MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
General Description
The MAX6629–MAX6632 are local digital temperature
sensors with an SPI-compatible serial interface. The
temperature is converted to a 12-bit + sign word with a
resolution of 0.0625°C/LSB. An extended temperature
range provides useful readings up to +150°C.
These sensors are 3-wire serial interface SPI compatible,
allowing the MAX6629–MAX6632 to be readily connected
to a variety of microcontrollers (μCs). The MAX6629–
MAX6632 are read-only devices, simplifying their use in
systems where only temperature data is required.
All four digital temperature sensors require very little
supply current, making them ideal for portable systems.
The MAX6631/MAX6632 perform a temperature-to-digital
conversion once every 8s and require minimal average
supply current, 32μA (typ). The MAX6629/MAX6630
perform a conversion once every 0.5s and require only
200μA (typ) supply current. Any of these temperature
sensors can perform conversions more often—up to
approximately four conversions per second by reading the
conversion results more often.
Applications
●● Cellular
●● Hard Disk Drive
●● HVACs
●● Industrial Control
●● Systems
+3V TO +5.5V
●● Accuracy
• ±1°C (max) from 0°C to +70°C
●● +150°C Extended Temperature Range
●● SPI-Compatible Serial Interface
●● +3.0V to +5.5V Supply Range
●● 6-Pin TDFN and SOT23 Packages
●● Lead-Free Version Available (TDFN Package)
Ordering Information
PART
MAX6629
MAX6630
MAX6631
MAX6632
PIN-PACKAGE
-55°C to +125°C
6 TDFN-EP*
MAX6629MUT#G16
-55°C to +125°C
6 SOT23
MAX6630MTT+
-55°C to +125°C
6 TDFN-EP*
MAX6630MUT#G16
-55°C to +125°C
6 SOT23
MAX6631MTT+
-55°C to +125°C
6 TDFN-EP*
MAX6632MTT+
-55°C to +125°C
6 TDFN-EP*
MAX6632MUT#G16
-55°C to +125°C
6 SOT23
TOP VIEW
N.C. 1
SO
CS
SCK
µC
GND 2
MAX6629
MAX6631
VCC 3
SOT23
TDFN
19-2047; Rev 6; 11/16
TEMP RANGE
MAX6629MTT+
Pin Configurations
VCC
GND
●● 12-Bit + Sign Resolution with 0.0625°C/LSB
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Typical Application Circuit
0.1µF
Features
●● Low Power Consumption
• 32μA typ (MAX6631/MAX6632)
• 200μA typ (MAX6629/MAX6630)
6
SO
GND 1
5
CS
N.C. 2
4
SCK
VCC 3
MAX6630
MAX6632
SOT23
TDFN
6
SO
5
CS
4
SCK
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Absolute Maximum Ratings
All voltages referenced to GND.
VCC...........................................................................-0.3V, +6.0V
SO, SCK, CS....................................................-0.3V, VCC + 0.3V
SO .......................................................................-1mA to +50mA
Current into Any Pin ............................................................10mA
Continuous Power Dissipation (TA = +70°C)
6-Pin SOT23 (derate 9.10mW/°C above +70°C).........727mW
6-Pin TDFN (derate 24.4mW/°C above +70°C).........1951mW
Junction Temperature......................................................+150°C
Operating Temperature Range (Note 1)...........-55°C to +150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
Soldering Temperature (reflow)
TDFN............................................................................+260°C
SOT23 (Ordering Information contains “#”).................+245°C
SOT23 (Ordering Information contains “-”)..................+240°C
Note 1: It is not recommended to operate the device above +125°C for extended periods of time.
