ADT7484AARMZ-R7_技术文档

ADT7484A/ADT7486A

Digital Temperature Sensor

with SST Interface

The ADT7484A/ADT7486A are simple digital temperature sensors

for use in PC applications with a Simple Serial Transport (SST)

interface. These devices can monitor their own temperature as well as

the temperature of one (ADT7484A) or two (ADT7486A) remote

sensor diodes. The ADT7484A/ADT7486A are controlled by a single

SST bidirectional data line. The devices are fixed-address SST clients

where the target address is chosen by the state of the two address pins,

ADD0 and ADD1.

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MARKING

DIAGRAMS

8

T7484A

ALYWG

G

SOIC−8

CASE 751

Features

1

• 1 On-Chip Temperature Sensor

1

A

L

Y

W

G

= Assembly Location

= Wafer Lot

= Year

= Work Week

= Pb−Free Package

• 1 or 2 Remote Temperature Sensors

• Simple Serial Transportt (SSTt) Interface Rev 1 Compliant

• These are Pb−Free Devices

8

Applications

T20

AYWG

G

• Personal Computers

• Portable Personal Devices

• Industrial Sensor Nets

MSOP−8

CASE 846AB

1

10

T22

AYWG

G

MSOP−10

CASE 846AC

1

T2x = Specific Device Code

A

Y

W

G

= Assembly Location

= Year

= Work Week

= Pb−Free Package

(Note: Microdot may be in either location)

PIN ASSIGNMENTS

V

1

2

3

4

8

7

6

5

SST

CC

GND

D1+

D1–

ADD0

ADT7484A

RESERVED

ADD1

(Top View)

V

1

2

3

4

5

10 SST

CC

GND

D1+

D1–

D2+

9

8

7

6

ADD0

RESERVED

ADD1

ADT7486A

D2–

(Top View)

ORDERING INFORMATION

See detailed ordering and shipping information in the package

dimensions section on page 11 of this data sheet.

1

Publication Order Number:

December, 2009 − Rev. 4

ADT7484A−86A/D

ADT7484A/ADT7486A

ON−CHIP

TEMPERATURE

SENSOR

LOCAL TEMPERATURE

VALUE REGISTER

SST INTERFACE

SST

A/D

CONVERTER

D1+

D1–

D2+

D2–

ANALOG MUX

(ADT7486A ONLY)

REMOTE TEMPERATURE

VALUE REGISTER

ADD1

ADD0

ADDRESS

SELECTION

ADT7484A/

ADT7486A

OFFSET REGISTERS

RESERVED

V

GND

DD

Figure 1. Functional Block Diagram

ABSOLUTE MAXIMUM RATINGS

Parameter

Rating

Unit

Supply Voltage (V

)

3.6

5.0

20

V

CC

Voltage on Any Other Pin (Including SST Pin)

Input Current at Any Pin

mA

°C

Package Input Current

Maximum Junction Temperature (T max)

150

J

Storage Temperature Range

−65 to +150

Lead Temperature, Soldering

IR Reflow Peak Temperature

260

300

Lead Temperature, Soldering (10 sec)

ESD Rating

1500

V

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

NOTE: This device is ESD sensitive. Use standard ESD precautions when handling.

THERMAL CHARACTERISTICS

Package Type

q

JA

q

JC

Unit

8−Lead MSOP and 8−Lead SOIC NB Packages (ADT7484A)

10−Lead MSOP (ADT7486A)

206

44

°C/W

NOTE:

q

is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages.

JA

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2

ADT7484A/ADT7486A

ADT7484A PIN ASSIGNMENT

Pin No.

Mnemonic

Type

Power supply

Description

1

2

3

4

5

6

7

8

V

CC

3.3 V 10%.

Ground Pin.

GND

D1+

Ground

Analog input

Digital input

Reserved

Positive Connection to Remote Temperature Sensor.

Negative Connection to Remote Temperature Sensor.

SST Address Select.

D1−

ADD1

RESERVED

ADD0

SST

Connect to Ground.

Digital input

Digital input/output

SST Address Select.

SST Bidirectional Data Line.

ADT7486A PIN ASSIGNMENT

Pin No.

Mnemonic

Type

Power supply

Description

1

2

V

CC

3.3 V 10%.

GND

D1+

Ground

Ground Pin.

3

Analog input

Digital input

Digital input/output

Positive Connection to Remote 1 Temperature Sensor.

Negative Connection to Remote 1 Temperature Sensor.

Positive Connection to Remote 2 Temperature Sensor.

