MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
General Description
The MAX6625/MAX6626 combine a temperature sensor, a
programmable overtemperature alarm, and an I2C-compatible
serial interface into single compact packages. They convert
their die temperatures into digital values using internal analogto-digital converters (ADCs). The result of the conversion is
held in a temperature register, readable at any time through
the serial interface. A dedicated alarm output, OT, activates
if the conversion result exceeds the value programmed in
the high-temperature register. A programmable fault queue
sets the number of faults that must occur before the alarm
activates, preventing spurious alarms in noisy environments.
OT has programmable output polarity and operating modes.
The MAX6625/MAX6626 feature a shutdown mode that
saves power by turning off everything but the power-on
reset and the I2C-compatible interface. Four separate
addresses can be configured with the ADD pin, allowing
up to four MAX6625/MAX6626 devices to be placed on
the same bus. The MAX6625P/MAX6626P OT outputs
are open drain, and the MAX6625R/MAX6626R OT outputs
include internal pullup resistors.
The MAX6625 has a 9-bit internal ADC and can function
as a replacement for the LM75 in most applications. The
MAX6626 has a 12-bit internal ADC. Both devices come
in the space-saving 6-pin SOT23 package, or the 6-pin
TDFN package.
Applications
●●
●●
●●
●●
Fan Control
Temperature Alarms
System Temperature Control
Industrial Equipment
Features
●● 9-Bit Temperature-to-Digital Converter (MAX6625)
●● 12-Bit Temperature-to-Digital Converter (MAX6626)
●● I2C-Compatible Serial Interface
●● Up to Four Devices on a Single Bus
●● Versatile Alarm Output with Programmable Trip
Temperature and Hysteresis
●● Low-Power Shutdown Mode
●● Space-Saving TDFN or SOT23 Packages
●● Lead-Free Version Available (TDFN Package)
Ordering Information
PART
TEMP RANGE
-55°C to +125°C
6 SOT23
MAX6625RMUT*
-55°C to +125°C
6 SOT23
MAX6625PMTT*
-55°C to +125°C
6 TDFN-EP**
MAX6625RMTT*
-55°C to +125°C
6 TDFN-EP**
MAX6626PMUT*
-55°C to +125°C
6 SOT23
MAX6626RMUT*
-55°C to +125°C
6 SOT23
MAX6626PMTT*
-55°C to +125°C
6 TDFN-EP**
MAX6626RMTT*
-55°C to +125°C
6 TDFN-EP**
*For device options, see Selector Guide at end of data sheet.
Requires special solder temperature profile described in the
Absolute Maximum Ratings section.
**EP = Exposed pad.
# Indicates an RoHS-compliant part
Ordering Information is continued at end of data sheet.
Pin Configuration
Typical Operating Circuit
VS
TOP VIEW
+
SDA 1
GND 2
MAX6625
MAX6626
SCL 3
**EP = EXPOSED PAD
19-1841; Rev 7; 6/16
PIN-PACKAGE
MAX6625PMUT*
6
VS
5
ADD
0.1µF
4
4
SOT236
TDFN-EP**
1kΩ 1kΩ
6
MAX6625
MAX6626
OT
OT OUTPUT
1
3
5
2
10kΩ
(OMIT FOR MAX6625R
AND MAX6626R)
SDA
TO I2C
SCL MASTER
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Absolute Maximum Ratings
VS to GND................................................................-0.3V to +6V
OT, SCL, SDA to GND.............................................-0.3V to +6V
ADD to GND.................................................-0.3V to (VS + 0.3V)
Current into Any Pin............................................................±5mA
OT Sink Current..................................................................20mA
Continuous Power Dissipation
6-Pin SOT23 (derate 9.1mW/°C above +70°C)...........727mW
6-Pin TDFN (derate 23.8mW/°C above +70°C).........1905mW
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -60°C to +150°C
ESD Rating (Human Body Model).....................................2000V
Lead Temperature............................................................. Note 1
Note 1: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can
be exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recommended
in the industry-standard specification, IPC/JEDEC J-STD-020A, paragraph 7.6, Table 3 for IR/VPR and Convection Reflow.
Preheating is required. Hand or wave soldering is not allowed.
