MAX1617AMEE应用文章市场行情现货热卖使用介绍供应商报价-中国IC网-芯三七

19-4508; Rev 0; 1/99

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MAX617

________________Ge n e ra l De s c rip t io n

____________________________Fe a t u re s

The MAX1617A (patents pending) is a precise digital ther-

mometer that reports the temperature of both a remote

sensor and its own package. The remote sensor is a

diode-connected transistor—typically a low-cost, easily

mounted 2N3904 NPN type—that replaces conventional

thermistors or thermocouples. Remote accuracy is ±3°C

for multiple transistor manufacturers, with no calibration

needed. The remote channel can also measure the die

temperature of other ICs, such as microprocessors, that

contain an on-chip, diode-connected transistor.

♦ Two Channels: Measures Both Remote and Local

Temperatures

♦ No Calibration Required

♦ SMBus 2-Wire Serial Interface

♦ Programmable Under/Overtemperature Alarms

♦ Supports SMBus Alert Response

♦ Supports Manufacturer and Device ID Codes

A

The 2-wire serial interface accepts standard System

Management Bus (SMBus®) Write Byte, Read Byte, Send

Byte, and Receive Byte commands to program the alarm

thresholds and to read temperature data. The data format

is 7 bits plus sign, with each bit corresponding to 1°C, in

two’s complement format. Measurements can be done

automatically and autonomously, with the conversion rate

programmed by the user or programmed to operate in a

single-shot mode. The adjustable rate allows the user to

control the supply-current drain.

♦ Accuracy

±2°C (+60°C to +100°C, local)

±3°C (-40°C to +125°C, local)

±3°C (+60°C to +100°C, remote)

♦ 3µA (typ) Standby Supply Current

♦ 70µA (max) Supply Current in Auto-Convert Mode

♦ +3V to +5.5V Supply Range

♦ Small 16-Pin QSOP Package

The MAX1617A is nearly identical to the popular MAX1617,

but has improved SMBus timing specifications, improved

bus collision immunity, software manufacturer and device

identification available via the serial interface, and a power-

on reset function that can force a reset of the slave address

via the serial interface.

Ord e rin g In fo rm a t io n

PART*

TEMP. RANGE

PIN-PACKAGE

MAX1617AMEE

-55°C to +125°C

16 QSOP

*U.S. and foreign patents pending.

________________________Ap p lic a t io n s

Desktop and Notebook

Computers

Central Office

Telecom Equipment

Smart Battery Packs

LAN Servers

Test and Measurement

Multichip Modules

Industrial Controls

Typ ic a l Op e ra t in g Circ u it

___________________P in Co n fig u ra t io n

3V TO 5.5V

200Ω

0.1µF

TOP VIEW

N.C.

1

2

3

4

5

6

7

8

16 N.C.

V

STBY

CC

10k EACH

V

CC

15 STBY

14 SMBCLK

13 N.C.

MAX1617A

DXP

DXN

N.C.

DXP

CLOCK

DATA

SMBCLK

MAX1617A

SMBDATA

ALERT

12 SMBDATA

11 ALERT

10 ADD0

DXN

INTERRUPT

TO µC

2N3904

ADD1

GND

2200pF

ADD0 ADD1 GND

9

N.C.

QSOP

SMBus is a registered trademark of Intel Corp.

†Patents Pending

________________________________________________________________ Maxim Integrated Products

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

ABSOLUTE MAXIMUM RATINGS

V

CC

to GND..............................................................-0.3V to +6V

Continuous Power Dissipation (T = +70°C)

A

DXP, ADD_ to GND ....................................-0.3V to (V + 0.3V)

QSOP (derate 8.30mW/°C above +70°C).....................667mW

Operating Temperature Range .........................-55°C to +125°C

Junction Temperature ......................................................+150°C

Storage Temperature Range .............................-65°C to +165°C

Lead Temperature (soldering, 10sec) .............................+300°C

CC

DXN to GND ..........................................................-0.3V to +0.8V

SMBCLK, SMBDATA, ALERT, STBY to GND ...........-0.3V to +6V

SMBDATA, ALERT Current .................................-1mA to +50mA

DXN Current .......................................................................±1mA

ESD Protection (SMBCLK, SMBDATA,

ALERT, Human Body Model) ......................................... 4000V

ESD Protection (other pins, Human Body Model)..............2000V

MX617A

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 = +3.3V, T = 0°C to +85°C, unless otherwise noted.)

CC

A

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

ADC AND POWER SUPPLY

Temperature Resolution (Note 1)

Monotonicity guaranteed

= +60°C to +100°C

8

-2

Bits

°C

T

A

2

3

Initial Temperature Error,

Local Diode (Note 2)

T

= 0°C to +85°C

-3

A

T

= +60°C to +100°C

= -55°C to +125°C

-3

3

R

Temperature Error, Remote Diode

(Notes 2 and 3)

°C

T

R

-5

5

T

= +60°C to +100°C

= 0°C to +85°C

-2.5

-3.5

3.0

2.60

2.5

3.5

5.5

2.95

A

Temperature Error, Local Diode

(Notes 1 and 2)

Including long-term drift

T

A

Supply-Voltage Range

V

Undervoltage Lockout Threshold

Undervoltage Lockout Hysteresis

Power-On Reset Threshold

POR Threshold Hysteresis

V

input, disables A/D conversion, rising edge

2.80

50

CC

mV

V

, falling edge

1.0

1.7

50

2.5

10

CC

mV

SMBus static

3

4

Logic inputs

forced to V

or GND

Standby Supply Current

µA

CC

Hardware or software standby,

SMBCLK at 10kHz

Auto-convert mode, average

Average Operating Supply Current measured over 4sec. Logic

0.25 conv/sec

35

70

inputs forced to V or GND. 2.0 conv/sec

CC

120

125

180

Conversion Time

From stop bit to conversion complete (both channels)

Auto-convert mode

94

-25

80

8

156

25

ms

%

Conversion Rate Timing Error

High level

DXP forced to 1.5V

100

10

120

12

Remote-Diode Source Current

µA

Low level

DXN Source Voltage

0.7

160

V

Address Pin Bias Current

ADD0, ADD1; momentary upon power-on reset

µA

2

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Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

ELECTRICAL CHARACTERISTICS (continued)

(V = +3.3V, T = 0°C to +85°C, unless otherwise noted.)