Negative Connection to Remote 2 Temperature Sensor.

SST Address Select.

4

D1−

5

D2+

6

D2−

7

ADD1

RESERVED

ADD0

SST

8

Connect to Ground.

9

SST Address Select.

10

SST Bidirectional Data Line.

ELECTRICAL CHARACTERISTICS (T = T

to T

, = V = V

to V

, unless otherwise noted)

A

MIN

MAX

CC

MIN

MAX

Parameter

Conditions

Min

Typ

Max

Unit

Power Supply

Supply Voltage, V

3.0

3.3

2.8

3.8

3.6

5.0

V

CC

Undervoltage Lockout Threshold

Average Operating Supply Current, I

Continuous conversions

mA

DD

Temperature-to-Digital Converter

Local Sensor Accuracy

40°C ≤ T ≤ 70°C, V = 3.3 V 5%

+1.0

1.75

4.0

°C

A

CC

−40°C ≤ T ≤ +100°C

A

Remote Sensor Accuracy

−40°C ≤ T ≤ +125°C;

1.0

D

T = 25°C; V = 3.3 V

A

CC

−40°C ≤ T ≤ +125°C;

+1.0

1.75

4.0

°C

D

−40 ≤ T ≤ 70°C,

A

V

CC

= 3.3 V 5%

−40°C ≤ T ≤ +125°C;

°C

mA

D

−40 ≤ T ≤ +100°C

A

Remote Sensor Source Current

Low level

Mid level

High level

12

80

204

Resolution

0.016

1.5

°C

Series Resistance Cancellation

The ADT7484A and ADT7486A cancel

1.5 kW in series with the remote

thermal diode

kW

1. Guaranteed by design, not production tested.

2. Minimum and maximum bit times are relative to t

defined in the timing negotiation pulse.

BIT

3. Devices compatible with hold time specification as driven by SST originator.

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3

ADT7484A/ADT7486A

ELECTRICAL CHARACTERISTICS (T = T

to T

, = V = V

to V

, unless otherwise noted)

A

MIN

MAX

CC

MIN

MAX

Parameter

Conditions

Min

Typ

Max

Unit

Temperature-to-Digital Converter

Conversion Time (Local Temperature)

(Note 1)

Averaging enabled

12

38

50

ms

Conversion Time (Remote Temperature)

(Note 1)

Total Monitoring Cycle Time (Note 1)

Digital Inputs (ADD0, ADD1)

Input High Voltage, V

2.3

V

IH

Input Low Voltage, V

0.8

1.0

V

IL

Input High Current, I

V

= V

= 0

−1.0

mA

pF

IH

IN

CC

Input Low Current, I

IL

IN

Pin Capacitance

5.0

Digital I/O (SST Pin)

Input High Voltage, V

1.1

V

IH

Input Low Voltage, V

Hysteresis (Note 1)

0.4

IL

Between input switching levels

= 6 mA (maximum)

150

mV

V

Output High Voltage, V

I

1.9

1.0

OH

SOURCE

High Impedance State Leakage, I

Device powered on SST bus;

= 1.1 V, V = 3.3 V

mA

LEAK

V

SST

CC

High Impedance State Leakage, I

Device unpowered on SST bus;

= 1.1 V, V = 0 V

10

mA

V

SST

CC

Signal Noise Immunity, V

Noise glitches from

10 MHz to 100 MHz; width up to 50 ns

300

mV

p-p

NOISE

SST Timing

Bitwise Period, t

0.495

500

ms

BIT

High Level Time for Logic 1, t

(Note 2)

t

defined in speed negotiation

0.6 x t

0.75 x t

0.25 x t

0.8 x t

0.4 x t

0.2 x t

H1

BIT

High Level Time for Logic 0, t

(Note 2)

0.2 x t

ms

H0

BIT

Time to Assert SST High for Logic 1,

BIT

t

SU, HIGH

Hold Time, t

Stop Time, t

(Note 3)

See SST Specification Rev 1.0

0.5 x t

ms

HOLD

BIT−M

Device responding to a constant low

level driven by originator

1.25 x t

2 x t

BIT

STOP

BIT

Time to Respond After a Reset, t

0.4

ms

RESET

Response Time to Speed Negotiation

After Powerup

Time after powerup when device can

participate in speed negotiation

500

ms

1. Guaranteed by design, not production tested.

2. Minimum and maximum bit times are relative to t

defined in the timing negotiation pulse.

