19-2047; Rev 4; 5/10
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 compati-
ble, allowing the MAX6629–MAX6632 to be readily con-
nected 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-digi-
tal conversion once every 8s and require minimal aver-
age 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 sec-
ond by reading the conversion results more often.
♦
Low Power Consumption
32µA typ (MAX6631/MAX6632)
200µA typ (MAX6629/MAX6630)
♦
12-Bit + Sign Resolution with 0.0625°C/LSB
♦
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)
Features
MAX6629–MAX6632
Ordering Information
PART
MAX6629MTT+
MAX6629MUT
MAX6630MTT+
MAX6630MUT
MAX6631MTT+
MAX6631MUT
MAX6632MTT+
MAX6632MUT
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
PIN-PACKAGE
6 TDFN-EP*
6 SOT23-6
6 TDFN-EP*
6 SOT23-6
6 TDFN-EP*
6 SOT23-6
6 TDFN-EP*
6 SOT23-6
Applications
Cellular
Hard Disk Drive
HVAC
SPI is a trademark of Motorola, Inc.
Automotive
Industrial Control
Systems
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Typical Application Circuit
+3V TO +5.5V
V
CC
Pin Configurations
TOP VIEW
0.1μF
MAX6629
MAX6630
MAX6631
MAX6632
N.C.
1
6
SO
GND
1
6
SO
SO
GND
2
MAX6629
MAX6631
5
CS
N.C.
2
MAX6630
MAX6632
5
CS
μC
CS
V
CC
3
4
SCK
V
CC
3
4
SCK
SOT23
TDFN
GND
SCK
SOT23
TDFN
________________________________________________________________
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.
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
MAX6629–MAX6632
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
V
CC
...........................................................................-0.3V, +6.0V
SO, SCK,
CS
....................................................-0.3V, V
CC
+ 0.3V
SO .......................................................................-1mA to +50mA
Current into Any Pin ............................................................10mA
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 9.10mW/°C above +70°C)..........727mW
6-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW
Note:
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
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
(V
CC
= +3.0V to +5.5V, T
A
= -55°C to +125°C, unless otherwise noted. Typical values are at V
CC
= +3.3V and T
A
= +25°C.) (Notes 2
and 3)
PARAMETER
TEMPERATURE
T
A
= room temp, V
CC
= +3.3V
0°C
-20°C
Accuracy
-20°C
-40°C
T
A
Power-Supply Sensitivity
Resolution
Time Between Conversion
Starts
Conversion Time
POWER SUPPLY
Supply Voltage Range
Supply Current, SCK Idle
V
CC
I
SD
I
IDLE
I
CONV
Average Operating Current
Power-On Reset (POR)
Threshold
I
CC
Shutdown (Note 3), V
CC
= +0.8V
ADC idle (Figure 2),
CS
= low
ADC converting (Figure 2)
MAX6629, MAX6630
MAX6631, MAX6632
V
CC
falling
6
360
200
32
1.6
3.0
5.5
5
20
650
400
50
μA
V
μA
V
t
SAMPLE
t
CONV
MAX6629, MAX6630,
CS
high
MAX6631, MAX6632,
CS
high
PSS
0.0625
0.37
5.9
180
0.5
8
250
0.65
10.5
320
T
A
T
A
T
A
T
A
+70°C, V
CC
= +3.3V
+85°C, V
CC
= +3.3V
+100°C, V
CC
= +3.3V
+125°C, V
CC
= +3.3V
-0.8
-1.0
-1.6
-2.3
-3.2
-1.0
-5.0
±0.2
±0.2
+0.3
+0.5
+0.8
+1.5
+1.5
0.2
+0.8
+1.0
+1.6
+2.3
+3.2
+3.5
+6.5
0.6
°C/V
°C
s
ms
°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
-55°C, V
CC
= +3.3V
T
A
= +150°C, V
CC
= +3.3V
2
_______________________________________________________________________________________
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, T
A
= -55°C to +125°C, unless otherwise noted. Typical values are at V
CC
= +3.3V and T
A
= +25°C.) (Notes 2
and 3)
PARAMETER
LOGIC INPUTS (CS, SCK)
Logic Input Low Voltage
Logic Input High Voltage
Input Leakage Current
LOGIC OUTPUTS (SO)
Output Low Voltage
Output High Voltage
Serial Clock Frequency
SCK Pulse Width High
SCK Pulse Width Low
CS
Fall to SCK Rise
CS
Fall to Output Enable
CS
Rise to Output Disable
SCK Fall to Output Data Valid
V
OL
V
OH
f
SCL
t
CH
t
CL
t
CSS
t
DV
t
TR
t
DO
C
LOAD
= 10pF
C
LOAD
= 10pF
C
LOAD
= 10pF
C
LOAD
= 10pF
100
100
80
80
50
80
I
SINK
= 1.6mA
I
SOURCE
= 1.6mA
V
CC
- 0.4
5
0.4
V
V
MHz
ns
ns
ns
ns
ns
ns
V
IL
V
IH
I
LEAK
V
IN
= V
GND
or +5.5V
0.7 x
V
CC
±1
±5
0.3 x
V
CC
V
V
μA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX6629–MAX6632
TIMING CHARACTERISTICS (Notes 4 and 5)
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:
C
LOAD
= total capacitance of one bus line in picofarads.