CC

A

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

SMBus INTERFACE

Logic Input High Voltage

Logic Input Low Voltage

Logic Output Low Sink Current

2.2

V

STBY, SMBCLK, SMBDATA; V = 3V to 5.5V

CC

0.8

STBY, SMBCLK, SMBDATA; V = 3V to 5.5V

CC

6

mA

ALERT, SMBDATA forced to 0.4V

ALERT forced to 5.5V

ALERT Output High Leakage

Current

1

µA

Logic Input Current

Logic inputs forced to V or GND

CC

-1

µA

pF

kHz

µs

SMBus Input Capacitance

SMBus Clock Frequency

SMBCLK Clock Low Time

SMBCLK Clock High Time

SMBus Start-Condition Setup Time

SMBCLK, SMBDATA

(Note 4)

5

DC

4.7

4

100

t

, 10% to 10% points

LOW

HIGH

, 90% to 90% points

µs

4.7

µs

SMBus Repeated Start-Condition

Setup Time

t

, 90% to 90% points

SU:STA

500

ns

SMBus Start-Condition Hold Time

SMBus Stop-Condition Setup Time

t

, 10% of SMBDATA to 90% of SMBCLK

, 90% of SMBCLK to 10% of SMBDATA

4

µs

HD:STA

SU:STO

SMBus Data Valid to SMBCLK

Rising-Edge Time

t

, 10% or 90% of SMBDATA to 10% of SMBCLK

250

0

ns

µs

SU:DAT

SMBus Data-Hold Time

(Note 5)

HD:DAT

SMBCLK Falling Edge to SMBus

Data-Valid Time

Master clocking in data

1

ELECTRICAL CHARACTERISTICS

(V = +3.3V, T = -55°C to +125°C, unless otherwise noted.) (Note 6)

CC

A

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

ADC AND POWER SUPPLY

Temperature Resolution (Note 1)

Monotonicity guaranteed

= +60°C to +100°C

8

-2

Bits

°C

T

A

2

3

Initial Temperature Error,

Local Diode (Note 2)

T

= -55°C to +125°C

= +60°C to +100°C

= -55°C to +125°C

-3

A

T

R

-3

3

Temperature Error, Remote Diode

(Notes 2 and 3)

°C

T

R

-5

5

Supply-Voltage Range

Conversion Time

3.0

94

-25

5.5

156

25

V

ms

%

From stop bit to conversion complete (both channels)

Auto-convert mode

125

Conversion Rate Timing Error

_______________________________________________________________________________________

3

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

ELECTRICAL CHARACTERISTICS (continued)

(V = +3.3V, T = -55°C to +125°C, unless otherwise noted.) (Note 6)

CC

A

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

SMBus INTERFACE

V

= 3V

2.2

2.4

CC

Logic Input High Voltage

V

STBY, SMBCLK, SMBDATA

V

CC

= 5.5V

Logic Input Low Voltage

0.8

V

STBY, SMBCLK, SMBDATA; V = 3V to 5.5V

CC

Logic Output Low Sink Current

6

mA

ALERT, SMBDATA forced to 0.4V

ALERT Output High Leakage

Current

MX617A

1

2

µA

ALERT forced to 5.5V

Logic Input Current

Logic inputs forced to V or GND

-2

CC

Note 1: Guaranteed but not 100% tested.

Note 2: Quantization error is not included in specifications for temperature accuracy. For example, if the MAX1617A device temper-

ature is exactly +66.7°C, the ADC may report +66°C, +67°C, or +68°C (due to the quantization error plus the +1/2°C offset

used for rounding up) and still be within the guaranteed ±1°C error limits for the +60°C to +100°C temperature range

(Table 2).

Note 3: A remote diode is any diode-connected transistor from Table 1. T is the junction temperature of the remote diode. See

R

Remote Diode Selection for remote diode forward voltage requirements.

Note 4: The SMBus logic block is a static design that works with clock frequencies down to DC. While slow operation is possible, it

violates the 10kHz minimum clock frequency and SMBus specifications, and may monopolize the bus.

Note 5: Note that a transition must internally provide at least a hold time in order to bridge the undefined region (300ns max) of

SMBCLK’s falling edge.

Note 6: Specifications from -55°C to +125°C are guaranteed by design, not production tested.

__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s

(T = +25°C, unless otherwise noted.)

A

TEMPERATURE ERROR vs.

TEMPERATURE ERROR

POWER-SUPPLY NOISE FREQUENCY

vs. PC BOARD RESISTANCE

vs. REMOTE-DIODE TEMPERATURE

12

9

20

2

1

V

CC

= SQUARE WAVE APPLIED TO

IN

WITH NO 0.1µF V CAPACITOR

CC

10

V

IN

= 250mVp-p

PATH = DXP TO GND

ZETEX FMMT3904

REMOTE DIODE

6

0

V

= 250mVp-p

IN

MOTOROLA MMBT3904

SAMSUNG KST3904

LOCAL DIODE

V = 100mVp-p

IN

3

-10

-1

-2

REMOTE DIODE

RANDOM

SAMPLES

PATH = DXP TO V (5V)

CC

0

-20

50

500

5k

50k 500k 5M 50M

1

3

10

30

100

-50

0

50

100

150

FREQUENCY (Hz)

LEAKAGE RESISTANCE (MΩ)

TEMPERATURE (°C)

4

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Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

____________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )

(T = +25°C, unless otherwise noted.)

