MAX6627 [MAXIM]
Remote 【1∑C Accurate Digital Temperature Sensors with SPI-Compatible Serial Interface; 远程± 1 ° C精度数字温度传感器，带有SPI兼容的串行接口
| 型号： | MAX6627 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Remote 【1∑C Accurate Digital Temperature Sensors with SPI-Compatible Serial Interface |
| 文件： | 总9页 (文件大小：152K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2032; Rev 1; 7/01
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
General Description
Features
The MAX6627/MAX6628 precise digital temperature
sensors report the temperature of a remote sensor. The
remote sensor is a diode-connected transistor, typically
a low-cost, easily mounted 2N3904 NPN type that
replaces conventional thermistors or thermocouples.
The MAX6627/MAX6628 can also measure the die tem-
perature of other ICs, such as microprocessors (µPs) or
microcontrollers (µCs) that contain an on-chip, diode-
connected transistor.
ꢀ Accuracy
±±1° ꢀ(aꢁx ꢂrꢃ( ꢄ1° ≤ T ≤ +±251°, T = +3ꢄ1°
RJ
A
±2ꢅ.1° ꢀ(aꢁx ꢂrꢃ( ꢆ551° ≤ T ≤ +±ꢄꢄ1°,
RJ
ꢄ1° ≤ T ≤ +7ꢄ1°
A
ꢀ ±2ꢆBit + Sign, ꢄꢅꢄ6251° Resꢃlutiꢃn
ꢀ Lꢃw Pꢃwer °ꢃnsu(ptiꢃn
3ꢄµA ꢀtypx ꢀMAX6628x
2ꢄꢄµA ꢀtypx ꢀMAX6627x
Remote accuracy is ±±1C when the temperature of the
remote diode is between 01C and +±251C and the tem-
perature of the MAX6627/MAX6628 is +301C. The tem-
perature is converted to a ±2-bit + sign word with
0.06251C resolution. The architecture of the device is
capable of interpreting data as high as +±451C from
the remote sensor. The MAX6627/MAX6628 tempera-
ture should never exceed +±251C.
ꢀ Operating Te(perature Range ꢀꢆ551° tꢃ +±251°x
ꢀ Measure(ent Te(perature Range, Re(ꢃte
Junctiꢃn ꢀꢆ551° tꢃ +±.51°x
ꢀ ꢄꢅ5s ꢀMAX6627x ꢃr 8s ꢀMAX6628x °ꢃnversiꢃn Rate
ꢀ SPIꢆ°ꢃ(patible Interꢂace
ꢀ +3ꢅꢄV tꢃ +5ꢅ5V Supply Range
ꢀ 8ꢆPin SOT23 Package
These sensors are 3-wire serial interface SPI™ compat-
ible, allowing the MAX6627/MAX6628 to be readily con-
nected to a variety of µCs. The MAX6627/MAX6628 are
read-only devices, simplifying their use in systems
where only temperature data is required.
Orderinꢀ Information
Two conversion rates are available, one that continu-
ously converts data every 0.5s (MAX6627), and one
that converts data every 8s (MAX6628). The slower ver-
sion provides minimal power consumption under all
operating conditions (30µA, typ). Either device can be
read at any time and provide the data from the last con-
version.
PIN-
PACKAGE
TOP
MARK
PART
TEMP. RANGE
MAX6627MKA-T -551C to +1251C 8 SOT23-8
MAX6628MKA-T -551C to +1251C 8 SOT23-8
AAEQ
AAER
ꢁypical Operatinꢀ °ircuit
Both devices operate with supply voltages between
+3.0V and +5.5V, are specified between -551C and
+±251C, and come in the space-saving 8-pin SOT23
package.
+ 3V TO + 5.5V
0.1µF
V
CC
GND
Applications
Hard Disk Drive
MAX6627
MAX6628
Smart Battery Packs
Automotive
SDO
Industrial Control Systems
Notebooks, PCs
2200pF
2200pF
DXP
DXN
µC
CS
SPI is a trademark of Motorola, Inc.
SCK
Pin Configuration appears at end of data sheet.
