NVT210DMTR2G_技术文档

NVT210

+15C Temperature Monitor

with Series Resistance

Cancellation

The NVT210 is a dual-channel digital thermometer and

undertemperature/overtemperature alarm, intended for use in thermal

management systems. It is register-compatible with the NCT1008 and

NCT72. A feature of the NVT210 is series resistance cancellation,

where up to 1.5 kW (typical) of resistance in series with the temperature

monitoring diode can be automatically cancelled from the temperature

result, allowing noise filtering. The NVT210 has a configurable ALERT

output and an extended, switchable temperature measurement range.

The NVT210 can measure the temperature of a remote thermal diode

accurate to 1°C and the ambient temperature accurate to 3°C. The

temperature measurement range defaults to 0°C to +127°C, compatible

with the NCT1008 and NCT72, but it can be switched to a wider

measurement range of −64°C to +191°C.

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MSOP8

WDFN8

DM SUFFIX

CASE 846A

MT SUFFIX

CASE 511AT

PIN ASSIGNMENT

1

The NVT210 communicates over a 2-wire serial interface,

V

SCLK

DD

2

compatible with system management bus (SMBus/I C) standards. The

D+

D−

SDATA

ALERT/

THERM2

GND

2

default SMBus/I C address of the NVT210 is 0x4C. An NVT210D is

2

available with an SMBus/I C address of 0x4D. This is useful if more

THERM

2

than one NVT210 is used on the same SMBus/I C.

An ALERT output signals when the on-chip or remote temperature is

out of range. The THERM output is a comparator output that allows

on/off control of a cooling fan. The ALERT output can be reconfigured

as a second THERM output, if required.

(Top View)

MARKING DIAGRAMS

The NVT210 has been through Automotive Qualification according to

AEC−Q100 Grade 1 standards.

8

XXXX

AYWG

G

Features

• On-chip and Remote Temperature Sensor

• 0.25°C Resolution/1°C Accuracy on Remote Channel

• 1°C Resolution/1°C Accuracy on Local Channel

• Series Resistance Cancellation Up to 1.5 kW

1

MSOP8

XXXX = Specific Device Code

A

Y

W

G

= Assembly Location

= Year

= Work Week

• Extended, Switchable Temperature Measurement Range

0°C to +127°C (Default) or –64°C to +191°C

= Pb-Free Package

• Register-compatible with NCT1008 and NCT72

(Note: Microdot may be in either location)

2

• 2-wire SMBus/I C Serial Interface with SMBus Alert Support

• Programmable Over/Undertemperature Limits

• Offset Registers for System Calibration

1

VxMG

G

• Up to Two Overtemperature Fail-safe THERM Outputs

• 8-lead MSOP Package and a 2 × 2 WDFN8 Package

• 240 mA Operating Current, 5 mA Standby Current

• Automotive Qualification According to AEC−Q100, Grade 1

• Pb-Free Packages are Available

WDFN8

Vx = Device Code (Where x = C or D)

M

G

= Date Code

= Pb-Free Package

(Note: Microdot may be in either location)

Applications

ORDERING INFORMATION

See detailed ordering and shipping information in the package

dimensions section on page 18 of this data sheet.

• Automotive

• Embedded Systems

1

Publication Order Number:

May, 2015 − Rev. 8

NVT210/D

NVT210

CONVERSION RATE

REGISTER

ADDRESS POINTER

REGISTER

ON-CHIP

TEMPERATURE

SENSOR

LOCAL TEMPERATURE

LOW-LIMIT REGISTER

LOCAL TEMPERATURE

VALUE REGISTER

LOCAL TEMPERATURE

HIGH-LIMIT REGISTER

D+

2

3

ANALOG

MUX

A-TO-D

CONVERTER

RUN/STANDBY

REMOTE TEMPERATURE

LOW-LIMIT REGISTER

D−

BUSY

REMOTE TEMPERATURE

HIGH-LIMIT REGISTER

REMOTE TEMPERATURE

VALUE REGISTER

LOCAL THERM

LIMIT REGISTERS

REMOTE OFFSET

REGISTER

EXTERNAL THERM

LIMIT REGISTERS

CONFIGURATION

REGISTERS

EXTERNAL DIODE OPEN-CIRCUIT

INTERRUPT

MASKING

STATUS REGISTER

NVT210

2

SMBus/I C INTERFACE

1

5

7

8

4

6

V

GND

SDATA

SCLK

THERM

ALERT/THERM2

DD

Figure 1. Functional Block Diagram

Table 1. PIN ASSIGNMENT

Pin No.

Mnemonic

Description

1

2

3

4

5

6

V

Positive Supply, 2.8 V to 3.6 V.

DD

D+

D−

Positive Connection to Remote Temperature Sensor.

Negative Connection to Remote Temperature Sensor.

THERM

GND

Open-drain Output. Can be used as an overtemperature shutdown pin. Requires pullup resistor.

Supply Ground Connection.

ALERT/THERM2

Open-drain Logic Output Used as Interrupt or SMBus ALERT. This can also be configured as a

second THERM output. Requires pullup resistor to V

.