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.
Electrical Characteristics
(+3V ≤ VS ≤ +5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL
Power-Supply Voltage
CONDITIONS
VS
MIN
TYP
3.0
I2C-compatible active
Quiescent Current
IC
ADC Resolution
Temperature Resolution
I2C-compatible inactive
Power-Supply Sensitivity
5.5
V
1
mA
250
µA
1
µA
MAX6625
9
MAX6626
12
MAX6625
0.5
MAX6626
0.0625
Bits
°C/LSB
±1
0°C = TA ≤ +50°C, VS = +3.0V to +3.6V
±1.5
0°C = TA ≤ +70°C, VS = +3.0V to +3.6V
±2.0
VS = +3V to +5.5V
Conversion Time
tC
OT Pullup Resistor
RP
MAX6625R, MAX6626R only
OT Saturation Voltage (Note 4)
VL
IOUT = 4mA (Note 4)
OT Delay
UNITS
Shutdown mode
TA = +25°C, VS = +3V to +3.6V
Accuracy (Notes 2, 3)
MAX
(Programmable through fault queue)
°C
1
°C/V
133
ms
25
1 x tC
50
kΩ
0.8
V
6 x tC
ms
THIGH Default Temperature
THIGH
80
°C
TLOW Default Temperature
TLOW
75
°C
I2C-Compatible I/O: SCL, SDA, ADD
Input High Voltage
VIH
Input Low Voltage
VIL
Input Hysteresis
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VS < +3.6V
2
VS > +3.6V
3
V
0.8
0.2
V
V
Maxim Integrated │ 2
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Electrical Characteristics (continued)
(+3V ≤ VS ≤ +5.5V, TA = -55°C to +125°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input High Leakage Current
IIH
VIN = +5V
±1
µA
Input Low Leakage Current
IIL
VIN = 0
±1
µA
Input Capacitance
CIN
10
pF
Output Low Voltage
VOL
IOL = 3mA
0.4
V
Output High Current
IOH
VOH = 5V
1
µA
400
kHz
I2C-Compatible TIMING (Figure 1)
Serial Clock Frequency
fSCL
DC
Bus Free Time Between STOP
and START Conditions
tBUF
1.3
µs
START Condition Hold Time
tHD:STA
0.6
µs
STOP Condition Setup Time
tSU:STO
0.6
µs
Clock Low Period
tLOW
1.3
µs
Clock High Period
tHIGH
0.6
µs
Data Setup Time
tSU:DAT
Data Hold Time
tHD:DAT
(Note 5)
Maximum Receive SCL/SDA
Rise Time
tR
(Note 6)
300
ns
Minimum Receive SCL/SDA
Rise Time
tR
(Note 6)
20 +
0.1CB
ns
Maximum Receive SCL/SDA
Fall Time
tF
(Note 6)
300
ns
Minimum Receive SCL/SDA
Fall Time
tF
(Note 6)
20 +
0.1CB
ns
Transmit SDA Fall Time
tF
CB = 400pF, IO = 3mA (Note 6)
Pulse Width of Suppressed Spike
tSP
100
ns
0
0.9
20 +
0.1CB
(Note 7)
250
50
µs
ns
ns
Note 2: Guaranteed by design and characterization to ±5 sigma.
Note 3: Quantization error not included in specifications for temperature accuracy.
Note 4: Output current should be minimized for best temperature accuracy. Power dissipation within the MAX6625/MAX6626
causes self-heating and temperature drift; see the Thermal Considerations section.
Note 5: A master device must provide a hold time of at least 300ns for the SDA signal in order to bridge the undefined region of
SCL’s falling edge.
Note 6: CB = total capacitance of one bus line in pF. Tested with CB = 400pF.
Note 7: Input filters on SDA, SCL, and ADD suppress noise spikes less than 50ns.
SCL
tF
tHD:STA
tR
tLOW
tHIGH
tSU:DAT
tHD:DAT
tSU:STO
SDA
tBUF
Figure 1. Serial Bus Timing
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Maxim Integrated │ 3
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Typical Operating Characteristics
(VS = +3.3V, TA = +25°C, unless otherwise noted.)