BIT

3. Devices compatible with hold time specification as driven by SST originator.

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4

ADT7484A/ADT7486A

TYPICAL CHARACTERISTICS

1.55

1.50

1.45

1.40

1.35

1.30

1.25

1.20

3.56

3.55

3.54

3.53

3.52

3.51

3.50

3.49

3.48

3.47

3.46

3.45

DEV3

DEV2

750Ω (~2mA)

270Ω (~5.2mA)

120Ω (~10.6mA)

DEV1

95

2.6

2.8

3.0

3.2

3.4

3.6

–45

–25

–5

15

35

55

75

115

V

(V)

TEMPERATURE (5C)

CC

Figure 2. SST O/P Level vs. Supply Voltage

Figure 3. Supply Current vs. Temperature

7

6

5

4

1.55

750Ω (~2mA)

1.50

1.45

1.40

1.35

1.30

1.25

1.20

270Ω (~5.2mA)

HI SPEC (V = 3V)

3

2

CC

MEAN (V = 3.3V)

CC

1

120Ω (~10.6mA)

0

LO SPEC (V = 3.6V)

CC

–1

–60 –40 –20

0

20

40

60

80

100 120 140

–50

0

50

100

150

TEMPERATURE (5C)

Figure 4. Local Temperature Error

Figure 5. SST O/P Level vs. Temperature

3.9

3.7

3.5

3.3

3.1

2.9

7

6

5

4

3

2

DEV2

DEV3

DEV1

HI SPEC (V = 3V)

CC

1

MEAN (V = 3.3V)

CC

LO SPEC (V = 3.6V)

CC

–2

2.65

2.85

3.05

3.25

3.45

3.65

–60 –40 –20

0

20

40

60

80

100 120 140

V

(V)

TEMPERATURE (5C)

CC

Figure 6. Supply Current vs. Voltage

Figure 7. Remote Temperature Error

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5

ADT7484A/ADT7486A

TYPICAL CHARACTERISTICS

15

10

5

30

25

20

15

10

5

DEV1_EXT1

DEV1_EXT2

DEV2_EXT1

DEV2_EXT2

DEV3_EXT1

DEV3_EXT2

D+ TO GND

100mV

60mV

ć10

ć15

ć20

ć25

–30

–35

–40

DEV1_EXT1

DEV1_EXT2

DEV2_EXT1

DEV2_EXT2

DEV3_EXT1

DEV3_EXT2

D+ TO V

CC

40mV

0

–5

10k

0

20

40

60

80

100

100k

1M

10M

100M

1G

RESISTANCE (MΩ)

NOISE FREQUENCY (5C)

Figure 8. Remote Temperature Error vs. PCB

Resistance

Figure 9. Temperature Error vs. Common-Mode

Noise Frequency

20

15

10

5

0

–10

–20

–30

EXT2

ć40

EXT1

ć50

125mV

–60

ć70

ć80

–90

0

50mV

−5

–10

10k

100k

1M

10M

100M

1G

0

10

20

30

40

50

POWER SUPPLY NOISE FREQUENCY (Hz)

CAPACITANCE (nF)

Figure 10. Local Temperature Error vs. Power

Supply Noise

Figure 11. Remote Temperature Error vs.

Capacitance Between D1+ and D1−

5

4

3

2

7

40mV

6

5

4

3

1

125mV

0

50mV

20mV

2

–1

1

–2

10mV

1M

–3

10k

0

10k

100k

1M

10M

100M

1G

100k

10M

100M

1G

POWER SUPPLY NOISE FREQUENCY (Hz)

NOISE FREQUENCY (5C)

Figure 12. Temperature Error vs. Differential-Mode

Noise Frequency

Figure 13. Remote Temperature Error vs. Power

Supply Noise

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6

ADT7484A/ADT7486A

Product Description

ADT7486A to distinguish between three input states: high,

low (GND), and floating. The address range for fixed

address, discoverable devices is 0x48 to 0x50.

The ADT7484A is a single remote temperature sensor,

and the ADT7486A is a dual temperature sensor for use in

PC applications. The ADT7484A/ADT7486A accurately

measure local and remote temperature and communicate

over a one-wire Simple Serial Transport (SST) bus interface.

Table 1. ADT7484A/ADT7486A Selectable Addresses

ADD1

ADD0

Address Selected

SST Interface

Low (GND)

Float

Low (GND)

Float

0x48

0x49

0x4A

0x4B

0x4C

0x4D

0x4E

0x4F

0x50

Simple Serial Transport (SST) is a one-wire serial bus and

a communications protocol between components intended

for use in personal computers, personal handheld devices, or

other industrial sensor nets. The ADT7484A/ADT7486A

support SST specification Rev 1.