________________________________________________________________ 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.
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
Continuous Power Dissipation (T = +701C)
A
V
...........................................................................-0.3V to +6V
8-Pin SOT23 (derate 9.7mW/1C above +701C)...........777mW
Operating Temperature Range .........................-551C to +1251C
Junction Temperature......................................................+1501C
Storage Temperature Range.............................-651C to +1501C
Lead Temperature (soldering, 10s)...................................Note 1
CC
SO, SCK, DXP, CS........................................-0.3V to V
+ 0.3V
CC
DXN .......................................................................-0.3V to +0.8V
SO Pin Current Range.........................................-1mA to +50mA
Current Into All Other Pins ..................................................10mA
ESD Protection (Human Body Model)................................2000V
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, 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
(3.0V ≤ V
≤ 5.5V, -551C ≤ T ≤ +1251C, unless otherwise noted. Typical values are at T = +251C, V
= +3.3V, unless otherwise
CC
CC
A
A
noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TEMPERATURE
0°C ≤ T ≤ +125°C, T = +30°C,
RJ
A
-1.0
-2.4
-4.5
-5.5
0.5
1
V
= +3.3V
CC
-55°C ≤ T ≤ +100°C, 0°C ≤ T ≤ +70°C,
RJ
A
+2.4
+4.5
V
= +3.3V
CC
Accuracy
°C
-55°C ≤ T ≤ +145°C, 0°C ≤ T ≤ +70°C,
RJ
A
V
= +3.3V
CC
-55°C ≤ T ≤ +125°C, -55°C ≤ T ≤ +125°C,
RJ
A
+5.5
0.7
V
= +3.3V
CC
Power-Supply Sensitivity
Resolution
0.25
0.0625
0.5
°C/V
°C
MAX6627
MAX6628
Time Between Conversion Starts
t
s
SAMPLE
8
Conversion Time
t
180
3.0
250
320
ms
CONV
POWER SUPPLY
Supply Voltage Range
V
5.5
5
V
CC
I
Shutdown, V
= +0.8V
CC
SD
Supply Current, SCK Idle
µA
I
ADC idle, CS = low
ADC converting
MAX6627
20
IDLE
CONV
I
360
200
30
600
400
50
Average Operating Current
I
µA
V
CC
MAX6628
Power-On Reset (POR)
Threshold
V
, falling edge
CC
1.6
High level
Low level
80
8
100
10
120
12
Current Sourcing for Diode
µA
2
_______________________________________________________________________________________
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
ELECTRICAL CHARACTERISTICS (continued)
(3.0V ≤ V
≤ 5.5V, -551C ≤ T ≤ +1251C, unless otherwise noted. Typical values are at T = +251C, V
= +3.3V, unless otherwise
CC
CC
A
A
noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS (CS, SCK)
0.3 x
Logic Input Low Voltage
V
V
IL
V
CC
1
0.7 x
Logic Input High Voltage
V
V
IH
V
CC
Input Leakage Current
LOGIC OUTPUTS (SO)
Output Low Voltage
I
V
= V
= GND or V
CC
µA
LEAK
CS
SCK
V
I
I
= 1.6mA
0.4
OL
SINK
V
-
CC
Output High Voltage
V
= 1.6mA
SOURCE
V
OH
0.4
TIMING CHARACTERISTICS (Note 4, Figure 2)
Serial Clock Frequency
SCK Pulse Width High
SCK Pulse Width Low
f
5
MHz
ns
SCL
t
100
100
80
CH
t
ns
CL
CS Fall to SCK Rise
t
C
C
C
C
= 10pF
= 10pF
= 10pF
= 10pF
ns
CSS
LOAD
LOAD
LOAD
LOAD
CS Fall to Output Enable
CS Rise to Output Disable
SCK Fall to Output Data Valid
t
80
50
80
ns
DV
t
ns
TR
t
ns
DO
Note 2: T is the temperature of the remote junction.
RJ
Note 3: Temperature error specification applies for a 01C to +701C temperature range for the MAX6627/MAX6628 package.