STATIC QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
RESPONSE TO THERMAL SHOCK
TEMPERATURE vs. TIME
60
40
20
-5
0
5
10
15
MAX6625 toc02
140
120
80
20
-55
-25
5
35
65
TIME (s)
TEMPERATURE (°C)
DYNAMIC QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
TEMPERATURE ERROR
vs. TEMPERATURE
160
140
120
100
MAXIMUM LIMIT
3
-25
5
35
65
95
125
125
MAX6625 toc04
4
2
1
5 SIGMA RANGE
0
-1
-2
-3
MINIMUM LIMIT
-4
-55
95
5
TEMPERATURE ERROR (°C)
MAX6625 toc03
180
INPUT CURRENT (µA)
160
100
DEVICE IMMERSED IN +85°C
FLUORINERT BATH
200
80
180
INPUT CURRENT (µA)
80
0
200
MAX6625 toc01
OUTPUT TEMPERATURE (°C)
100
-5
-50
TEMPERATURE (°C)
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Pin Description
PIN
NAME
FUNCTION
1
SDA
I2C-Compatible Serial Bidirectional Data Line
2
GND
Power-Supply Ground
3
SCL
I2C-Compatible Clock Input
4
OT
Temperature Alarm Output
5
ADD
6
VS
Power-Supply Input, +3V to +5.5V. Bypass VS to GND with a 0.1µF capacitor.
—
EP
Exposed Paddle. Internally connected to GND. Connect to a large ground plane for maximum
thermal dissipation.
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I2C-Compatible Address Set Pin: Ground (0), VS (1), SDA (2), SCL (3); see Table 1.
Maxim Integrated │ 4
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Detailed Description
The MAX6625/MAX6626 continuously convert their die
temperatures into digital values using their self-contained
delta-sigma ADCs. The resulting data is readable at
any time through the I2C-compatible serial interface. A
dedicated alarm output asserts if the result exceeds the
value in the programmable high-temperature register. A
programmable fault queue sets the number of faults that
must occur before the alarm asserts, preventing spurious
alarms in noisy environments. The alarm output polarity is
selectable and deasserts based on either of two operating
modes, comparator or interrupt. In comparator mode, the
OT output deasserts if the temperature conversion result
falls below the programmable low-temperature register
value (subject to the fault queue conditions) providing
adjustable hysteresis. In interrupt mode, the OT output
deasserts when any register is read through the serial
interface. Each conversion cycle takes about 130ms. At
power-up, the temperature register is set to 8000h until
the first conversion is completed.
The MAX6625/MAX6626 feature a shutdown mode,
accessible through the serial interface, that saves power
by turning off everything but the power-on reset and the
I2C-compatible interface. While in shutdown mode, the
BANDGAP
REGISTER
REFERENCE
ADC
TEMP SIGNAL
temperature register is set to 8000h. The device functions as a slave on the I2C-compatible bus supporting
Write Byte, Write Word, Read Byte, and Read Word
commands. Four separate addresses can be configured
with the ADD pin, allowing up to four MAX6625/MAX6626
devices to be placed on the same bus. Figure 2 shows the
functional diagram of the MAX6625/MAX6626.
Serial interface
I2C-Compatible Operation
The MAX6625/MAX6626 are readable and programmable through their I2C-compatible serial interface. Figures 3
and 4 show the timing details of the clock (SCL) and data
(SDA) signals. The device functions as a slave on the
I2C-compatible bus and supports Write Byte, Write Word,
Read Byte, and Read Word commands.
Addressing
Four separate addresses can be configured with the ADD
pin, allowing up to four MAX6625/MAX6626s to be placed
on the same bus. The address is selected by connecting
the ADD pin to either of four places: GND (address 0), VS
(address 1), SDA (address 2), or SCL (address 3). Table
1 shows the full I2C-compatible address for each state.