A

TEMPERATURE ERROR vs.

COMMON-MODE NOISE FREQUENCY

DIFFERENTIAL-MODE NOISE FREQUENCY

30

10

5

0

V

= SQUARE WAVE

IN

V

IN

= 10mVp-p SQUARE WAVE

AC COUPLED TO DXN

APPLIED TO DXP-DXN

V

IN

= 100mVp-p

20

10

0

V

IN

= 50mVp-p

0

V

IN

= 25mVp-p

V

= 3mVp-p SQUARE WAVE

IN

APPLIED TO DXP-DXN

-5

50

500

5k

50k 500k 5M 50M

50

500

5k

50k 500k 5M 50M

50

500

5k

50k 500k 5M 50M

FREQUENCY (Hz)

STANDBY SUPPLY CURRENT

vs. CLOCK FREQUENCY

TEMPERATURE ERROR vs.

DXP–DXN CAPACITANCE

STANDBY SUPPLY CURRENT

vs. SUPPLY VOLTAGE

35

30

25

20

15

10

5

20

10

0

100

60

20

6

SMBCLK IS

DRIVEN RAIL-TO-RAIL

ADD0, ADD1

= GND

V

CC

= 5V

®

V

CC

= 5V

ADD0, ADD1

= HIGH-Z

V

CC

= 3.3V

3

0

1k

10k

100k

1000k

0

20

40

60

80

100

0

1

2

3

4

5

SMBCLK FREQUENCY (Hz)

DXP–DXN CAPACITANCE (nF)

SUPPLY VOLTAGE (V)

OPERATING SUPPLY CURRENT

vs. CONVERSION RATE

RESPONSE TO THERMAL SHOCK

500

400

300

200

100

0

125

100

75

50

25

0

V

= 5V

CC

AVERAGED MEASUREMENTS

16-QSOP IMMERSED

IN +115°C FLUORINERT BATH

0

0.0625 0.125 0.25 0.5

1

2

4

8

-2

0

2

4

6

8

10

CONVERSION RATE (Hz)

TIME (sec)

Rail-to Rail is a registered trademark of Nippon Motorola, Ltd.

_______________________________________________________________________________________

5

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

P in De s c rip t io n

NAME

FUNCTION

1, 5, 9,

13, 16

N.C.

No Connection. Not internally connected. May be used for PC board trace routing.

Supply Voltage Input, 3V to 5.5V. Bypass to GND with a 0.1µF capacitor. A 200Ω series resistor is recom-

mended but not required for additional noise filtering.

2

3

V

CC

Combined Current Source and A/D Positive Input for Remote-Diode Channel. Do not leave DXP floating;

tie DXP to DXN if no remote diode is used. Place a 2200pF capacitor between DXP and DXN for noise fil-

tering.

MX617A

DXP

Combined Current Sink and A/D Negative Input. DXN is normally biased to a diode voltage above

ground.

4

6

DXN

SMBus Address Select Pin (Table 8). ADD0 and ADD1 are sampled upon power-up. Excess capacitance

(>50pF) at the address pins when floating may cause address-recognition problems.

ADD1

7, 8

10

GND

ADD0

Ground

SMBus Slave Address Select Pin

SMBus Alert (interrupt) Output, Open Drain

SMBus Serial-Data Input/Output, Open Drain

SMBus Serial-Clock Input

11

ALERT

12

SMBDATA

SMBCLK

14

Hardware Standby Input. Temperature and comparison threshold data are retained in standby mode.

Low = standby mode, high = operate mode.

15

STBY

Ge n e ra l De s c rip t io n

The MAX1617A (patents pending) is a temperature

sensor designed to work in conjunction with an external

microcontroller (µC) or other intelligence in thermostat-

ic, process-control, or monitoring applications. The µC

is typically a power-management or keyboard con-

troller, generating SMBus serial commands by “bit-

banging” general-purpose input/output (GPIO) pins or

via a dedicated SMBus interface block.

ADC a n d Mu lt ip le x e r

The ADC is an averaging type that integrates over a

60ms p e riod (e a c h c ha nne l, typic a l) with e xc e lle nt

noise rejection.

The multip le xe r a utoma tic a lly s te e rs b ia s c urre nts

through the remote and local diodes, measures their

forward voltages, and computes their temperatures.

Both channels are automatically converted once the

conversion process has started, either in free-running

or single-shot mode. If one of the two channels is not

used, the device still performs both measurements, and

the user can simply ignore the results of the unused

channel. If the remote diode channel is unused, tie DXP

to DXN rather than leaving the pins open.

Essentially an 8-bit serial analog-to-digital converter

(ADC) with a sophisticated front end, the MAX1617A

contains a switched current source, a multiplexer, an

ADC, an SMBus interface, and associated control logic

(Figure 1). Temperature data from the ADC is loaded

into two data registers, where it is automatically com-

pared with data previously stored in four over/under-

temperature alarm registers.

The DXN input is biased at 0.65V above ground by an

inte rna l d iod e to s e t up the a na log -to-d ig ita l (A/D)

inputs for a differential measurement. The worst-case

DXP–DXN differential input voltage range is 0.25V to

0.95V.

6

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Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Figure 1. Functional Diagram

_______________________________________________________________________________________

7

·

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

Excess resistance in series with the remote diode caus-

es about +1/2°C error per ohm. Likewise, 200µV of off-

set voltage forced on DXP–DXN causes about 1°C error.

Table 1. Remote-Sensor Transistor

Manufacturers

MANUFACTURER

Central Semiconductor (USA)

Motorola (USA)

MODEL NUMBER

A/D Co n ve rs io n S e q u e n c e

If a Start command is written (or generated automatical-

ly in the free-running auto-convert mode), both channels

are converted, and the results of both measurements

are available after the end of conversion. A BUSY status

bit in the status byte shows that the device is actually

performing a new conversion; however, even if the ADC

is b us y, the re s ults of the p re vious c onve rs ion a re

always available.