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
(VCC = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes
2 and 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TEMPERATURE
Accuracy
Power-Supply Sensitivity
TA = room temp, VCC = +3.3V
-0.8
±0.2
+0.8
0°C ≤ TA ≤ +70°C, VCC = +3.3V
-1.0
±0.2
+1.0
-20°C ≤ TA ≤ +85°C, VCC = +3.3V
-1.6
+0.3
+1.6
-20°C ≤ TA ≤ +100°C, VCC = +3.3V
-2.3
+0.5
+2.3
-40°C ≤ TA ≤ +125°C, VCC = +3.3V
-3.2
+0.8
+3.2
TA ≥ -55°C, VCC = +3.3V
-1.0
+1.5
+3.5
TA = +150°C, VCC = +3.3V
-5.0
+1.5
+6.5
0.2
0.6
PSS
Resolution
Time Between Conversion
Starts
Conversion Time
0.0625
tSAMPLE
°C
°C/V
°C
MAX6629, MAX6630, CS high
0.37
0.5
0.65
MAX6631, MAX6632, CS high
5.9
8
10.5
180
250
320
ms
5.5
V
tCONV
s
POWER SUPPLY
Supply Voltage Range
VCC
ISD
Supply Current, SCK Idle
Average Operating Current
Power-On Reset (POR)
Threshold
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3.0
Shutdown (Note 3), VCC = +0.8V
5
IIDLE
ADC idle (Figure 2), CS = low
6
20
ICONV
ADC converting (Figure 2)
360
650
MAX6629, MAX6630
200
400
MAX6631, MAX6632
32
50
VCC falling
1.6
ICC
µA
µA
V
Maxim Integrated │ 2
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Electrical Characteristics (continued)
(VCC = +3.0V to +5.5V, TA = -55°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Notes
2 and 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS (CS, SCK)
Logic Input Low Voltage
VIL
Logic Input High Voltage
VIH
Input Leakage Current
ILEAK
0.3 x
VCC
0.7 x
VCC
VIN = VGND or +5.5V
V
V
±1
±5
µA
0.4
V
LOGIC OUTPUTS (SO)
Output Low Voltage
VOL
ISINK = 1.6mA
Output High Voltage
VOH
ISOURCE = 1.6mA
VCC - 0.4
V
TIMING CHARACTERISTICS (Notes 4 and 5)
Serial Clock Frequency
fSCL
SCK Pulse Width High
tCH
100
ns
SCK Pulse Width Low
tCL
100
ns
5
MHz
CS Fall to SCK Rise
tCSS
CLOAD = 10pF
CS Fall to Output Enable
tDV
CLOAD = 10pF
80
ns
CS Rise to Output Disable
tTR
CLOAD = 10pF
50
ns
SCK Fall to Output Data Valid
tDO
CLOAD = 10pF
80
ns
80
ns
Note 2: Tested at a single temperature. Specifications over temperature are guaranteed by design.
Note 3: The MAX6629–MAX6632 are not specifically equipped with a shutdown function. Their low supply current permits powering
them from the output of a logic gate. This specification is given to ensure that the MAX6629–MAX6632 do not draw excessive currents at low supply voltages, ensuring reliable operation from a gate output.
Note 4: Timing characteristics are guaranteed by design and are not production tested.
Note 5: CLOAD = total capacitance of one bus line in picofarads.
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Maxim Integrated │ 3
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Typical Operating Characteristics
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
VCC = +3.3V
250
VCC = +3.6V
VCC = +3.0V
200
150
100
MAX6629
-55 -30
-5
20
45
70
95
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
120 145
-55 -30
TEMPERATURE (°C)
45
70
95
2
1
0
-1
-2
-3
-4
120 145
MAX6629
-55 -30
-5
TEMPERATURE (°C)
VIN = SQUARE WAVE
APPLIED TO VCC WITH NO
0.1µF CAPACITOR
20
45
6
VIN = 250mVP-P
4
2
10
100
1k
10k
100k
1M
10M 100M
95
120 145
RESPONSE TO THERMAL SHOCK
125
100
8
70
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
20
TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
10
0
-5
MAX6629-32 toc04
12
3
MAX6629-32 toc03
2.4
TEMPERATURE ERROR
vs. TEMPERATURE
MAX6629-32 toc05
SUPPLY CURRENT (µA)
300
2.6
TEMPERATURE ERROR (∞C)
VCC = +5.0V
350
POWER-ON RESET (POR)
THRESHOLD vs.TEMPERATURE
MAX6629-32 toc02
VCC = +5.5V VCC = +4.5V
POWER-ON RESET THRESHOLD (V)
400
MAX6629-32 toc01
OPERATING SUPPLY CURRENT
vs. TEMPERATURE
75
50
25
0
-2
0
FREQUENCY (Hz)
2
4
6
8
10
12
14
TIME (s)
Pin Description
PIN
NAME
FUNCTION
MAX6629
MAX6631
MAX6630
MAX6632
1
2
N.C.
No Connect. Connect to ground plane for better thermal performance to the PC board.
2
1
GND
Ground
3
3
VCC
Supply Voltage Input. Bypass VCC to GND with a 0.1µF capacitor. VCC can also be
powered from a logic output as long as the voltage level is greater than 3.0V and the logic
output is not noisy. Setting the logic output low provides a hardware shutdown mode.