Note 4: Serial timing characteristics guaranteed by design.
_______________________________________________________________________________________
3
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
ꢁypical Operatinꢀ °haracteristics
(V = +3.3V, T = +251C, unless otherwise noted.)
CC
A
AVERAGE OPERATING CURRENT
vs. SUPPLY VOLTAGE
POWER-ON-RESET THRESHOLD
vs. TEMPERATURE
TEMPERATURE ERROR vs. TEMPERATURE
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
300
3
2
250
200
150
100
50
T
A
= +70°C
T
A
= +25°C
1
MAX6627
MAX6628
0
T
A
= 0°C
-1
-2
MAX6627
0
-3
3.0
3.5
4.0
4.5
5.0
5.5
-55 -30 -5 20 45 70 95 120 145
-55 -30 -5 20 45 70 95 120 145
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE ERROR
vs. DXP/DXN CAPACITANCE
TEMPERATURE ERROR vs.
POWER-SUPPLY NOISE FREQUENCY
RESPONSE TO THERMAL SHOCK
12
10
8
5
4
3
2
1
0
V
= SQUARE WAVE
IN
APPLIED TO V WITH NO
125
100
75
50
25
0
CC
0.1µF CAPACITOR
6
V
IN
= 250mVp-p
4
2
0
0
5000
10,000
15,000
20,000
10 100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
-2
0
2
4
6
8
10 12 14
CAPACITANCE (pF)
TIME (s)
Pin Description
PIN
NAME
FUNCTION
1
GND
Ground
Combined Current Sink and ADC Negative Input for Remote Diode. DXN is normally biased to a diode
voltage above ground.
2
DXN
DXP
3
4
5
Combined Current Source and ADC Positive Input for Remote Diode
Supply Voltage Input. Bypass with a 0.1µF to GND.
SPI Clock Input
V
CC
SCK
Chip Select Input. Pulling CS low initiates an idle state, but the SPI interface is still enabled. A rising edge
of CS initiates the next conversion.
6
CS
7
8
SO
SPI Data Output
N.C.
No Connect. Can be connected to GND for improved thermal conductivity.
4
_______________________________________________________________________________________
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
ing CS low, any conversion in progress is stopped, and
Detailed Description
the rising edge of CS always starts a fresh conversion
The MAX6627/MAX6628 remote digital thermometers
and resets the interface. This permits triggering a con-
report the temperature of a remote sensor. The remote
version at any time so that the power consumption of
sensor is a diode-connected transistor—typically, a
the MAX6627 can be overcome, if needed. Both
low-cost, easily mounted 2N3904 NPN type—that
devices operate with input voltages between +3.0V and
replaces conventional thermistors or thermocouples.
+5.5V and are specified between -551C and +1251C.
The MAX6627/MAX6628 can also measure the die tem-
The MAX6627 and MAX6628 come in space-saving 8-
perature of other ICs, such as µPs or µCs, that contain
pin SOT23 packages.
an on-chip, diode-connected transistor.
AD° °onversion Sequence
The device powers up as a free-running data converter
(Figure 1). The CS pin can be used for conversion con-
trol. The rising edge of CS resets the interface and
starts a conversion. The falling edge of CS stops any
conversion in progress, overriding the latency of the
part. Temperature data from the previous completed
conversion is available for read (Tables 1 and 2). It is
required to maintain CS high for a minimum of 320ms
to complete a conversion.
Remote accuracy is 11C when the temperature of the
remote diode is between 01C and +1251C and the tem-
perature of the MAX6627/MAX6628 is +301C. Data is
available as a 12-bit + sign word with 0.06251C resolu-
tion. The operating range of the device extends from
-551C to +1251C, although the architecture of the
device is capable of interpreting data up to +1451C.
The device itself should never exceed +1251C.
The MAX6627/MAX6628 are designed to work in con-
junction with an external µC or other intelligent device
serving as the master in thermostatic, process-control,
or monitoring applications. The µC is typically a power
management or keyboard controller, generating SPI
serial commands by “bit-banging” GPIO pins.