MAX6625
MAX6626
+Vs
TEMPERATURE REGISTER
ADDRESS
POINTER
REGISTER
THIGH REGISTER
SET-POINT
COMPARATOR
MAX665_ R
ONLY
OT
TLOW REGISTER
CONFIGURATION REGISTER
SERIAL BUS INTERFACE
FAULT
QUEUE
COUNTER
GND
SDA
SCL
ADD
Figure 2. Functional Diagram
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Maxim Integrated │ 5
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START
BY
MASTER
START
BY
MASTER
START
BY
MASTER
ADDRESS
BYTE
ADDRESS
BYTE
ADDRESS
BYTE
POINTER
BYTE
ACK BY REPEAT
MAX6625 START
BY
MASTER
ADDRESS
BYTE
ACK BY
MAX6625
ACK BY
MAX6625
ACK BY
MAX6625
POINTER
BYTE
POINTER
BYTE
CONFIGURATION
BYTE
MOST-SIGNIFICANT
DATA BYTE
(c) THIGH AND TLOW WRITE
ACK BY
MAX6625
(b) CONFIGURATION REGISTER WRITE
ACK BY
MAX6625
ACK BY
MAX6625
MAX6625
DATA
BYTE
LEAST-SIGNIFICANT
DATA BYTE
STOP
COND BY
ACK BY MASTER
(a) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FROM CONFIGURATION REGISTER
ACK BY
MAX6625
ACK BY
MAX6625
STOP
COND BY
MASTER
NO
ACK BY
MASTER
STOP
COND BY
MASTER
MAX6625/MAX6626
I2C-Compatible
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
Figure 3. I2C-Compatible Timing Diagram
Maxim Integrated │ 6
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START
BY
MASTER
START
BY
MASTER
START
BY
MASTER
REPEAT
START
BY
MASTER
ADDRESS
BYTE
ADDRESS BYTE
ADDRESS
BYTE
ACK BY
MASTER
ACK BY
MASTER
LEAST-SIGNIFICANT
DATA BYTE
ACK BY
MAX6625
POINTER BYTE
MOST-SIGNIFICANT
DATA BYTE
ACK BY
MAX6625
ACK BY
MASTER
DATA
BYTE
NO
ACK BY
MASTER
(c) TYPICAL 1-BYTE READ FROM CONFIGURATION REGISTER WITH PRESET POINTER
ACK BY
MAX6625
STOP
COND BY
MASTER
(b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMP, THIGH, TLOW
ADDRESS
BYTE
MOST-SIGNIFICANT
DATA BYTE
(a) TYPICAL 2-BYTE READ FROM PRESET POINTER LOCATION SUCH AS TEMP, THIGH, TLOW
ACK BY
MAX6625
LEAST-SIGNIFICANT
DATA BYTE
NO ACK BY
MASTER
NO
ACK BY
MASTER
STOP
COND BY
MASTER
STOP
COND BY
MASTER
MAX6625/MAX6626
I2C-Compatible
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
Figure 4. I2C-Compatible Timing Diagram
Maxim Integrated │ 7
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
SDA
INTERFACE
SCL
DATA
ADDRESS
POINTER REGISTER
(SELECTS REGISTER FOR
COMMUNICATION)
REGISTER SELECT
TEMPERATURE
(READ ONLY)
POINTER = 00000000
CONFIGURATION
(READ-WRITE, SETS OPERATING MODES)
POINTER = 00000001
THIGH SET-POINT
(READ-WRITE)
POINTER = 00000011
TLOW SET-POINT
(READ-WRITE)
POINTER = 00000010
Figure 5. MAX6625/MAX6626 Programmers Model
Table 1. Address Selection
ADD CONNECTION
I2C-COMPATIBLE ADDRESS
GND
100 1000
VS
100 1001
SDA
100 1010
SCL
100 1011
Control Registers
Five registers control the operation of the MAX6625/
MAX6626 (Figure 5 and Tables 2 through 7). The pointer
register should be the first addressed and determines
which of the other four registers are acted on. The other
four are the temperature, configuration, high-temperature
(THIGH), and low-temperature (TLOW) registers. The
temperature register is 9 bits for the MAX6625 and 12
bits for the MAX6626, read only, and contains the latest
temperature data. The register length is 16 bits with the
unused bits masked to zero. The digital temperature data
contained in the temperature register is in °C, using a
two’s-complement format with 1 LSB corresponding to
0.5°C for the MAX6625 and 0.0625°C for the MAX6626
(Table 8).