CMPT3904

MMBT3904

SST3904

National Semiconductor (USA)

Rohm Semiconductor (Japan)

Samsung (Korea)

MX617A

KST3904-TF

SMBT3904

Siemens (Germany)

Re m o t e -Dio d e S e le c t io n

Temperature accuracy depends on having a good-qual-

ity, diode-connected small-signal transistor. Accuracy

has been experimentally verified for all of the devices

listed in Table 1. The MAX1617A can also directly mea-

sure the die temperature of CPUs and other integrated

circuits having on-board temperature-sensing diodes.

Zetex (England)

FMMT3904CT-ND

Note: Transistors must be diode-connected (base shorted to

collector).

Self-heating does not significantly affect measurement

accuracy. Remote-sensor self-heating due to the diode

current source is negligible. For the local diode, the

worst-case error occurs when auto-converting at the

fastest rate and simultaneously sinking maximum cur-

rent at the ALERT output. For example, at an 8Hz rate

and with ALERT sinking 1mA, the typical power dissi-

The transistor must be a small-signal type with a rela-

tively high forward voltage; otherwise, the A/D input

voltage range can be violated. The forward voltage

must be greater than 0.25V at 10µA; check to ensure

this is true at the highest expected temperature. The

forward voltage must be less than 0.95V at 100µA;

check to ensure this is true at the lowest expected tem-

perature. Large power transistors don’t work at all. Also

ensure that the base resistance is less than 100Ω. Tight

specifications for forward-current gain (+50 to +150, for

e xa mp le ) ind ic a te tha t the ma nufa c ture r ha s g ood

process controls and that the devices have consistent

VBE characteristics.

pation is V

· 450µA plus 0.4V · 1mA. Package theta

CC

J-A is about 150°C/W, so with V = 5V and no copper

PC board heatsinking, the resulting temperature rise is:

CC

dT = 2.7mW · 150°C/W = 0.4°C

Even with these contrived circumstances, it is difficult

to introduce significant self-heating errors.

ADC No is e Filt e rin g

The ADC is an integrating type with inherently good

noise rejection, especially of low-frequency signals

such as 60Hz/120Hz power-supply hum. Micropower

operation places constraints on high-frequency noise

rejection; therefore, careful PC board layout and proper

external noise filtering are required for high-accuracy

remote measurements in electrically noisy environ-

ments.

For heatsink mounting, the 500-32BT02-000 thermal

sensor from Fenwal Electronics is a good choice. This

device consists of a diode-connected transistor, an

aluminum plate with screw hole, and twisted-pair cable

(Fenwal Inc., Milford, MA, 508-478-6000).

Th e rm a l Ma s s a n d S e lf-He a t in g

Thermal mass can seriously degrade the MAX1617A’s

effective accuracy. The thermal time constant of the

QSOP-16 package is about 140sec in still air. For the

MAX1617A junction temperature to settle to within +1°C

after a sudden +100°C change requires about five time

constants or 12 minutes. The use of smaller packages

for remote sensors, such as SOT23s, improves the situ-

a tion. Ta ke c a re to a c c ount for the rma l g ra d ie nts

between the heat source and the sensor, and ensure

that stray air currents across the sensor package do

not interfere with measurement accuracy.

High-frequency EMI is best filtered at DXP and DXN

with an external 2200pF capacitor. This value can be

inc re a s e d to a b out 3300p F (ma x), inc lud ing c a b le

capacitance. Higher capacitance than 3300pF intro-

duces errors due to the rise time of the switched cur-

rent source.

Nearly all noise sources tested cause the ADC measure-

ments to be higher than the actual temperature, typically

by +1°C to +10°C, depending on the frequency and

amplitude (see Typical Operating Characteristics).

8

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Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

P C Bo a rd La yo u t

1) Place the MAX1617A as close as practical to the

GND

remote diode. In a noisy environment, such as a

computer motherboard, this distance can be 4 in. to

8 in. (typical) or more as long as the worst noise

sources (such as CRTs, clock generators, memory

buses, and ISA/PCI buses) are avoided.

10 MILS

MINIMUM

10 MILS

DXP

DXN

GND

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-

d uc e + 30°C e rror, e ve n with g ood filte ring .

Otherwise, most noise sources are fairly benign.

Figure 2. Recommended DXP/DXN PC Traces

3) Route the DXP and DXN traces in parallel and in

close proximity to each other, away from any high-

•

Use guard traces flanking DXP and DXN and con-

necting to GND.

voltage traces such as +12V . Leakage currents

DC

Place the noise filter and the 0.1µF V

bypass

CC

from PC board contamination must be dealt with

carefully, since a 20MΩ leakage path from DXP to

ground causes about +1°C error.

capacitors close to the MAX1617A.

Add a 200Ω resistor in series with V for best noise

CC

filtering (see Typical Operating Circuit).

4) Connect guard traces to GND on either side of the

DXP–DXN traces (Figure 2). With guard traces in

place, routing near high-voltage traces is no longer

an issue.

Tw is t e d P a ir a n d S h ie ld e d Ca b le s

For remote-sensor distances longer than 8 in., or in par-

ticularly noisy environments, a twisted pair is recom-

mended. Its practical length is 6 feet to 12 feet (typical)

before noise becomes a problem, as tested in a noisy

electronics laboratory. For longer distances, the best

solution is a shielded twisted pair like that used for audio

microphones. For example, the Belden 8451 works well

for distances up to 100 feet in a noisy environment.

Connect the twisted pair to DXP and DXN and the shield

to GND, and leave the shield’s remote end unterminated.