SST is a licensable bus technology from Analog Devices,

Inc., and Intel Corporation. To inquire about obtaining a

copy of the Simple Serial Transport Specification or an SST

technology license, please email Analog Devices, at

sst_licensing@analog.com or write to Analog Devices,

3550 North First Street, San Jose, CA 95134, Attention: SST

Licensing, M/S B7-24.

High

Low (GND)

Float

High

Low (GND)

Float

High

Command Summary

Table 7 summarizes the commands supported by the

ADT7484A/ADT7486A devices when directed at the target

address selected by the fixed address pins. It contains the

command name, command code (CC), write data length

(WL), read data length (RL), and a brief description.

ADT7484A/ADT7486A Client Address

The client address for the ADT7484A/ADT7486A is

selected using the address pin. The address pin is connected

to a float detection circuit, which allows the ADT7484A/

Table 2. Command Code Summary

Command

Code, CC

Write Length,

WL

Read Length, RL

Description

Ping()

0x00

0x01

0x00

0x02

Shows a nonzero FCS over the header if present.

GetIntTemp()

Shows the temperature of the device’s internal thermal

diode.

GetExt1Temp()

GetExt2Temp()

0x01

0x02

0x01

0x02

Shows the temperature of External Thermal Diode 1.

Shows the temperature of External Thermal Diode 2

(ADT7486A only).

GetAllTemps()

0x00

0x01

0x04 (ADT7484A)

0x06 (ADT7486A)

Shows a 4- or 6-byte block of data (ADT7484A:

GetIntTemp, GetExt1Temp; ADT7486A: GetIntTemp,

GetExt1Temp, GetExt2Temp).

SetExt1Offset()

GetExt1Offset()

0xe0

0x03

0x01

0x00

0x02

Sets the offset used to correct errors in External Diode 1.

Shows the offset that the device is using to correct errors

in External Diode 1.

SetExt2Offset()

GetExt2Offset()

ResetDevice()

0xe1

0xf6

0x03

0x01

0x00

0x02

0x00

Sets the offset used to correct errors in External Diode 2

(ADT7486A only).

Shows the offset that the device is using to correct errors

in External Diode 2 (ADT7486A only).

Functional reset. The ADT7484A/ADT7486A also re-

spond to this command when directed to the Target Ad-

dress 0x00.

GetDIB()

0xf7

0x01

0x08

0x10

Shows information used by SW to identify the device’s

capabilities. Can be in 8- or 16-byte format.

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7

ADT7484A/ADT7486A

Command Code Details

Table 5. Reset Device() Command

Target Address

Write

Length

Read

Length

Reset

Command

FCS

ADT7484A/ADT7486A Device Identifier Block

The GetDIB() command retrieves the device identifier

block (DIB), which provides information to identify the

capabilities of the ADP7484A/ADT7486A. The data

returned can be in 8− or 16−byte format. The full 16−bytes

of DIB is detailed in Table 3. The 8-byte format involves the

first eight bytes described in this table. Byte-sized data is

returned in the respective fields as it appears in Table 3.

Word-sized data, including vendor ID, device ID, and data

values use little endian format, that is, the LSB is returned

first, followed by the MSB.

Device Address

0x01

0x00

0xf6

GetIntTemp()

The ADT7484A/ADT7486A show the local temperature

of the device in response to the GetIntTemp() command. The

data has a little endian, 16-bit, twos complement format.

GetExtTemp()

Prompted by the GetExtTemp() command, the

ADT7484A/ADT7486A show the temperature of the

remote diode in little endian, 16-bit, twos complement

format. The ADT7484A/ADT7486A show 0x8000 in

response to this command if the external diode is an open or

short circuit.

Table 3. DIB Byte Details

Byte

Name

Value

Description

Device

Capabilities

0xc0

Fixed address device

0

GetAllTemps()

Version/

Revision

0x10

Meets Version 1 of the

SST specification

1

The ADT7484A shows the local and remote temperatures

in a 4-byte block of data (internal temperature first, followed

by External Temperature 1) in response to a GetAllTemps()

command. The ADT7486A shows the local and remote

temperatures in a 6-byte block of data (internal temperature

first, followed by External Temperature 1 and External

Temperature 2) in response to this command.

