Maxim MAX6631 12-bit sign digital temperature sensors with serial interface Datasheet

19-2047; Rev 1; 7/01
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
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.
Features
♦ 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
±2.3°C (max) from -20°C to +100°C
±3.2°C (max) from -40°C to +125°C
±6.5°C (max) at +150°C
♦ +150°C Extended Temperature Range
♦ SPI-Compatible Serial Interface
♦ +3.0V to +5.5V Supply Range
♦ 6-Pin SOT23 Package
Ordering Information
Applications
Cellular
Automotive
Hard Disk Drive
Industrial Control
Systems
HVAC
SPI is a trademark of Motorola, Inc.
PART
TEMP. RANGE
PINPACKAGE
TOP
MARK
MAX6629MUT-T
-55°C to +150°C
6 SOT23-6
AAPM
MAX6630MUT-T
-55°C to +150°C
6 SOT23-6
AAPN
MAX6631MUT-T
-55°C to +150°C
6 SOT23-6
AAPO
MAX6632MUT-T
-55°C to +150°C
6 SOT23-6
AAPP
Typical Application Circuit
+3V TO +5.5V
VCC
Pin Configurations
MAX6629
MAX6630
MAX6631
MAX6632
0.1µF
TOP VIEW
SO
N.C. 1
µC
CS
GND
SCK
GND 2
MAX6629
MAX6631
VCC 3
SOT23
6
SO
GND 1
5
CS
N.C. 2
4
SCK
VCC 3
MAX6630
MAX6632
6
SO
5
CS
4
SCK
SOT23
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX6629–MAX6632
General Description
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
Junction Temperature ......................................................+150°C
Operating Temperature Range (Note 1) ...........-55°C to +150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature .............................................................Note 2
Note 1: It is not recommended to operate the device above +125°C for extended periods of time.
Note 2: 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, JEDEC 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
(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 3
and 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
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
UNITS
TEMPERATURE
Accuracy
Power-Supply Sensitivity
-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
2
3.0
Shutdown (Note 4), VCC = +0.8V
IIDLE
ADC idle (Figure 2), CS = low
ICONV
ICC
5
6
20
ADC converting (Figure 2)
360
650
MAX6629, MAX6630
200
400
MAX6631, MAX6632
32
50
VCC falling
1.6
_______________________________________________________________________________________
µA
µA
V
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
(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 3
and 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.3 x
VCC
V
LOGIC INPUTS (CS, SCK)
Logic Input Low Voltage
VIL
Logic Input High Voltage
VIH
Input Leakage Current
ILEAK
0.7 x
VCC
V
±1
VIN = GND or +5.5V
±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 5 and 6)
Serial Clock Frequency
fSCL
SCK Pulse Width High
tCH
100
5
ns
SCK Pulse Width Low
tCL
100
ns
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
MHz
ns
Note 3: Tested at a single temperature. Specifications over temperature are guaranteed by design.
Note 4: 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 5: Timing characteristics are guaranteed by design and are not production tested.
Note 6: CLOAD = total capacitance of one bus line in picofarads.
_______________________________________________________________________________________
3
MAX6629–MAX6632
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = +3.3V, TA = +25°C, unless otherwise noted.)
POWER-ON RESET (POR)
THRESHOLD vs.TEMPERATURE
VCC = +5.0V
2.4
300
VCC = +3.3V
250
VCC = +3.6V
VCC = +3.0V
200
150
3
2.2
2
TEMPERATURE ERROR (°C)
350
2.6
MAX6629-32 toc02
VCC = +4.5V
POWER-ON RESET THRESHOLD (V)
VCC = +5.5V
MAX6629-32 toc01
400
TEMPERATURE ERROR vs.
TEMPERATURE
2.0
1.8
1.6
1.4
1.2
-55 -30
-5
20
45
70
95
-5
20
45
70
95
120 145
MAX6629
-55 -30
-5
45
70
95
120 145
TEMPERATURE (°C)
MAX6629-32 toc05
MAX6629-32 toc04
VIN = SQUARE WAVE
APPLIED TO VCC WITH NO
0.1µF CAPACITOR
20
RESPONSE TO THERMAL SHOCK
125
100
8
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
-2
TEMPERATURE (°C)
TEMPERATURE ERROR vs.
POWER-SUPPLY NOISE FREQUENCY
10
-1
-4
-55 -30
120 145
TEMPERATURE (°C)
12
0
-3
0.6
100
1
1.0
0.8
MAX6629
MAX6629-32 toc03
OPERATING SUPPLY CURRENT vs.
TEMPERATURE
SUPPLY CURRENT (µA)
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
6
VIN = 250mVp-p
4
75
50
25
2
0
0
10
100
1k
10k
100k
1M
10M 100M
FREQUENCY (Hz)
-2
0
2
4
6
8
10
12
14
TIME (s)
Pin Description
PIN
4
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
_______________________________________________________________________________________
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
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. This extended temperature
range especially makes it useful in automotive underhood 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
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
is not noisy, as excessive noise on VCC can affect temperature measurement accuracy.
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 serial-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
CONVERSION PERIOD
0.5s
MAX6631
MAX6632
0.25s ADC CONVERSION TIME
MAX6631
MAX6632
CONVERSION PERIOD
8s
Figure 2. Conversion Time and Rate Relationships
_______________________________________________________________________________________
5
MAX6629–MAX6632
Detailed Description
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)
TEMPERATURE
(°C)
DIGITAL OUTPUT (BINARY)
D15–D3
D2
D1, D0
150
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
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
D7
D6
D5
D4
D3
D2
D1
D0
LSB
Data
Low
High-Z
High-Z
undefined and are always in high-impedance mode
(Table 1). The power-up state for SO is high impedance. Figure 3 shows the detailed serial timing specifications for the SPI port. The temperature data format is
in two's complement format (Table 2).
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
finish. CS’s falling edge stops any conversion in
progress, and data is latched into the shift register.
Then the data clocks 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
6
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.
_______________________________________________________________________________________
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
Functional Block 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.
VOLTAGE
REFERENCE
MAX6629
MAX6630
MAX6631
MAX6632
TEMPERATURE
SENSOR
12-BIT + SIGN
∑∆ ADC
SPI-COMPATIBLE
INTERFACE
CS
SCK
SO
Chip Information
TRANSISTOR COUNT: 6475
PROCESS: BiCMOS
The rise in die temperature due to self-heating is given
by the following formula:
∆TJ = PDISSIPATION x θJA
where P DISSIPATION 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.
_______________________________________________________________________________________
7
MAX6629–MAX6632
Applications Information
MAX6629–MAX6632
12-Bit + Sign Digital Temperature Sensors
with Serial Interface
6LSOT.EPS
Package Information
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
Similar pages