4
4
SCK
Serial Clock Input
5
5
CS
Chip-Select Input. Enables the interface. A rising edge off CS initiates the next conversion.
Pulling CS low initiates an idle state.
6
6
SO
Serial Data Output
—
—
EP
Exposed Pad (TDFN only). Connect to GND or leave unconnected.
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Maxim Integrated │ 4
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Detailed Description
The MAX6629–MAX6632 are local digital temperature
sensors with a serial bus. The MAX6629–MAX6632 are
typically interfaced to a μC in temperature sensing and
control applications. The MAX6629–MAX6632 convert
temperature to a 12-bit + sign word with a 0.0625°C LSB.
The data is communicated through a simple serial interface with a CS (chip select) line, SO (data) line, and SCK
(clock) line. This interface can be directly connected to,
and is fully compatible with, SPI interfaces. This interface
can also be connected to virtually any processor, which
has at least three general-purpose input/output (GPIO)
lines available to implement software “bit banging.”
The high resolution of the MAX6629–MAX6632 makes
them especially useful in thermal control loops, HVAC
systems, or in any system where quick anticipation of
temperature trends is useful. The MAX6629–MAX6632
can produce temperature data in excess of +150°C,
although they are specified for a maximum operating
temperature of +150°C. The low power consumption is
also ideal in battery-operated and portable applications.
The MAX6631/MAX6632 are optimized for minimum
power consumption with their 8s conversions. The
MAX6629/MAX6630 provide faster conversions, 0.5s, at
the expense of power consumption. The low quiescent
supply current enables the device to be powered from
a logic line or the output of a gate where the high level
exceeds 3V, as shown in Figure 1. While the MAX6629–
MAX6632 are not specifically equipped with a software
shutdown mode, the hardware shutdown can easily be
implemented by setting the gate output to low. Pulling
CS low without a clock also puts the device in idle mode.
Take care to ensure that the logic output is not noisy, as
excessive noise on VCC can affect temperature measurement accuracy.
MAX6629
MAX6630
0.25s ADC
CONVERSION TIME
LOGIC LINE WHERE VLOGIC > 3V
VCC
MAX6629
MAX6630
MAX6631
MAX6632
SO
SCK
CS
GND
Figure 1. Powering the Sensor from a Logic Gate
ADC Conversion Sequence
The MAX6629–MAX6632 continuously convert temperature to digital data. Setting CS low stops any conversion
in progress, places the device in idle mode, and makes
data available for reading. Setting CS high starts a new
conversion. CS must remain high for at least 0.3s to allow
for the conversion to be completed. Figure 2 shows the
timing relationship between conversion time and conversion rate.
SPI Digital Interface
The MAX6629–MAX6632 are compatible with SPI serialinterface standards (Figure 3) and are designed to be
read-only devices. CS’s rising edge always starts a new
conversion and resets the interface. CS must stay high
for a minimum of 300ms to allow the conversion to finish.
CS’s falling edge stops any conversion in progress, and
data is latched into the shift register. Then the data clocks
MAX6629
MAX6630
CONVERSION PERIOD
0.5s
MAX6631
MAX6632
0.25s ADC
CONVERSION TIME
MAX6631
MAX6632
CONVERSION PERIOD
8s
Figure 2. Conversion Time and Rate Relationships
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Maxim Integrated │ 5
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
tCSS
CS
SCK
tDV
tDO
tTR
SO
D15
D3
D2
D1
D0
Figure 3. SPI Timing Diagram
Table 1. Data Output Format
D15
D14
Sign
MSB
Data
D13
D12
D11
D10
D9
D8
Table 2. Temperature Data Format
(Two’s Complement)
D15–D3
D2
D1, D0
0,1001,0110,0000
0
XX
125
0,0111,1101,0000
0
XX
25
0,0001,1001,0000
0
XX
0.0625
0,0000,0000,0001
0
XX
150
0
0,0000,0000,0000
0
XX
-0.0625
1,1111,1111,1111
0
XX
-25
1,1110,0111,0000
0
XX
-55
1,1100,1001,0000
0
XX
out at SO on SCK’s falling edge with the sign bit (D15)
first, followed by the MSB. Data is sent in one 16-bit word,
and CS must remain low until all 16 bits are transferred. If
CS goes high in the middle of a transmission, it is necessary to wait the conversion time (less than 300ms) before
attempting a new read. The serial data is composed of 12
+ 1 data bits (D15–D3) and 3 trailing bits (D2–D0). D2 is
always low, serving as the confirmation bit that the device
has been communicated with. The last 2 bits, D0 and D1,
are undefined and are always in high-impedance mode
(Table 1). The power-up state for SO is high impedance.