2, 3

Vendor ID

00x11d4

Contains company ID

number in little endian

format

4, 5

Device ID

0x7484

or

0x7486

Contains device ID

number in little endian

format

6

7

Device

0x01

0x00

SST device

Interface

SetExtOffset()

This command sets the offset that the ADT7484A/

ADT7486A will use to correct errors in the external diode.

The offset is set in little endian, 16-bit, twos complement

format. The maximum offset is 128°C with +0.25°C

resolution.

Function

Interface

Reserved

8

Reserved

Revision ID

0x00

0x05

Reserved

9

Reserved

10

11

12

13

14

15

Reserved

GetExtOffset()

Reserved

This command causes the ADT7484A/ADT7486A to

show the offset that they are using to correct errors in the

external diode. The offset value is returned in little endian

format, that is, LSB before MSB.

Reserved

Contains revision ID

Client Device

Address

0x48 to

0x50

Dependent on the state

of the address pins

ADT7484A/ADT7486A Response to Unsupported

Commands

Ping()

A full list of command codes supported by the

ADT7484A/ADT7486A is given in Table 7. The offset

registers (Command Codes 0xe0 and 0xe1) are the only

registers that the user can write to. The other defined

registers are read only. Writing to Register Addresses 0x03

to 0xdf shows a valid FSC, but no action is taken by the

ADT7484A/ADT7486A. The ADT7484A/ADT7486A

show an invalid FSC if the user attempts to write to the

devices between Command Codes 0xe2 to 0xee and no data

is written to the device. These registers are reserved for the

manufacturer’s use only, and no data can be written to the

device via these addresses.

The Ping() command verifies if a device is responding at

a particular address. The ADT7484A/ADT7486A show a

valid nonzero FCS in response to the Ping() command when

correctly addressed.

Table 4. Ping() Command

Target Address

Write Length

Read Length

FCS

Device Address

0x00

ResetDevice()

This command resets the register map and conversion

controller. The reset command can be global or directed at

the client address of the ADT7484A/ADT7486A.

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8

ADT7484A/ADT7486A

Temperature Measurement

calculated using the two DV measurements. This method

BE

The ADT7484A/ADT7486A each have two dedicated

temperature measurement channels: one for measuring the

temperature of an on-chip band gap temperature sensor, and

one for measuring the temperature of a remote diode, usually

located in the CPU or GPU.

can also cancel the effect of series resistance on the

temperature measurement. The resulting DV waveforms

BE

are passed through a 65 kHz low-pass filter to remove noise

and then through a chopper-stabilized amplifier to amplify

and rectify the waveform, producing a dc voltage

The ADT7484A monitors one local and one remote

temperature channel, whereas the ADT7486A monitors one

local and two remote temperature channels. Monitoring of

each of the channels is done in a round-robin sequence. The

monitoring sequence is in the order shown in Table 11.

proportional to DV . The ADC digitizes this voltage, and

BE

a temperature measurement is produced. To reduce the

effects of noise, digital filtering is performed by averaging

the results of 16 measurement cycles for low conversion

rates. Signal conditioning and measurement of the internal

temperature sensor is performed in the same manner.

Table 6. Temperature Monitoring Sequence

V

DD

Channel

Number

Measurement

Conversion

Time (ms)

I

BIAS

I

N1 x I

N2 x I

0

1

2

Local Temperature

12

38

V

OUT+

D+

Remote Temperature 1

TO ADC

REMOTE

SENSING

TRANSISTOR

C1*

D–

BIAS

DIODE

V

OUT–

Remote Temperature 2

(ADT7486A only)

LOW−PASS FILTER

f_C= 65kHz

*CAPACITOR C1 IS OPTIONAL. IT SHOULD ONLY BE USED IN NOISY ENVIRONMENTS.

Temperature Measurement Method

A simple method for measuring temperature is to exploit

the negative temperature coefficient of a diode by measuring

Figure 14. Signal Conditioning for Remote Diode

Temperature Sensors

the base-emitter voltage (V ) of a transistor operated at

BE

Reading Temperature Measurements

constant current. Unfortunately, this technique requires

The temperature measurement command codes are

detailed in Table 12. The temperature data returned is two

bytes in little endian format, that is, LSB before MSB. All

temperatures can be read together by using Command Code

0x00 with a read length of 0x04. The command codes and

returned data are described in Table 12.

calibration to null the effect of the absolute value of V

which varies from device to device.

The technique used in the ADT7484A/ADT7486A

,

BE

measures the change in V when the device is operated at

BE

three different currents.