5) Route through as few vias and crossunders as possi-

ble 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-sol-

d e r the rmoc oup le e xhib its 3µV/°C, a nd it ta ke s

about 200µV of voltage error at DXP–DXN to cause

a +1°C measurement error. So, most parasitic ther-

mocouple errors are swamped out.

Excess capacitance at DX_ limits practical remote sen-

sor distances (see Typical Operating Characteristics).

For very long cable runs, the cable’s parasitic capaci-

tance often provides noise filtering, so the 2200pF

capacitor can often be removed or reduced in value.

7) Use wide traces. Narrow ones are more inductive

a nd te nd to p ic k up ra d ia te d nois e . The 10 mil

wid ths a nd sp a c ing s re c omme nd e d in Figure 2

aren’t absolutely necessary (as they offer only a

minor improvement in leakage and noise), but try to

use them where practical.

Cable resistance also affects remote-sensor accuracy;

1Ω series resistance introduces about +1/2°C error.

Lo w -P o w e r S t a n d b y Mo d e

Standby mode disables the ADC and reduces the sup-

p ly-c urre nt d ra in to le s s tha n 10µA. Ente r s ta nd b y

mode by forcing the STBY pin low or via the RUN/STOP

bit in the configuration byte register. Hardware and

software standby modes behave almost identically: all

data is retained in memory, and the SMB interface is

alive and listening for reads and writes. The only differ-

ence is that in hardware standby mode, the one-shot

command does not initiate a conversion.

8) Keep in mind that copper can’t be used as an EMI

shield, and only ferrous materials, such as steel, work

well. Placing a copper ground plane between the

DXP-DXN traces and traces carrying high-frequency

noise signals does not help reduce EMI.

P C Bo a rd La yo u t Ch e c k lis t

•

Place the MAX1617A close to a remote diode.

Keep traces away from high voltages (+12V bus).

Keep traces away from fast data buses and CRTs.

Use recommended trace widths and spacings.

Place a ground plane under the traces.

Standby mode is not a shutdown mode. With activity on

the SMBus, extra supply current is drawn (see Typical

Operating Characteristics). In software standby mode,

_______________________________________________________________________________________

9

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

the MAX1617A can be forced to perform A/D conver-

sions via the one-shot command, despite the RUN/STOP

bit being high.

S MBu s Dig it a l In t e rfa c e

From a software perspective, the MAX1617A appears as

a set of byte-wide registers that contain temperature

data, alarm threshold values, or control bits. A standard

SMBus 2-wire serial interface is used to read tempera-

ture data and write control bits and alarm threshold data.

Each A/D channel within the device responds to the

same SMBus slave address for normal reads and writes.

Activate hardware standby mode by forcing the STBY

pin low. In a notebook computer, this line may be con-

nected to the system SUSTAT# suspend-state signal.

The STBY pin low state overrides any software conversion

command. If a hardware or software standby command is

received while a conversion is in progress, the conversion

cycle is truncated, and the data from that conversion is not

latched into either temperature reading register. The previ-

ous data is not changed and remains available.

The MAX1617A employs four standard SMBus protocols:

Write Byte, Read Byte, Send Byte, and Receive Byte

(Figure 3). The shorter Receive Byte protocol allows

quicker transfers, provided that the correct data register

was previously selected by a Read Byte instruction. Use

caution with the shorter protocols in multi-master systems,

since a second master could overwrite the command

byte without informing the first master.

MX617A

Supply-current drain during the 125ms conversion peri-

od is always about 450µA. Slowing down the conver-

s ion ra te re d uc e s the a ve ra g e s up p ly c urre nt (s e e

Typical Operating Characteristics). Between conver-

sions, the instantaneous supply current is about 25µA

due to the current consumed by the conversion rate

timer. In standby mode, supply current drops to about

3µA. At very low supply voltages (under the power-on-

reset threshold), the supply current is higher due to the

address pin bias currents. It can be as high as 100µA,

depending on ADD0 and ADD1 settings.

The temperature data format is 7 bits plus sign in two’s

complement form for each channel, with each data bit rep-

resenting 1°C (Table 2), transmitted MSB first. Measure-

ments are offset by +1/2°C to minimize internal rounding

errors; for example, +99.6°C is reported as +100°C.

Writ e Byt e Fo rm a t

S

ADDRESS

WR

ACK

COMMAND

ACK

DATA

ACK

P

7 bits

8 bits

1

Slave Address: equiva-

lent to chip-select line of

a 3-wire interface

Command Byte: selects which

register you are writing to

Data Byte: data goes into the register

s e t b y the c omma nd b yte (to s e t

thresholds, configuration masks, and

sampling rate)

Re a d Byt e Fo rm a t

S

ADDRESS

WR

ACK

COMMAND

ACK

S

ADDRESS

RD

ACK

DATA

///

P

7 bits

8 bits

7 bits

8 bits

Sla ve Ad d re s s : e q uiva -

lent to chip-select line

Command Byte: selects

which register you are

reading from

Slave Address: repeated

due to change in data-

flow direction

Data Byte: reads from

the register set by the

command byte

S e n d Byt e Fo rm a t

Re c e ive Byt e Fo rm a t

S

ADDRESS WR ACK COMMAND ACK

P

S

ADDRESS

RD

ACK DATA

8 bits

///

P

7 bits

8 bits

7 bits

Data Byte: reads data from

the re g is te r c omma nd e d

by the last Read Byte or

Write Byte tra ns mis s ion;

also used for SMBus Alert

Response return address

Command Byte: sends com-

mand with no data, usually

used for one-shot command

S = Start condition

P = Stop condition

Shaded = Slave transmission

/// = Not acknowledged

Figure 3. SMBus Protocols

10 ______________________________________________________________________________________

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Table 2. Data Format (Two’s Complement)

Table 3. Read Format for Alert Response

Address (0001100)

DIGITAL OUTPUT

DATA BITS

ROUNDED

TEMP.

(°C)

TEMP.

