The DS7505 low-voltage (1.7V to 3.7V) digital thermom-
eter and thermostat provides 9-, 10-, 11-, or 12-bit digital
temperature readings over a -55°C to +125°C range with
±0.5°C accuracy over a -0°C to +70°C range. A 9-bit reso-
lution mode is software compatible with the LM75.
The DS7505 thermostat has a dedicated open-drain
output (O.S.) and programmable fault tolerance, which
allows the user to define the number of consecutive error
conditions that must occur before O.S. is activated. There
are two thermostatic operating modes that control thermo-
stat operation based on user-defined trip points (T
OS
and
T
HYST
) that are stored in EEPROM registers.
Benefits and Features
●
Extends Performance Range with a Low-Voltage,
1.7V to 3.7V Operating Range
●
Maximizes System Accuracy in Broad Range of
Thermal Management Applications
• Measures Temperature from -55°C to +125°C
(-67°F to +257°F)
• ±0.5°C Accuracy Over a 0°C to +70°C Range
•
User-Configurable Resolution from 9 Bits (Default)
to 12 Bits (0.5°C to 0.0625°C Resolution)
●
Reduces Cost with No External Components and
Stand Alone Thermostat Capability
●
Increases Reliability and System Robustness
• Internally Filtered Data Lines for Noise Immunity
(50ns Deglitch)
• Bus Timeout Feature Prevents Lockup on a 2-Wire
Interface
●
Simplifies Distributed Temperature-Sensing
Applications with Multidrop Capability
• Up to Eight Devices Can Operate on a 2-Wire Bus
●
Fast 25ms (max) 9-Bit Conversion Time
●
Flexible and Nonvolatile (NV) User-Defined
Thermostatic Mode
s
Applications
●
●
●
●
●
Networking Equipment
Cellular Base Stations
Office Equipment
Medical Equipment
Any Thermally Sensitive System
Pin Configurations
TOP VIEW
SDA
SCL
O.S.
GND
1
2
3
4
8
VDD
A0
A1
A2
DS7505
7
6
5
Ordering Information
PART
DS7505S+
DS7505S+T&R
DS7505U+
TEMP RANGE
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
-55°C to +125°C
PIN-PACKAGE
8 SO (150 mils)
8 SO (150 mils),
2500-Piece T&R
8 µMAX®
8 µMAX,
3000-Piece T&R
SO
SDA
SCL
O.S.
GND
1
2
3
4
8
VDD
A0
A1
A2
DS7505
7
6
5
DS7505U+T&R
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
Commands are capitalized for clarity.
μMAX is a registered trademark of Maxim Integrated Products,
Inc.
µMAX
19-7471; Rev 3; 12/15
DS7505
Digital Thermometer and Thermostat
Absolute Maximum Ratings
Voltage Range on VDD Relative to Ground .........-0.3V to +4.0V
Voltage Range on Any Other Pin
Relative to Ground............................................-0.3V to +6.0V
Operating Temperature Range ......................... -55°C to +125°C
Storage Temperature Range ............................ -55°C to +125°C
Soldering Temperature ......................... Refer to the IPC/JEDEC
J-STD-020 Specification.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
DC Electrical Characteristics
(1.7V ≤ V
DD
≤ 3.7V, T
A
= -55°C to +125°C, unless otherwise noted.)
PARAMETER
Supply Voltage
Input Voltage Range (SDA, SCL,
O.S., A0, A1, A2)
Thermometer Error
(Note 2, 3)
Input Logic-High
Input Logic-Low
SDA Output Logic-Low Voltage
O.S. Saturation Voltage
Input Current Each I/O pin
I/O Capacitance
Standby Current
Active Current
(Notes 4, 5, 6)
C
I/O
I
DD1
I
DD
(Notes 4, 5, 6)
Active temp conversions
Communication only
E
2
Copy only
T
ERR
V
IH
V
IL
V
OL1
V
OL2
SYMBOL
V
DD
(Note 1)
0°C to +70°C
-55°C to +125°C
(Note 1)
(Note 1)
6mA sink current (Note 1)
4mA sink current (Notes 1, 2)
0.4V < V
I/O
< 0.9 x V
DD
-10
0
0.7 x V
DD
0.3 x V
DD
0.6
0.8
+10
10
2
750
100
500
µA
CONDITIONS
MIN
1.7
-0.3
MAX
3.7
+5.5
±0.5
±2.0
UNITS
V
V
°C
V
V
V
V
µA
pF
µA
AC Electrical Characteristics
(1.7V ≤ V
DD
≤ 3.7V, T
A
= -55°C to +125°C, unless otherwise noted.)
PARAMETER
Resolution
9-bit conversions
Temperature Conversion Time
t
CONVT
10-bit conversions
11-bit conversions
12-bit conversions
SCL Frequency
EEPROM Copy Time
EEPROM Copy Endurance
f
SCL
t
WR
N
EEWR
-40°C to +85°C
-40°C ≤ T
A
≤ +85°C (Note 7)
T
A
= +25°C (Note 7)
10k
40k
20k
80k
SYMBOL
CONDITIONS
MIN
9
TYP
MAX
12
25
50
100
200
400
10
kHz
ms
Cycles
ms
UNITS
Bits
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DS7505
Digital Thermometer and Thermostat
AC Electrical Characteristics (continued)
(1.7V ≤ V
DD
≤ 3.7V, T
A
= -55°C to +125°C, unless otherwise noted.)