Idle Mode
Pull CS low to enter idle mode. In idle mode, the ADC is
not converting. The serial interface is still active and
temperature data from the last completed conversion
can still be read.
Two conversion rates are available; the MAX6627 con-
tinuously converts data every 0.5s, and the MAX6628
continuously converts data every 8s. Either device can
be read at any time and provide the data from the last
conversion. The slower version provides minimal power
consumption under all operating conditions. Or, by tak-
Power-On Reset
The POR supply voltage of the MAX6627/MAX6628 is
typically 1.6V. Below this supply voltage, the interface
is inactive and the data register is set to the POR state,
8s
SAMPLE
RATE
0.5s
SAMPLE
RATE
0.25s
CONVERSION
TIME
MAX6627
MAX6628
ADC CONVERTING
ADC IDLE
Figure 1. Free-Running Conversion Time and Rate Relationships
Table 1. Data Output Format
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
MSB
Data
LSB
Data
Sign
Low
High-Z
High-Z
_______________________________________________________________________________________
5
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
t
CSS
CS
SCK
SO
t
DV
t
DO
t
TR
D15
D3
D2
D1
D0
Figure 2. SPI Timing Diagram
Accuracy has been experimentally verified for all of the
devices listed in Table 3. The MAX6627/MAX6628 can
also directly measure the die temperature of CPUs and
other ICs with on-board temperature-sensing diodes.
Table 2. Temperature Data Format
(Two’s Complement)
DIGITAL OUTPUT (BINARY)
TEMPERATURE
(°C)
The transistor must be a small-signal type with a rela-
tively high forward voltage. This ensures that the input
voltage is within the A/D input voltage range. The for-
ward voltage must be greater than 0.25V at 10µA at the
highest expected temperature. The forward voltage
must be less than 0.95V at 100µA at the lowest expect-
ed temperature. The base resistance has to be less
than 100Ω. Tight specification of forward-current gain
(+50 to +150, for example) indicates that the manufac-
turer has good process control and that the devices
have consistent characteristics.
D15–D3
D2
0
D1, D0
XX
150
125
0,1001,0110,0000
0,0111,1101,0000
0,0001,1001,0000
0,0000,0000,0001
0,0000,0000,0000
1,1111,1111,1111
1,1110,0111,0000
1,1100,1001,0000
0
XX
25
0
XX
0.0625
0
0
XX
0
XX
-0.0625
-25
0
XX
0
XX
-55
0
XX
AD° Noise Filterinꢀ
The integrating ADC has inherently good noise rejec-
tion, especially of low-frequency signals such as
60Hz/120Hz power-supply hum. Micropower operation
places constraints on high-frequency noise rejection.
Lay out the PC board carefully with proper external
noise filtering for high-accuracy remote measurements
in electrically noisy environments.
01C. When power is first applied and V
rises above
CC
1.6V (typ), the device starts to convert, although tem-
perature reading is not recommended at V
below 3.0V.
levels
CC
Serial Interface
Figure 2 is the serial interface timing diagram. The data
is latched into the shift register on the falling edge of
the CS signal and then clocked out at the SO pin on the
falling edge of SCK with the most-significant bit (MSB)
first. There are 16 edges of data per frame. The last 2
bits, D0 and D1, are always in high-Z mode. The falling
edge of CS stops any conversion in progress, and the
rising edge of CS always starts a new conversion and
resets the interface. It is required to maintain a 320ms
minimum pulse width of high CS signal before a con-
version starts.
Table 3. SOT23-Type Remote-Sensor
Transistor Manufacturers
MANUFACTURER
Central Semiconductor (USA)
Fairchild Semiconductor (USA)
Motorola (USA)
MODEL
CMPT3904
MMBT3904
MMBT3904
SST3904
Rohm Semiconductor (Japan)
Siemens (Germany)
Applications Information
SMBT3904
Remote-Diode Selection
Temperature accuracy depends upon having a good-
quality, diode-connected, small-signal transistor.
Zetex (England)
FMMT3904CT-ND
Note: Transistors must be diode connected (short the base to
the collector).
