POR State: User Defined
Initial State from Factory: +10°C (0000 1010 0000)
Configuration and Status Information (Unsigned)
4MSbs = SRAM and 4LSbs = EEPROM
Power-Up/POR State: 1000XXXX (XXXX = User
Defined)
Table 1. DS1626/DS1726 REGISTER SUMMARY
REGISTER NAME
(USER ACCESS)
Temperature
(Read Only)
T
H
(Read/Write)
T
L
(Read/Write)
Configuration
(Various Bits are
Read/Write and Read
Only—See Table 3)
SIZE
12 Bits
12 Bits
12 Bits
EEPROM
1 Byte
SRAM and
EEPROM
Figure 1. DS1626/DS1726 FUNCTIONAL DIAGRAM
V
DD
GND
TEMPERATURE SENSOR AND
ΔΣ
ADC
ADDRESS
and
I/O CONTROL
CLK/CNV
SDA
RST
TEMPERATURE REGISTER
T
H
REGISTER
T
L
REGISTER
T
COM
T
HIGH
T
LOW
CONFIGURATION REGISTER AND CONTROL LOGIC
DIGITAL
COMPARATOR/LOGIC
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DS1626/DS1726
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground...................................................................-0.5V to +6.0V
Operating Temperature Range.............................................................................................-55°C to +125°C
Storage Temperature Range ................................................................................................-55°C to +125°C
Solder Dip Temperature (10s) .............................................................................................+260°C
Reflow Oven Temperature ..................................................................................................+220°C
These are stress ratings 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
reliability.
DC ELECTRICAL CHARACTERISTICS
(V
DD
= 2.7V to 5.5V, T
A
= -55°C to +125°C.)
PARAMETER
Supply Voltage
DS1626
Thermometer
Error
(Note 2)
DS1726
Thermometer
Error (Note 2)
Low-Level Input
Voltage
High-Level Input
Voltage
Input Current
each Input Pin
Active Supply
Current (Note 3)
SYMBOL
V
DD
CONDITIONS
(Note 1)
0°C to +70°C,
3.0V
≤
V
DD
≤
5.5V
0°C to +70°C,
2.7V
≤
V
DD
<
3.0V
-55°C to +125°C
-10°C to +85°C,
3.0V
≤
V
DD
≤
5.5V
-10°C to +85°C,
2.7V
≤
V
DD
<
3.0V
-55°C to +125°C
(Note 1)
(Note 1)
0.4 < V
I/O
< 0.9 x V
DD
Temperature conversion
-55°C to +85°C
Temperature conversion
+85°C to +125°C
E
2
write
RST
to GND
DQ, CLK to V
DD
0°C to +70°C (Note 3)
1mA source current
4mA sink current
(Note 4)
±0.2
2.4
0.4
V
°C
MIN
2.7
TYP
MAX
5.5
±0.5
±1.25
±2
±1
±1.5
±2
-0.5
0.7 x V
DD
-10
0.3 x V
DD
V
DD
+ 0.3
+10
1
mA
1.25
400
1
1.5
µA
MΩ
µA
V
V
µA
°C
°C
UNITS
V
T
ERR
T
ERR
V
IL
V
IH
I
DD
Input Resistance
Standby Supply
Current
THIGH, TLOW,
TCOM, DQ
Output Logic
Voltages (Note 1)
Thermal Drift
R
I
I
STBY
V
OH
V
OL
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DS1626/DS1726
EEPROM AC ELECTRICAL CHARACTERISTICS
(V
DD
= 2.7V to 5.5V, T
A
= -55°C to +125°C.)
PARAMETER
EEPROM Write Cycle Time
EEPROM Writes
EEPROM Data Retention
SYMBOL CONDITIONS
t
wr
N
EEWR
-55°C to +55°C
t
EEDR
-55°C to +55°C
MIN
50k
10
TYP
4
MAX
10
UNITS
ms
Writes
Years
AC ELECTRICAL CHARACTERISTICS
(V
DD
= 2.7V to 5.5V, T
A
= -55°C to +125°C.)
PARAMETER
Temperature Conversion Time
Data In to Clock Setup
Clock to Data In Hold
Clock to Data Out Delay
Clock Low/High Time
Clock Frequency
Clock Rise/Fall Time
RST
to Clock Setup
Clock to
RST
Hold
RST
Inactive Time
Clock High to I/O Hi-Z
RST
Low to I/O Hi-Z
CNV
Pulse Width
I/O Capacitance
Input Capacitance
SYMBOL
t
TC
t
DC
t
CDH
t
CDD
t
CL
, t
CH
f
CLK
t
R
, t
F
t
RC
t
CRH
t
RI
t
CDZ
t
RDZ
t
CNV
C
I/O
C
I
CONDITIONS
9 bits
10 bits
11 bits
12 bits
(Note 5)
(Note 5)
(Notes 5, 6)
(Note 5)
(Note 5)
(Note 5)
(Note 5)
(Note 5)
(Note 7)
(Note 5)
(Note 5)
(Note 8)
MIN
TYP
MAX
93.75
187.5
375
750
UNITS
ms
ns
ns
ns
ns
MHz
ns
ns
ns
ns
ns
ns
pF
pF
35
40
150
285
0
100
40
125
50
50
500ms
10
5
1.75
500
250ns
NOTES:
1)
2)
3)
4)
5)
6)
7)
8)
All voltages are referenced to ground.
See Figure 2 for
TYPICAL OPERATING CURVES.
I
STBY
, I
DD
specified with DQ, CLK/CNV = V
DD
and
RST
= GND.
Drift data is based on a 1000hr stress test at +125°C with V
DD
= 5.5V.
See Timing Diagrams in Figure 3. All timing is referenced to 0.7 x V
DD
and 0.3 x V
DD
.
Load capacitance = 50pF.
t
RI
must be 10ms minimum following any write command that involves the E
2
memory.
250ns is the guaranteed minimum pulse width for a conversion to start, however, a smaller pulse
width may start a conversion.
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DS1626/DS1726
Figure 2. TYPICAL OPERATING CURVES
DS1626
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-10
DS1726
ERROR (°C)
ERROR °C
+3σ
+3σ
MEAN
-3σ
10
20
30
40
50
60
70
MEAN
-3σ
0
10
20
30
40
50
60
70
80
REFERENCE TEMPERATURE (°C)
REFERENCE TEMPERATURE (°C)
Figure 3. TIMING DIAGRAMS
a) Read Timing
t
RC
t
CRH
b) Write Timing
t
RI
t
CRH
t
RC
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Embedded System
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