The configuration register is 8 bits, read/write, and contains the fault queue depth, the temperature alarm polarity
select bit, the interrupt mode select bit, and the shutdown
control bit. The high-temperature register is 9 bits, read/
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write, and contains the value that triggers the overtemperature alarm. The low-temperature register is 9 bits, read/
write, and contains the value to which the temperature
must fall before the overtemperature alarm is deasserted,
if in comparator mode.
Temperature Conversion
An on-chip bandgap reference produces a signal proportional to absolute temperature (PTAT), as well as
the temperature-stable reference voltage necessary for
the analog-to-digital conversion. The PTAT signal is
digitized by the on-board ADC to a resolution of 0.5°C
for the MAX6625, and 0.0625°C for the MAX6626. The
resulting digital value is placed in the temperature register. The temperature conversion runs continuously and
asynchronously from the I2C-compatible interface at a
rate of 133ms per conversion. When the temperature
register is read, the most recently completed conversion
result is provided and the currently active conversion is
aborted. When the bus transaction is finished by an I2Ccompatible stop condition conversions resume.
Overtemperature Alarm
The dedicated overtemperature output pin, OT, has
programmable polarity and two modes: comparator
and interrupt. Polarity and mode are selected through
the configuration register, and alarm activity is governed by a fault queue. Fault queue depth is also
selected through the configuration register (Tables 5
and 6). The MAX6625P/MAX6626P OT output is open
Maxim Integrated │ 8
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Table 2. Pointer Register
D7
D6
D5
D4
D3
D2
0
0
0
0
0
0
D1
D0
Register select
(see Table 3)
D7 to D2: Read all zeros, cannot be written.
Table 3. Register Select
D1
D0
REGISTER
0
0
Temperature (default)
0
1
Configuration
1
0
TLOW
1
1
THIGH
Table 4. Temperature Register
PART
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3–D0
MAX6625
MSB
(Sign)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB
0
0
0
0
MAX6626
MSB
(Sign)
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB
0
D6 to D0, MAX6625: Read all zeros, cannot be written.
D3 to D0, MAX6626: Read all zeros, cannot be written.
D15: MSB is the sign bit.
1 LSB = 0.5°C for the MAX6625.
1 LSB = 0.0625°C for the MAX6626.
Temperature is stored in two’s-complement format.
Table 5. Configuration Register
Table 6. Fault Queue Depth
D7
D6
D5
0
0
0
D4
D3
Fault
Queue
Depth
D2
D1
D0
OT
Polarity
Comparator
or Interrupt
Mode
Shutdown
All defaults = 0.
D0: 0 = Normal operation, 1 = Shutdown.
D1: 0 = Comparator mode, 1 = Interrupt mode.
D2: 0 = Active low, 1 = Active high.
D7 to D5: Reserved locations, always write zeros.
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D4
D3
NO. OF FAULTS
0
0
1 (default)
0
1
2
1
0
4
1
1
6
Maxim Integrated │ 9
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Table 7. THIGH and TLOW Registers
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
MSB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB
0
0
0
0
0
0
0
D6 to D0: Read all zeros, cannot be written.
D15: MSB is the sign bit.
Default: THIGH = +80°C (5000h), TLOW = +75°C (4B00h).
LSB = 0.5°C.
Table 8. Output Code vs. Temperature
DIGITAL OUTPUT CODE
TEMPERATURE
(°C)
MAX6625
MSB
+125.0000
MAX6626
BINARY
LSB
HEX
0111 1101 0000 0000
7D00
+124.9375
0111 1100 1000 0000
+25.0000
0001 1001 0000 0000
+0.5000
BINARY
MSB
LSB
HEX
0111 1101 0000 0000
7D00
7C80
0111 1100 1111 0000
7CF0
1900
0001 1001 0000 0000
1900
0000 0000 1000 0000
0080
0000 0000 1000 0000
0080
0.0000
0000 0000 0000 0000
0000
0000 0000 0000 0000
0000
-0.5000
1111 1111 1000 0000
FF80
1111 1111 1000 0000
FF80
-25.0000
1110 0111 0000 0000
E700
1110 0111 0000 0000
E700
-55.0000
1100 1001 0000 0000
C900
1100 1001 0000 0000
C900
*
1000 0000 0000 0000
8000
1000 0000 0000 0000
8000
*8000h is the default value at power-up and after coming out of shutdown.