Figure 16 shows the input signal conditioning used to

measure the output of a remote temperature sensor. This

figure shows the remote sensor as a substrate transistor,

which is provided for temperature monitoring on some

microprocessors, but it could also be a discrete transistor. If

a discrete transistor is used, the collector is not grounded and

should be linked to the base. To prevent ground noise from

interfering with the measurement, the more negative

terminal of the sensor is not referenced to ground, but is

biased above ground by an internal diode at the D1− input.

If the sensor is operating in an extremely noisy environment,

C1 can be added as a noise filter. Its value should not exceed

1000 pF.

Table 7. Temperature Channel Command Codes

Temp

Channel

Command

Code

Returned Data

Internal

0x00

0x01

0x02

0x00

LSB, MSB

External 1

External 2

All Temps

LSB, MSB

Internal LSB, Internal MSB;

External 1 LSB, External 1 MSB;

External 2 LSB, External 2 MSB

To measure DV , the operating current through the

BE

sensor is switched between three related currents. Figure 16

shows N1 x I and N2 x I as different multiples of the current

I. The currents through the temperature diode are switched

between I and N1 x I, giving DV , and then between I and

BE1

N2 x I, giving DV . The temperature can then be

BE2

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ADT7484A/ADT7486A

SST Temperature Sensor Data Format

such as clock generators, data/address buses, and CRTs,

are avoided, this distance can be four to eight inches.

• Route the D1+ and D1− tracks close together in parallel

with grounded guard tracks on each side. Provide a

ground plane under the tracks if possible.

• Use wide tracks to minimize inductance and reduce

noise pickup. A 5 mil track minimum width and

spacing is recommended.

The data for temperature is structured to allow values in

the range of 512°C to be reported. Thus, the temperature

sensor format uses a twos complement, 16-bit binary value

to represent values in this range. This format allows

temperatures to be represented with approximately a

0.016°C resolution.

Table 8. SST Temperature Data Format

5MIL

GND

Temperature (5C)

Twos Complement

MSB

LSB

D+

−125

−80

−40

−20

−5

1110 0000

1110 1100

1111 0110

1111 1011

1111 1110

1111 1111

0000 0000

0000 0001

0000 0100

0000 1010

0001 0100

0001 1111

1100 0000

0000 0000

0011 1110

1100 0000

0000 0000

0100 0000

1100 0010

0000 0000

0100 0000

D–

−1

0

GND

+1

+5

+20

+40

+80

+125

Figure 16. Arrangements of Signal Tracks

• Try to minimize the number of copper/solder joints,

which can cause thermocouple effects. Where

copper/solder joints are used, make sure that they are in

both the D1+ and D1− paths and are at the same

temperature.

• Thermocouple effects should not be a major problem

because 1°C corresponds to about 240 mV, and

thermocouple voltages are about 3 mV/°C of the

temperature difference. Unless there are two

thermocouples with a big temperature differential

between them, thermocouple voltages should be much

less than 200 mV.

Using Discrete Transistors

If a discrete transistor is used, the collector is not grounded

and should be linked to the base. If a PNP transistor is used,

the base is connected to the D1− input and the emitter is

connected to the D1+ input. If an NPN transistor is used, the

emitter is connected to the D1− input and the base is

connected to the D1+ input. Figure 17 shows how to connect

the ADT7484A/ADT7486A to an NPN or PNP transistor for

temperature measurement. To prevent ground noise from

interfering with the measurement, the more negative

terminal of the sensor is not referenced to ground, but is

biased above ground by an internal diode at the D1− input.

• Place a 0.1 mF bypass capacitor close to the device.

• If the distance to the remote sensor is more than eight

inches, the use of a twisted-pair cable is recommended.

This works for distances of about 6 to 12 feet.

ADT7484A/

ADT7486A

ADT7484A/

ADT7486A

2N3904

NPN

D+

D–

D+

D–

• For very long distances (up to 100 feet), use shielded

twisted-pair cables, such as Belden #8451 microphone

cables. Connect the twisted-pair cable to D1+ and D1−

and the shield to GND, close to the device. Leave the

remote end of the shield unconnected to avoid ground

loops.

Because the measurement technique uses switched

current sources, excessive cable and/or filter capacitance

can affect the measurement. When using long cables, the

filter capacitor can be reduced or removed. Cable resistance

can also introduce errors. A 1 W series resistance introduces

about 0.5°C error.

2N3906

PNP

Figure 15. Connections for NPN and PNP Transistors

The ADT7484A/ADT7486A show an external temperature

value of 0x8000 if the external diode is an open or short circuit.