(°C)

BIT

NAME

FUNCTION

SIGN

MSB

LSB

7

ADD7

+130.00

+127.00

+126.50

+126.00

+25.25

+0.50

+0.25

0.00

+127

+126

+25

+1

0

1

111

001

000

111

110

100

011

1111

1110

1001

0001

0000

1111

0111

0110

1001

1111

(MSB)

6

5

4

3

2

1

ADD6

ADD5

ADD4

ADD3

ADD2

ADD1

Provide the current MAX1617A

slave address that was latched at

POR (Table 8)

0

1

Logic 1

(LSB)

-0.25

0

-0.50

0

the T

or T

alarms at their POR settings. In

HIGH

LOW

-0.75

-1

applications that are never subjected to 0°C in normal

operation, a 0000 0000 result can be checked to indi-

cate a fault condition in which DXP is accidentally short

-1.00

-1

-25.00

-25.50

-54.75

-55.00

-65.00

-70.00

-25

-26

-55

-65

circuited. Similarly, if DXP is short circuited to V , the

CC

ADC reads +127°C for both remote and local channels,

and the device alarms.

ALERT

In t e rru p t s

The ALERT interrupt output signal is latched and can

only be cleared by reading the Alert Response address.

Interrupts are generated in response to T

and T

HIGH

LOW

comparisons and when the remote diode is disconnect-

ed (for continuity fault detection). The interrupt does not

halt automatic conversions; new temperature data con-

tinues to be available over the SMBus interface after

ALERT is asserted. The interrupt output pin is open-drain

so that devices can share a common interrupt line. The

interrupt rate can never exceed the conversion rate.

Ala rm Th re s h o ld Re g is t e rs

Four registers store alarm threshold data, with high-

temperature (T ) and low-temperature (T ) reg-

is te rs for e a c h A/D c ha nne l. If e ithe r me a s ure d

te mp e ra ture e q ua ls or e xc e e d s the c orre s p ond ing

alarm threshold value, an ALERT interrupt is asserted.

HIGH

LOW

The power-on-reset (POR) state of both T

registers

HIGH

The interface responds to the SMBus Alert Response

address, an interrupt pointer return-address feature

(see Alert Response Address section). Prior to taking

corrective action, always check to ensure that an inter-

rupt is valid by reading the current temperature.

is full scale (0111 1111, or +127°C). The POR state of

both T registers is 1100 1001 or -55°C.

LOW

Dio d e Fa u lt Ala rm

There is a continuity fault detector at DXP that detects

whether the remote diode has an open-circuit condi-

tion. At the beginning of each conversion, the diode

fault is checked, and the status byte is updated. This

fault detector is a simple voltage detector; if DXP rises

Ale rt Re s p o n s e Ad d re s s

The SMBus Alert Response interrupt pointer provides

quick fault identification for simple slave devices that

lack the complex, expensive logic needed to be a bus

master. Upon receiving an ALERT interrupt signal, the

host master can broadcast a Receive Byte transmission

to the Alert Response slave address (0001 100). Then

any slave device that generated an interrupt attempts

to identify itself by putting its own address on the bus

(Table 3).

a b ove V

- 1V (typ ic a l) d ue to the d iod e c urre nt

CC

source, a fault is detected. Note that the diode fault

isn’t checked until a conversion is initiated, so immedi-

ately after power-on reset the status byte indicates no

fault is present, even if the diode path is broken.

If the remote channel is shorted (DXP to DXN or DXP to

GND), the ADC reads 0000 0000 so as not to trip either

______________________________________________________________________________________ 11

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

Table 4. Command-Byte Bit Assignments

REGISTER

COMMAND

POR STATE

FUNCTION

RLTS

RRTE

RSL

00h

01h

02h

03h

04h

05h

06h

07h

08h

09h

0Ah

0Bh

0Ch

0Dh

0Eh

0Fh

0000 0000*

N/A

Read local temperature: returns latest temperature

Read remote temperature: returns latest temperature

Read status byte (flags, busy signal)

Read configuration byte

RCL

0000 0000

0000 0010

0111 1111

1100 1001

0111 1111

1100 1001

N/A

RCRA

RLHN

RLLI

Read conversion rate byte

Read local T

limit

HIGH

LOW

MX617A

RRHI

RRLS

WCA

Read remote T

limit

HIGH

LOW

limit

Write configuration byte

WCRW

WLHO

WLLM

WRHA

WRLN

OSHT

N/A

Write conversion rate byte

N/A

Write local T

limit

HIGH

LOW

N/A

Write remote T

limit

HIGH

LOW

N/A

limit

N/A

One-shot command (use send-byte format)

SPOR

MFGID

DEVID

FCh

FEh

FFh

N/A

Write software POR

0100 1101

00000001

Read manufacturer ID code

Read device ID code

*If the device is in hardware standby mode at POR, both temperature registers read 0°C.

The Alert Response can activate several different slave

devices simultaneously, similar to the I²C™ General

Call. If more than one slave attempts to respond, bus

arbitration rules apply, and the device with the lower

address code wins. The losing device does not gener-

ate an acknowledge and continues to hold the ALERT

line low until serviced (implies that the host interrupt

input is level-sensitive). Successful reading of the alert

response address clears the interrupt latch.

command is ignored. If a one-shot command is received

in auto-convert mode (RUN/STOP bit = low) between con-

versions, a new conversion begins, the conversion rate

timer is reset, and the next automatic conversion takes

place after a full delay elapses.

Co n fig u ra t io n Byt e Fu n c t io n s

The configuration byte register (Table 5) is used to

mask (disable) interrupts and to put the device in soft-

ware standby mode. The lower six bits are internally set

to (XX1111), making them “don’t care” bits. Write zeros

to these bits. This register’s contents can be read back

over the serial interface.