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Maxim Integrated │ 10
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
THIGH
DIE
TEMPERATURE
TLOW
OT
(COMPARATOR MODE)
OT
(INTERRUPT MODE)
*
*
*
*THIS ASSUMES DEASSERTION OF OT BY A
MASTER THROUGH THE SERIAL INTERFACE.
SEE INTERRUPT MODE SECTION.
TEMPERATURE RESPONSE
SHOWN WITH OT SET FOR
ACTIVE LOW
TIME
Figure 6. OT Alarm Output and Reset Diagram
drain, and the MAX6625R/MAX6626R output includes an
internal 35kΩ (typ) pullup resistor. Figure 6 shows the OT
alarm operation and reset details.
Fault Queue
A programmable fault queue on the MAX6625/MAX6626
eliminates spurious alarm activity in noisy environments.
The queue sets the number of consecutive out-of-tolerance temperature readings that must occur before the
OT alarm output is toggled. An out-of-tolerance reading
is above THIGH or below TLOW. The fault queue depth
defaults to one at power-up and may be programmed
to one, two, four, or six consecutive conversions. Any
time the conversion result is in tolerance, and OT is not
asserted, the queue is cleared, even if it contains some
out-of-tolerance counts. Additionally, the fault queue
automatically clears at power-up, in shutdown, or if a
master writes to any of the THIGH, TLOW, or configuration registers. Whenever the fault queue is cleared, OT
is deasserted.
For example, the fault queue is set to four, two consecutive out-of-tolerance readings have occurred, and the
master writes to the TLOW register. The fault queue is
cleared and begins to look for four new consecutive outof-tolerance conversions.
Comparator Mode
In comparator mode, OT is asserted when the number
of consecutive conversions exceeding the value in the
THIGH register is equal to the depth of the fault queue. OT
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deasserts when the number of consecutive conversions
less than the value in the TLOW register is equal to the
depth of the fault queue. THIGH minus TLOW is the effective hysteresis of the OT output.
For example, if THIGH is set to +100°C, TLOW is set to
+80°C, and the fault queue depth is set to four, OT does
not assert until four consecutive conversions exceed
+100°C. Then, OT does not deassert until four consecutive conversions are less than +80°C.
Comparator mode allows autonomous clearing of an OT
fault without the intervention of a master and is ideal to
use for driving a cooling fan (Figure 7).
Interrupt Mode
In interrupt mode, the MAX6625/MAX6626 look for a
THIGH or a TLOW fault based on previous fault activity.
The OT pin asserts an alarm for an undertemperature
fault, as well as for an overtemperature fault, depending on certain conditions. If the fault queue is cleared at
power-up, the IC looks for a THIGH fault. After a THIGH
fault, the IC looks for a TLOW fault. After a TLOW fault, the
IC looks for a THIGH fault, and it bounces back and forth
if properly deasserted each time. Once either fault has
occurred, it remains active indefinitely until deasserted by
a read of any register, and the device then begins to look
for a fault of the opposite type. Also, if the fault queue is
cleared, OT is deasserted and the IC once again looks for
a THIGH fault. The activation of any fault is subject to the
depth of the fault queue.
Maxim Integrated │ 11
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Example 1: If THIGH is set to +100°C, TLOW is set to
+80°C, and the fault queue depth is set to four, OT does
not assert until four consecutive conversions exceed
+100°C. If the temperature is then read through the I2Ccompatible interface, OT deasserts. OT asserts again
when four consecutive conversions are less than +80°C.
Example 2: If THIGH is set to +100°C, TLOW is set to
+80°C, and the fault queue depth is set to four, OT does
not assert until four consecutive conversions exceed
+100°C. If the THIGH register is then changed to +120°C,
OT deasserts and the IC looks for a new THIGH fault.
Shutdown
The MAX6625/MAX6626 offer a low-power shutdown
mode. Enter shutdown mode by programming the shutdown bit of the control register high. In shutdown, the temperature register is set to 8000h and the ADC is turned off,
reducing the device current draw to 1μA (typ). After coming out of shutdown, the temperature register continues to
read 8000h until the first conversion result appears. The
fault queue is held in reset during shutdown.