6
_______________________________________________________________________________________
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
Filter high-frequency electromagnetic interference
(EMI) at DXP and DXN with an external 2200pF capaci-
tor connected between the two inputs. This capacitor
can be increased to about 3300pF (max), including
cable capacitance. A capacitance higher than 3300pF
introduces errors due to the rise time of the switched-
current source.
ꢁwisted Pair and Shielded °ables
For remote-sensor distances longer than 8in, or in par-
ticularly noisy environments, a twisted pair is recom-
mended. Its practical length is 6ft to 12ft (typ) before
noise becomes a problem, as tested in a noisy elec-
tronics laboratory. For longer distances, the best solu-
tion is a shielded twisted pair like that used for audio
microphones. For example, Belden #8451 works well
for distances up to 100ft in a noisy environment.
Connect the twisted pair to DXP and DXN and the
shield to ground, and leave the shield’s remote end
unterminated. Excess capacitance at DXN or DXP limits
practical remote-sensor distances (see Typical
Operating Characteristics).
P° Board Layout
1) Place the MAX6627/MAX6628 as close as practical
to the remote diode. In a noisy environment, such
as a computer motherboard, this distance can be
4in to 8in, or more, as long as the worst noise
sources (such as CRTs, clock generators, memory
buses, and ISA/PCI buses) are avoided.
For very long cable runs, the cable’s parasitic capaci-
tance often provides noise filtering, so the recommend-
ed 2200pF capacitor can often be removed or reduced
in value. Cable resistance also affects remote-sensor
accuracy. A 1Ω series resistance introduces about
+1/21C error.
2) Do not route the DXP/DXN lines next to the deflec-
tion coils of a CRT. Also, do not route the traces
across a fast memory bus, which can easily intro-
duce +301C error, even with good filtering.
Otherwise, most noise sources are fairly benign.
3) Route the DXP and DXN traces parallel and close to
each other, away from any high-voltage traces such
as +12VDC. Avoid leakage currents from PC board
contamination. A 20MΩ leakage path from DXP to
ground causes approximately +11C error.
GND
10mils
10mils
10mils
DXP
4) Connect guard traces to GND on either side of the
DXP/DXN traces (Figure 3). With guard traces in
place, routing near high-voltage traces is no longer
an issue.
MINIMUM
10mils
DXN
GND
5) Route as few vias and crossunders as possible to
minimize copper/solder thermocouple effects.
6) When introducing a thermocouple, make sure that
both the DXP and the DXN paths have matching
thermocouples. In general, PC board-induced ther-
mocouples are not a serious problem. A copper
solder thermocouple exhibits 3µV/1C, and it takes
approximately 200µV of voltage error at DXP/DXN
to cause a +11C measurement error, so most para-
sitic thermocouple errors are swamped out.
Figure 3. Recommended DXP/DXN PC Traces
Pin °onfiꢀuration
TOP VIEW
7) Use wide traces. Narrow traces are more inductive
and tend to pick up radiated noise. The 10mil
widths and spacings recommended in Figure 3 are
not absolutely necessary (as they offer only a minor
improvement in leakage and noise), but use them
where practical.
GND
DXN
DXP
1
2
3
4
8
7
6
5
N.C.
SO
MAX6627
MAX6628
CS
V
SCK
CC
8) Placing an electrically clean copper ground plane
between the DXP/DXN traces and traces carrying
high-frequency noise signals helps reduce EMI.
SOT23
_______________________________________________________________________________________
7
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
Functional Diaꢀram
V
CC
SI/O
SCK
CS
DXP
DXN
SPI
INTERFACE
12 BIT + SIGN
ADC
°hip Information
TRANSISTOR COUNT: 6241
PROCESS: BiCMOS
8
_______________________________________________________________________________________
Remote ±±1° Accurate Diꢀital ꢁemperature
Sensors with SPI-°ompatible Serial Interface
Packaꢀe 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.
Maxim Inteꢀrated Products, ±20 San Gabriel Drive, Sunnyvale, °A 94086 408-737-7600 _____________________ 9
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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