Co m m a n d Byt e Fu n c t io n s

The 8-bit command byte register (Table 4) is the master

index that points to the various other registers within the

MAX1617A. The register’s POR state is 0000 0000, so

that a Receive Byte transmission (a protocol that lacks

the command byte) that occurs immediately after POR

returns the current local temperature data.

S t a t u s Byt e Fu n c t io n s

The status byte register (Table 6) indicates which (if

any) temperature thresholds have been exceeded. This

byte also indicates whether or not the ADC is convert-

ing and whether there is an open circuit in the remote

diode DXP–DXN path. After POR, the normal state of all

the flag bits is zero, assuming none of the alarm condi-

tions are present. The status byte is cleared by any

The one-shot command immediately forces a new conver-

s ion c yc le to b e g in. In s oftwa re s ta nd b y mod e

(RUN/STOP bit = high), a new conversion is begun, after

which the device returns to standby mode. If a conversion

is in progress when a one-shot command is received, the

I²C is a trademark of Phillips Corp.

12 ______________________________________________________________________________________

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Table 5. Configuration-Byte Bit

Assignments

Table 7. Conversion-Rate Control Byte

CONVERSION

RATE

AVERAGE SUPPLY

CURRENT

DATA

POR

BIT

NAME

FUNCTION

(Hz)

(µA typ, at V

= 3.3V)

CC

STATE

00h

01h

02h

03h

04h

05h

06h

07h

0.0625

30

33

35

48

70

Masks all ALERT inter-

rupts when high.

7 (MSB)

MASK

0

0.125

Standby mode control

bit. If high, the device

immediately stops con-

verting and enters stand-

by mode. If low, the

0.25

0.5

1

RUN/

STOP

6

0

2

128

225

425

device converts in either

one-shot or timer mode.

4

8

5–0

RFU

Reserved for future use

08h to

FFh

RFU

—

Table 6. Status-Byte Bit Assignments

BIT

NAME

FUNCTION

Co n ve rs io n Ra t e Byt e

The conversion rate register (Table 7) programs the time

interval between conversions in free-running auto-convert

mode. This variable rate control reduces the supply cur-

rent in portable-equipment applications. The conversion

rate byte’s POR state is 02h (0.25Hz). The MAX1617A

looks only at the 3 LSB bits of this register, so the upper 5

bits are “don’t care” bits, which should be set to zero. The

conversion rate tolerance is ±25% at any rate setting.

7

A high indicates that the ADC is busy

converting.

BUSY

(MSB)

A high indicates that the local high-

temperature alarm has activated.

6

5

4

3

LHIGH*

LLOW*

RHIGH*

RLOW*

A high indicates that the local low-

temperature alarm has activated.

A high indicates that the remote high-

temperature alarm has activated.

Valid A/D conversion results for both channels are avail-

able one total conversion time (125ms nominal, 156ms

maximum) after initiating a conversion, whether conver-

sion is initiated via the RUN/STOP bit, hardware STBY

pin, one-shot command, or initial power-up. Changing the

conversion rate can also affect the delay until new results

are available (Table 8).

A high indicates that the remote low-

temperature alarm has activated.

A high indicates a remote-diode conti-

nuity (open-circuit) fault.

2

1

OPEN*

RFU

Reserved for future use (returns 0)

0

RFU

Reserved for future use (returns 0)

(LSB)

Ma n u fa c t u re r a n d De vic e ID Co d e s

Two ROM registers provide manufacturer and device ID

codes (Table 4). Reading the manufacturer ID returns

4Dh, which is the ASCII code “M” (for Maxim). Reading

the d e vic e ID re turns 01h, ind ic a ting a MAX1617A

d e vic e . If READ WORD 16-b it SMBus p rotoc ol is

employed (rather than the 8-bit READ BYTE), the least

significant byte contains the data and the most signifi-

cant byte contains 00h in both cases.

*These flags stay high until cleared by POR, or until the status

byte register is read.

successful read of the status byte, unless the fault per-

sists. Note that the ALERT interrupt latch is not auto-

matically cleared when the status flag bit is cleared.

When auto-converting, if the T

and T

limits are

HIGH

LOW

close together, it’s possible for both high-temp and low-

temp status bits to be set, depending on the amount of

time between status read operations (especially when

converting at the fastest rate). In these circumstances,

it’s best not to rely on the status bits to indicate rever-

sals in long-term temperature changes and instead use

a current temperature reading to establish the trend

direction.

S la ve Ad d re s s e s

The MAX1617A appears to the SMBus as one device

having a common address for both ADC channels. The

device address can be set to one of nine different val-

ues by pin-strapping ADD0 and ADD1 so that more

than one MAX1617A can reside on the same bus with-

out address conflicts (Table 9).

______________________________________________________________________________________ 13

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

Table 8. RLTS and RRTE Temp Register Update Timing Chart

NEW CONVERSION RATE

(CHANGED VIA WRITE TO

WCRW)

TIME UNTIL RLTS AND RRTE

ARE UPDATED

OPERATING MODE

CONVERSION INITIATED BY:

Auto-Convert

Power-on reset

n/a (0.25Hz)

156ms max

1-shot command, while idling

between automatic conversions

n/a

1-shot command that occurs

during a conversion

When current conversion is

complete (1-shot is ignored)

Auto-Convert

n/a

MX617A

Auto-Convert

Rate timer

STBY pin

0.0625Hz

0.125Hz

0.25Hz

0.5Hz

1Hz

20sec

Auto-Convert

10sec

Auto-Convert

5sec

Auto-Convert

2.5sec

1.25sec

625ms

312.5ms

237.5ms

156ms

Auto-Convert

2Hz

Auto-Convert

4Hz

Auto-Convert

8Hz

Hardware Standby

Software Standby

n/a

RUN/STOP bit

1-shot command

n/a

The address pin states are checked at POR and SPOR

only, and the address data stays latched to reduce qui-

escent supply current due to the bias current needed

for high-Z state detection.