Layout Considerations

Digital boards can be electrically noisy environments.

Take the following precautions to protect the analog inputs

from noise, particularly when measuring the very small

voltages from a remote diode sensor:

• Place the device as close as possible to the remote

sensing diode. Provided that the worst noise sources,

http://onsemi.com

10

ADT7484A/ADT7486A

Temperature Offset

Application Schematics

As CPUs run faster, it is more difficult to avoid high

frequency clocks when running the D1+ and D1− tracks

around a system board. Even when the recommended layout

guidelines are followed, there may still be temperature

errors, attributed to noise being coupled on to the D1+ and

D1− lines. High frequency noise generally has the effect of

producing temperature measurements that are consistently

too high by a specific amount. The ADT7484A/

ADT87486A have a temperature offset command code of

0xe0 through which a desired offset can be set. By doing a

one−time calibration of the system, the offset caused by

system board noise can be calculated and nulled by

specifying it in the ADT7484A/ADT7486A. The offset is

automatically added to every temperature measurement.

The maximum offset is 128°C with 0.25°C resolution. The

offset format is the same as the temperature data format;

16−bit, twos complement notation, as shown in Table 8. The

offset should be programmed in little endian format, that is,

LSB before MSB. The offset value is also returned in little

endian format when read.

V

CC

ADT7484A

SST

1

2

3

4

V

SST

ADD0

D1+ RESERVED

D1– ADD1

8

7

6

5

CC

GND

2N3904 OR CPU

THERMAL DIODE

Figure 17. ADT7484A Typical Application Schematic

V

CC

ADT7486A

1

2

3

4

5

V

10

9

SST

CC

GND

ADD0

2N3904

NPN

D1+ RESERVED

8

D1–

D2+

ADD1

D2–

7

6

CPU

THERMAL

DIODE

Figure 18. ADT7486A Typical Application Schematic

ORDERING INFORMATION

†

Device Order Number*

ADT7484AARZ-REEL

ADT7484AARZ-RL7

ADT7484AARMZ-RL

ADT7484AARMZ-R7

ADT7486AARMZ-RL

ADT7486AARMZ-R7

Branding

Package Option

R−8

Package Type

SOIC−8 NB

Shipping

−

2500 Tape & Reel

1000 Tape & Reel

3000 Tape & Reel

1000 Tape & Reel

3000 Tape & Reel

1000 Tape & Reel

−

R−8

SOIC−8 NB

T20

T22

RM−8

8-Lead MSOP

10-Lead MSOP

RM−8

RM−10

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

*These are Pb−Free packages.

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11

ADT7484A/ADT7486A

PACKAGE DIMENSIONS

SOIC−8 NB

CASE 751−07

ISSUE AJ

NOTES:

1. DIMENSIONING AND TOLERANCING PER

ANSI Y14.5M, 1982.

2. CONTROLLING DIMENSION: MILLIMETER.

3. DIMENSION A AND B DO NOT INCLUDE

MOLD PROTRUSION.

−X−

A

4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)

PER SIDE.

8

5

4

5. DIMENSION D DOES NOT INCLUDE DAMBAR

PROTRUSION. ALLOWABLE DAMBAR

PROTRUSION SHALL BE 0.127 (0.005) TOTAL

IN EXCESS OF THE D DIMENSION AT

MAXIMUM MATERIAL CONDITION.

6. 751−01 THRU 751−06 ARE OBSOLETE. NEW

STANDARD IS 751−07.

S

M

B

0.25 (0.010)

Y

1

K

−Y−

MILLIMETERS

DIM MIN MAX

INCHES

G

MIN

MAX

0.197

0.157

0.069

0.020

A

B

C

D

G

H

J

K

M

N

S

4.80

3.80

1.35

0.33

5.00 0.189

4.00 0.150

1.75 0.053

0.51 0.013

C

N X 45

_

SEATING

PLANE

1.27 BSC

0.050 BSC

−Z−

0.10

0.19

0.40

0

0.25 0.004

0.25 0.007

1.27 0.016

0.010

0.050

8

0.020

0.244

0.10 (0.004)

M

J

H

D

8

0

_

0.25

5.80

0.50 0.010

6.20 0.228

M

S

X

0.25 (0.010)

Z

Y

SOLDERING FOOTPRINT*

1.52

0.060

7.0

4.0

0.275

0.155

0.6

0.024

1.270

0.050

mm

inches

ǒ

Ǔ

SCALE 6:1

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

http://onsemi.com

12

ADT7484A/ADT7486A

PACKAGE DIMENSIONS

MSOP8

CASE 846AB−01

ISSUE O

NOTES:

1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.