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D6
D5
D4
D3
D2
D1
D0
LSB
Data
Low
High-Z
High-Z
Figure 3 shows the detailed serial timing specifications
for the SPI port. The temperature data format is in two’s
complement format (Table 2).
DIGITAL OUTPUT (BINARY)
TEMPERATURE
(°C)
D7
Power Shutdown Mode
The MAX6629–MAX6632 do not have a built-in power
software shutdown mode. However, a power shutdown
mode is easily implemented utilizing an unused logic
gate. A typical CMOS or TTL logic output has enough
drive capability to serve as the power source if its output
voltage level exceeds 3V, as shown in Figure 1. Drive the
logic output low to provide a hardware shutdown mode.
Idle Mode
The MAX6629–MAX6632 can be put into idle mode by
pulling CS low. Data can be clocked out when the device
is in idle mode.
Power-On Reset (POR)
The POR supply voltage of the MAX6629–MAX6632 is
typically 1.6V. Below this supply voltage, the interface is
inactive and the data register is set to the POR state, 0°C.
When power is first applied and VCC rises above 1.6V
(typ), the device starts to convert, although temperature
reading is not recommended at VCC levels below 3.0V.
Maxim Integrated │ 6
MAX6629–MAX6632
Applications Information
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Functional Diagram
Thermal Considerations
The key to accurate temperature monitoring is good thermal contact between the MAX6629–MAX6632 package
and the object being monitored. In some applications, the
6-pin SOT23 package is small enough to fit underneath
a socketed μP, allowing the device to monitor the μP’s
temperature directly. Accurate temperature monitoring
depends on the thermal resistance between the object
being monitored and the MAX6629–MAX6632 die. Heat
flows in and out of plastic packages primarily through
the leads. If the sensor is intended to measure the temperature of a heat-generating component on the circuit
board, it should be mounted as close as possible to that
component and should share supply and ground traces (if
they are not noisy) with that component where possible.
This maximizes the heat transfer from the component to
the sensor.
The MAX6629/MAX6630 supply current is typically
200μA, and the MAX6631/MAX6632 supply current is
typically 32μA. When used to drive high-impedance
loads, the device dissipates negligible power. Therefore,
the die temperature is essentially the same as the package temperature.
The rise in die temperature due to self-heating is given by
the following formula:
ΔTJ = PDISSIPATION x θJA
where PDISSIPATION is the power dissipated by the
MAX6629–MAX6632, 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 MAX6629–
MAX6632 sink 1mA, the output voltage is guaranteed
to be less than 0.4V. Therefore, an additional 0.4mW of
power is dissipated within the IC. This corresponds to a
0.044°C shift in the die temperature in the 6-pin SOT23.
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MAX6629
MAX6630
MAX6631
MAX6632
VOLTAGE
REFERENCE
TEMPERATURE
SENSOR
12-BIT + SIGN
∑∆ ADC
CS
SCK
SO
SPI-COMPATIBLE
INTERFACE
Chip Information
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.
PACKAGE
TYPE
PACKAGE
CODE
DOCUMENT
LAND
NO.
PATTERN NO.
6 SOT23
U6FH-6
21-0058
90-0175
6 TDFN-EP
T633+2
21-0137
90-0058
Maxim Integrated │ 7
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Revision History
REVISION
NUMBER
REVISION
DATE
0
5/01
Initial release of MAX6629
1
7/01
Initial release of MAX3360, MAX3361, and MAX3362; changed ICONV from 600µA (max) to
650µA (max) in the Electrical Characteristics table
2
4/04
Changed the lead temperature in the Absolute Maximum Ratings section, replacing Note
2 with +300°C (removed the JEDEC solder reflow boiler plating due to high temp solder
paste for flip chips now in production)
3
8/05
Added the TDFN package
Added “+” to TDFN packages in the Ordering Information table
1
4
5/10
Added soldering information to the Absolute Maximum Ratings section
2
Added the TDFN exposed pad information to the Pin Description table
4
5
6
PAGES
CHANGED
DESCRIPTION
—
1, 2
2
1, 2, 9
10/14
Removed automotive reference from data sheet
11/16
Removed MAX6631MUT from Ordering Information table, changed non lead-free parts to
lead-free parts
1, 5
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.
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