Table 9. Slave Address Decoding (ADD0

and ADD1)

ADD0

GND

ADD1

GND

ADDRESS

0011 000

0011 001

0011 010

0101 001

0101 010

0101 011

1001 100

1001 101

1001 110

The MAX1617A a ls o re s p ond s to the SMBus Ale rt

Re s p ons e s la ve a d d re s s (s e e the Ale rt Re s p ons e

Address section).

GND

High-Z

GND

V

CC

P OR a n d UVLO

The MAX1617A has a volatile memory. To prevent ambig-

uous power-supply conditions from corrupting the data in

memory and causing erratic behavior, a POR voltage

High-Z

GND

High-Z

V

CC

V

CC

GND

detector monitors V and clears the memory if V falls

CC

below 1.7V (typical, see Electrical Characteristics table).

V

CC

High-Z

When power is first applied and V rises above 1.75V

CC

V

CC

V

CC

(typical), the logic blocks begin operating, although reads

Note: High-Z means that the pin is left unconnected and floating.

and writes at V levels below 3V are not recommended.

CC

A second V comparator, the ADC UVLO comparator,

CC

prevents the ADC from converting until there is sufficient

Power-Up Defaults:

headroom (V = 2.8V typical).

CC

•

Interrupt latch is cleared.

The SPOR software POR command can force a power-on

reset of the MAX1617A registers via the serial interface.

Use the SEND BYTE protocol with COMMAND = FCh.

This is most commonly used to reconfigure the slave

address of the MAX1617A “on the fly,” where external

hardware has forced new states at the ADD0 and ADD1

address pins prior to the software POR. The new address

takes effect less than 100µs after the SPOR transmission

stop condition.

Address select pins are sampled.

ADC begins auto-converting at a 0.25Hz rate.

Comma nd b yte is s e t to 00h to fa c ilita te q uic k

remote Receive Byte queries.

•

T

HIGH

and T

registers are set to max and min

LOW

limits, respectively.

14 ______________________________________________________________________________________

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

A

B

C

D

E

F

G

H

I

J

K

L

M

t

HIGH

LOW

SMBCLK

SMBDATA

t

HD:DAT

HD:STA

SU:STA

SU:DAT

t

SU:STO

BUF

A = START CONDITION

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO SLAVE

H = LSB OF DATA CLOCKED INTO SLAVE

I = SLAVE PULLS SMBDATA LINE LOW

J = ACKNOWLEDGE CLOCKED INTO MASTER

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION, DATA EXECUTED BY SLAVE

M = NEW START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

Figure 4. SMBus Write Timing Diagram

A

B

C

D

E

F

G

H

I

J

K

t

HIGH

LOW

SMBCLK

SMBDATA

t

BUF

SU:STA HD:STA

SU:DAT

SU:STO

A = START CONDITION

E = SLAVE PULLS SMBDATA LINE LOW

I = ACKNOWLEDGE CLOCK PULSE

J = STOP CONDITION

K = NEW START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO MASTER

H = LSB OF DATA CLOCKED INTO MASTER

Figure 5. SMBus Read Timing Diagram

______________________________________________________________________________________ 15

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Listing 1. Pseudocode Example

16 ______________________________________________________________________________________

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Listing 1. Pseudocode Example (continued)

Note: Thermal management decisions should be made

based on the latest temperature obtained from the

MAX1617A rather than the value of the Status Byte. The

MAX1617A responds very quickly to changes in its

environment due to its sensitivity and its small thermal

mass. High and low alarm conditions can exist in the

Status Byte due to the MAX1617A correctly reporting

environmental changes around it.

P ro g ra m m in g Ex a m p le :

Clo c k -Th ro t t lin g Co n t ro l fo r CP Us

Listing 1 gives an untested example of pseudocode for

proportional temperature control of Intel mobile CPUs

via a power-management microcontroller. This program

consists of two main parts: an initialization routine and

an interrupt handler. The initialization routine checks for

SMBus c ommunic a tions p rob le ms a nd s e ts up the

MAX1617A c onfig ura tion a nd c onve rs ion ra te . The

interrupt handler responds to ALERT signals by reading

the current temperature and setting a CPU clock duty

factor proportional to that temperature. The relationship

between clock duty and temperature is fixed in a look-

up table contained in the microcontroller code.

______________________________________________________________________________________ 17

Re m o t e /Lo c a l Te m p e ra t u re S e n s o r

w it h S MBu s S e ria l In t e rfa c e

MX617A

Listing 1. Pseudocode Example (continued)

18 ______________________________________________________________________________________

型号:	MAX1617AMEE
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Obsolete
包装说明：	PLASTIC, QSOP-16
Reach Compliance Code：	not_compliant
ECCN代码：	EAR99
HTS代码：	8542.39.00.01
Factory Lead Time：	1 week
风险等级：	5.14
Is Samacsys：	N
最大精度（摄氏度）：	3 Cel
主体宽度：	3.9 mm
主体高度：	1.75 mm
主体长度或直径：	4.9 mm
外壳：	PLASTIC
JESD-609代码：	e0
安装特点：	SURFACE MOUNT
位数：	8
端子数量：	16
最大工作电流：	0.18 mA
最高工作温度：	125 °C
最低工作温度：	-55 °C
输出接口类型：	2-WIRE INTERFACE
封装主体材料：	PLASTIC/EPOXY
封装等效代码：	SSOP16,.25
封装形状/形式：	RECTANGULAR
电源：	3.3 V
传感器/换能器类型：	TEMPERATURE SENSOR,SWITCH/DIGITAL OUTPUT,SERIAL
子类别：	Other Sensors
最大供电电压：	5.5 V
最小供电电压：	3 V
表面贴装：	YES
技术：	CMOS
端子面层：	Tin/Lead (Sn85Pb15)
端接类型：	SOLDER
Base Number Matches：	1

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