2. CONTROLLING DIMENSION: MILLIMETER.

D

3. DIMENSION A DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE

BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED

0.15 (0.006) PER SIDE.

4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION.

INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE.

5. 846A-01 OBSOLETE, NEW STANDARD 846A-02.

H

E

MILLIMETERS

INCHES

NOM

−−

0.003

0.013

0.007

0.118

DIM

A

A1

b

c

D

MIN

−−

0.05

0.25

0.13

2.90

NOM

−−

MAX

MIN

−−

0.002

0.010

0.005

0.114

MAX

0.043

0.006

0.016

0.009

0.122

PIN 1 ID

1.10

0.15

0.40

0.23

3.10

e

0.08

b 8 PL

0.33

M

S

0.08 (0.003)

T B

A

0.18

3.00

E

3.00

0.118

e

L

0.65 BSC

0.55

4.90

0.026 BSC

0.021

0.193

0.40

4.75

0.70

5.05

0.016

0.187

0.028

0.199

SEATING

PLANE

H

E

−T−

A

0.038 (0.0015)

L

A1

c

SOLDERING FOOTPRINT*

1.04

0.38

8X

^8X0.041

0.015

3.20

4.24

5.28

0.126

0.167 0.208

0.65

^6X0.0256

SCALE 8:1

mm

inches

ǒ

Ǔ

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

http://onsemi.com

13

ADT7484A/ADT7486A

PACKAGE DIMENSIONS

MSOP10

CASE 846AC−01

ISSUE O

NOTES:

1. DIMENSIONING AND TOLERANCING PER

ANSI Y14.5M, 1982.

−A−

2. CONTROLLING DIMENSION: MILLIMETER.

3. DIMENSION “A” DOES NOT INCLUDE MOLD

FLASH, PROTRUSIONS OR GATE BURRS.

MOLD FLASH, PROTRUSIONS OR GATE

BURRS SHALL NOT EXCEED 0.15 (0.006)

PER SIDE.

4. DIMENSION “B” DOES NOT INCLUDE

INTERLEAD FLASH OR PROTRUSION.

INTERLEAD FLASH OR PROTRUSION

SHALL NOT EXCEED 0.25 (0.010) PER SIDE.

5. 846B−01 OBSOLETE. NEW STANDARD

846B−02

−B−

K

G

PIN 1 ID

D 8 PL

M

S

A

0.08 (0.003)

T B

MILLIMETERS

INCHES

DIM MIN

MAX

3.10

MIN

MAX

0.122

0.043

0.012

A

B

C

D

G

H

J

2.90

0.95

0.20

0.114

1.10 0.037

0.30 0.008

0.50 BSC

0.020 BSC

0.05

0.10

4.75

0.40

0.15 0.002

0.21 0.004

5.05 0.187

0.70 0.016

0.006

0.008

0.199

0.028

C

0.038 (0.0015)

K

L

−T−

SEATING

PLANE

L

H

J

SOLDERING FOOTPRINT*

1.04

0.041

0.32

0.0126

10X

3.20

4.24

5.28

0.126

0.167 0.208

0.50

mm

inches

ǒ

Ǔ

^8X0.0196

SCALE 8:1

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

ON Semiconductor and

are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice

to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All

operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights

nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications

intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should

Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,

and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death

associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal

Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.

PUBLICATION ORDERING INFORMATION

LITERATURE FULFILLMENT:

N. American Technical Support: 800−282−9855 Toll Free

USA/Canada

Europe, Middle East and Africa Technical Support:

Phone: 421 33 790 2910

Japan Customer Focus Center

Phone: 81−3−5773−3850

ON Semiconductor Website: www.onsemi.com

Order Literature: http://www.onsemi.com/orderlit

Literature Distribution Center for ON Semiconductor

P.O. Box 5163, Denver, Colorado 80217 USA

Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada

Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada

Email: orderlit@onsemi.com

For additional information, please contact your local

Sales Representative

ADT7484A−86A/D

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14


型号：	ADT7484AARMZ-R7
厂家：	ONSEMI
描述：	Digital Temperature Sensor with SST Interface 数字温度传感器与SST接口传感器换能器温度传感器输出元件
文件：	总14页 (文件大小：350K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

ADT7484AARMZ-R7 [ONSEMI]

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