_______________________________________________________________________________________
3
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
MAX6629–MAX6632
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
OPERATING SUPPLY CURRENT
vs. TEMPERATURE
V
CC
= +5.5V
350
SUPPLY CURRENT (μA)
300
250
200
150
MAX6629
100
-55 -30
-5
20
45
70
95
120 145
TEMPERATURE (°C)
V
CC
= +3.3V
V
CC
= +3.6V
V
CC
= +3.0V
V
CC
= +4.5V
MAX6629-32 toc01
POWER-ON RESET (POR)
THRESHOLD vs.TEMPERATURE
MAX6629-32 toc02
TEMPERATURE ERROR
vs. TEMPERATURE
MAX6629-32 toc03
400
V
CC
= +5.0V
2.6
2.4
POWER-ON RESET THRESHOLD (V)
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
-55 -30
-5
20
45
70
95
120 145
TEMPERATURE (°C)
3
2
TEMPERATURE ERROR (°C)
1
0
-1
-2
-3
-4
-55 -30
-5
20
45
70
TEMPERATURE (°C)
MAX6629
95
120 145
TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6629-32 toc04
RESPONSE TO THERMAL SHOCK
125
100
TEMPERATURE (°C)
75
50
25
0
MAX6629-32 toc05
12
10
TEMPERATURE ERROR (°C)
8
6
V
IN
= SQUARE WAVE
APPLIED TO V
CC
WITH NO
0.1μF CAPACITOR
V
IN
= 250mV
P-P
4
2
0
10
100
1k
10k
100k
1M
10M 100M
FREQUENCY (Hz)
-2
0
2
4
6
TIME (s)
8
10
12
14
Pin Description
PIN
MAX6629
MAX6631
1
2
MAX6630
MAX6632
2
1
N.C.
GND
No Connect. Connect to ground plane for better thermal performance to the PC board.
Ground
Supply Voltage Input. Bypass V
CC
to GND with a 0.1μF capacitor. V
CC
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.
Serial Clock Input
Chip-Select Input. Enables the interface. A rising edge off
CS
initiates the next
conversion. Pulling
CS
low initiates an idle state.
Serial Data Output
Exposed Pad (TDFN only). Connect to GND or leave unconnected.
NAME
FUNCTION
3
3
V
CC
4
5
6
—
4
5
6
—
SCK
CS
SO
EP
4
_______________________________________________________________________________________
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 inter-
faces. This interface can also be connected to virtually
any processor, which has at least three general-pur-
pose 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. This extended temperature
range makes it especially useful in automotive under-
hood applications. 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
LOGIC LINE WHERE V
LOGIC
> 3V
V
CC
MAX6629–MAX6632
MAX6629
MAX6630
MAX6631
MAX6632
GND
SO
SCK
CS
Figure 1. Powering the Sensor from a Logic Gate
is not noisy, as excessive noise on V
CC
can affect tem-
perature measurement accuracy.
ADC Conversion Sequence
The MAX6629–MAX6632 continuously convert temper-
ature to digital data. Setting
CS
low stops any conver-
sion 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 seri-
al-interface 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
MAX6629
MAX6630
0.25s ADC CONVERSION TIME
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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