PARAMETER
EEPROM Data Retention
Bus Free Time Between a STOP
and START Condition
START and Repeated START Hold
Time from Falling SCL
Low Period of SCL
High Period of SCL
Repeated START Condition Setup
Time to Rising SCL
Data-Out Hold Time from Falling
SCL
Data-In Setup Time to Rising SCL
Rise Time of SDA and SCL
(Receive)
Fall Time of SDA and SCL
(Receive)
Spike Suppression Filter Time
(Deglitch Filter)
STOP Setup Time to Rising SCL
Capacitive Load for Each Bus Line
Input Capacitance
Serial Interface Reset Time
Note 1:
Note 2:
SYMBOL
t
EEDR
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:DAT
t
SU:DAT
t
R
t
F
t
SS
t
SU:STO
C
B
C
I
t
TIMEOUT
SDA time low (Note 12)
75
5
325
(Note 9)
CONDITIONS
-40°C to +125°C (Note 8)
(Note 9)
(Notes 9, 10)
(Note 9)
(Note 9)
(Note 9)
(Notes 9, 11)
(Note 9)
(Notes 9, 12)
(Notes 9, 12)
0
600
400
MIN
10
1.3
600
1.3
0.6
600
0
100
1000
300
50
0.9
TYP
MAX
UNITS
Years
µs
ns
µs
µs
ns
µs
ns
ns
ns
ns
ns
pF
pF
ms
All voltages are referenced to ground.
Internal heating caused by O.S. loading causes the DS7505 to read approximately 0.5°C higher if O.S. is sinking the max-
rated current.
Note 3:
Specified in 12-bit conversion mode. Quantization error must be considered when converting in lower resolutions.
Note 4:
I
DD
specified with O.S. pin open.
Note 5:
I
DD
specified with V
DD
at 3.0V and SDA, SCL = 3.0V, T
A
= -55°C to +85°C.
Note 6:
I
DD
specified with A0, A1, A2 = 0V or V
DD
.
Note 7:
V
DD
must be > 2.0V.
Note 8:
E
2
Copy occurs at +25°C.
Note 9:
See the timing diagram (Figure 1). All timing is referenced to 0.9 x V
DD
and 0.1 x V
DD
.
Note 10:
After this period, the first clock pulse is generated.
Note 11:
The DS7505 provides an internal hold time of at least 75ns on the SDA signal to bridge the undefined region of SCL’s fall-
ing edge.
Note 12:
This timeout applies only when the DS7505 is holding SDA low. Other devices can hold SDA low indefinitely and the
DS7505 does not reset.
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DS7505
Digital Thermometer and Thermostat
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
SDA
SCL
O.S.
GND
A2
A1
A0
VDD
FUNCTION
Data Input/Output. For 2-wire serial communication port. Open drain.
Clock Input. For 2-wire serial communication port.
Thermostat Output. Open drain.
Ground
Address Input
Address Input
Address Input
Supply Voltage. +1.7V to +3.7V supply pin.
SDA
t
F
t
LOW
t
R
t
SU:DAT
t
F
t
HD:STA
t
SP
t
R
t
BUF
SCL
t
HD:STA
t
SU:STA
t
HD:DAT
SR
t
SU:STO
P
S
Figure 1. Timing Diagram
PRECISION
REFERENCE
VDD
SCL
SDA
A0
A1
A2
ADDRESS
AND
I/O CONTROL
OVERSAMPLING
MODULATOR
DIGITAL
DECIMATOR
CONFIGURATION
REGISTER
TEMPERATURE
REGISTER
T
OS
AND T
HYST
REGISTERS
THERMOSTAT
COMPARATOR
R
F
O.S.
GND
DS7505
Figure 2. Block Diagram
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DS7505
Digital Thermometer and Thermostat
Operation—Measuring Temperature
The DS7505 measures temperature using a bandgap
temperature-sensing architecture. An on-board delta-
sigma analog-to-digital converter (ADC) converts the
measured temperature to a digital value that is calibrated
in degrees Celsius; for Fahrenheit applications a lookup
table or conversion routine must be used. The DS7505 is
factory-calibrated and requires no external components to
measure temperature.
The DS7505 can be configured to power up either auto-
matically converting temperature or in a low-power standby
state. The preferred power-up mode can be set using the
SD bit in the configuration register as explained in the
Configuration Register
section. The resolution of the digital
output data is user-configurable to 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 factory default
resolution at power-up is 9 bits (R1 = 0, R0 = 0), however
this can be programmed to 10, 11, or 12 bits using the R0
and R1 bits in the configuration register as explained in the
Configuration Register
section. Note that the conversion
time doubles for each additional bit of resolution.
After each temperature measurement and analog-to-digital
(A/D) conversion, the DS7505 stores the temperature as a
16-bit two’s complement number in the 2-byte temperature
register (see Figure 3). The sign bit (S) indicates if the tem-
perature is positive or negative: for positive numbers S =
0 and for negative numbers S = 1. The most recently con-
verted digital measurement can be read from the tempera-
ture register at any time. Since temperature conversions
are performed in the background, reading the temperature
register does not affect the operation in progress.
Bits 3 through 0 of the temperature register are hardwired
to 0. When the DS7505 is configured for 12-bit resolution,
the 12 MSBs (bits 15 through 4) of the temperature reg-
ister contain temperature data. For 11-bit resolution, the
11 MSBs (bits 15 through 5) of the temperature register
contain data, and bit 4 reads out as 0. Likewise, for 10-bit
resolution, the 10 MSBs (bits 15 through 6) contain data,
and for 9-bit the 9 MSBs (bits 15 through 7) contain data
and all unused LSBs contains 0s. Table 1 gives examples
of 12-bit resolution digital output data and the correspond-