Thermal Considerations
The MAX6625/MAX6626 supply current is less than
1mA when the I2C-compatible interface is active. When
used to drive high-impedance loads, the devices dissipate negligible power; therefore, the die temperature
is essentially the same as the package temperature.
The key to accurate temperature monitoring is good thermal contact between the MAX6625/MAX6626 package
and the monitored device or circuit. In some applications,
the 6-pin SOT23 package may be small enough to fit
underneath a socketed μP, allowing the device to monitor the μP’s temperature directly. Heat flows in and out of
plastic packages primarily through the leads. Short, wide
copper traces leading to the temperature monitor ensure
that heat transfers quickly and reliably. The rise in die
temperature due to self-heating is given by the following
formula:
ΔTJ = PD x θJA
where PD is the power dissipated by the MAX6625/
MAX6626, and θJA is the package’s thermal resistance.
The typical thermal resistance is +110°C/W for the 6-pin
SOT23 package. To limit the effects of self-heating, minimize the output currents. For example, if the MAX6625/
MAX6626 sink 4mA with the maximum OT VL specification of 0.8V, an additional 3.2mW of power is dissipated
within the IC. This corresponds to a 0.35°C rise in the die
temperature.
Applications
Figure 7 shows the MAX6625/MAX6626 used as a
temperature-triggered fan controller. Figure 8 shows the
MAX6625/MAX6626 used as a thermostat to control a
heating element.
+VS
+3V TO +5V
+VS
+3V TO +5V
+12V
HEATER
12V 300mA
FAN MOTOR
6
OT
MAX6625R
MAX6626R
4
6
LOGIC LEVEL
MOSFET
4k
MAX6625P
MAX6626P
OT
5
2
3
Figure 7. Fan Controller
www.maximintegrated.com
RELAY
5VDC, 20mA
125VAC, 1A
2N3904
HEATER
SUPPLY
Figure 8. Simple Thermostat
Maxim Integrated │ 12
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Chip Information
Selector Guide
ALARM
OUTPUT
RESOLUTION
(BITS)
TOP
MARK
MAX6625PMUT
Open-Drain
9
AAHY
MAX6625RMUT
Internal Pullup
9
AAHZ
MAX6626PMUT
Open-Drain
12
AANP
MAX6626RMUT
Internal Pullup
12
AANQ
PART
Ordering Information(continued)
PART
TEMP RANGE
PIN-PACKAGE
PROCESS: BiCMOS
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.
MAX6625RMUT#G16
-55°C to +125°C
6 SOT23
MAX6625PMUT#G16
-55°C to +125°C
6 SOT23
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
MAX6625RMUT#TG16
-55°C to +125°C
6 SOT23
6 SOT23
U6F-6
21-0058
90-0175
MAX6625PMUT#TG16
-55°C to +125°C
6 SOT23
6 SOT23
U6FH-6***
21-0058
90-0175
MAX6626PMUT#G16
-55°C to +125°C
6 SOT23
6 TDFN-EP
T633-1
21-0137
90-0058
MAX6626RMUT#G16
-55°C to +125°C
6 SOT23
MAX6626PMUT#TG16
-55°C to +125°C
6 SOT23
MAX6626RMUT#TG16
-55°C to +125°C
6 SOT23
*** Package code for RoHS-Compliant parts
*For device options, see Selector Guide at end of data sheet.
Requires special solder temperature profile described in the
Absolute Maximum Ratings section.
**EP = Exposed pad.
# Indicates an RoHS-compliant part
www.maximintegrated.com
Maxim Integrated │ 13
MAX6625/MAX6626
9-Bit/12-Bit Temperature Sensors with
Serial Interface in a SOT23
I2C-Compatible
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
5
11/12
Updated Table 4 and corrected hexadecimal formatting
6
11/14
Updated the Selector Guide
7
6/16
Updated Ordering Information and Package Information tables
DESCRIPTION
5, 9, 10, 12
13
1, 13
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.
© 2016 Maxim Integrated Products, Inc. │ 14
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