DD

2

7

SDATA

SCLK

Logic Input/Output, SMBus/I C Serial Data. Open-drain Output. Requires pullup resistor.

2

Logic Input, SMBus/I C Serial Clock. Requires pullup resistor.

8

Table 2. ABSOLUTE MAXIMUM RATINGS

Parameter

Rating

Unit

V

Positive Supply Voltage (V ) to GND

−0.3, +3.6

DD

D+

−0.3 to V + 0.3

V

DD

D− to GND

−0.3 to +0.6

−0.3 to +3.6

−1, +50

1

V

SCLK, SDATA, ALERT, THERM

Input Current, SDATA, THERM

Input Current, D−

V

mA

V

ESD Rating, All Pins (Human Body Model)

1,500

Maximum Junction Temperature (T

Storage Temperature Range

)

150

°C

J MAX

−65 to +150

Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality

should not be assumed, damage may occur and reliability may be affected.

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

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2

NVT210

Table 3. THERMAL CHARACTERISTICS (Note 1)

Package Type

q

JA

q

JC

Unit

8-lead MSOP

142

43.74

°C/W

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

JA

Table 4. SMBus/I²C TIMING SPECIFICATIONS (Note 1)

Parameter

Limit at T

and T

Unit

kHz max

ms min

ns max

ns min

ms min

Description

MIN

MAX

f

t

400

−

SCLK

t

1.3

0.6

Clock Low Period, between 10% Points

Clock High Period, between 90% Points

Clock/Data Rise Time

LOW

HIGH

t

R

300

600

100

600

1.3

t

F

Clock/Data Fall Time

t

Start Condition Setup Time

SU; STA

t

(Note 2)

(Note 3)

(Note 4)

Start Condition Hold Time

HD; STA

SU; DAT

SU; STO

Data Setup Time

t

Stop Condition Setup Time

t

Bus Free Time between Stop and Start Conditions

BUF

1. Guaranteed by design, but not production tested.

2. Time from 10% of SDATA to 90% of SCLK.

3. Time for 10% or 90% of SDATA to 10% of SCLK.

4. Time for 90% of SCLK to 10% of SDATA.

t_F

t_LOW

t_{HD; STA}

t_R

SCLK

t_{HD; STA}

t_HIGH

t_{SU; STA}

t_{SU; STO}

t_{SU; DAT}

t_{HD; DAT}

SDATA

t_BUF

STOP START

START

STOP

Figure 2. Serial Bus Timing

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3

NVT210

Table 5. ELECTRICAL CHARACTERISTICS (T = −40°C to +125°C, V = 2.8 V to 3.6 V, unless otherwise noted)

A

DD

Parameter

Conditions

Min

Typ

Max

Unit

Power Supply

Supply Voltage, V

2.8

3.30

3.6

V

DD

Average Operating Supply Current, I

0.0625 Conversions/Sec Rate (Note 1, 2)

Standby Mode

−

240

5.0

350

30

mA

DD

Undervoltage Lockout Threshold

Power-on Reset Threshold

V

DD

input, disables ADC, rising edge

−

2.55

−

V

1.0

−

2.56

Temperature-to-Digital Converter

Local Sensor Accuracy

3.0 V to 3.6 V

0°C ≤ T ≤ +70°C

−

1.0

1.5

°C

A

0°C ≤ T ≤ +85°C

A

Local Sensor Accuracy

2.8 V to 3.6 V

−20°C ≤ T ≤ +110°C

−

2.5

A

Resolution

−

1.0

−

°C

Remote Diode Sensor Accuracy

3.0 V to 3.6 V

0°C ≤ T ≤ +70°C, −55°C ≤ T (Note 3) ≤ +150°C

−

1.0

1.5

2.5

A

D

0°C ≤ T ≤ +85°C, −55°C ≤ T (Note 3) ≤ +150°C

A

D

−40°C ≤ T ≤ +100°C, −55°C ≤ T (Note 3) ≤ +150°C

A

D

Remote Diode Sensor Accuracy

2.8 V to 3.6 V

0°C ≤ T ≤ +70°C, −20°C ≤ T ≤ +110°C

−

1.5

2.25

°C

A

D

−20°C ≤ T ≤ +110°C, T = +40°C

A

D

Resolution

−

0.25

−

°C

mA

Remote Sensor Source Current

High Level (Note 3)

Middle Level (Note 3)

Low Level (Note 3)

−

220

82

13.5

−

Conversion Time

From Stop Bit to Conversion Complete, One-shot

Mode with Averaging Switched On

−

40

52

ms

One-shot Mode with Averaging Off

(that is, Conversion Rate = 16-, 32-, or

64-conversions per Second)

−

6.0

8.0

Maximum Series Resistance Cancelled

Resistance Split Evenly on both the D+ and D– Inputs

−

1.5

−

kW

Open-drain Digital Outputs (THERM, ALERT/THERM2)

Output Low Voltage, V = −6.0 mA

I

−

0.4

1.0

V

OL

OUT

High Level Output Leakage Current, I

V

OUT

= V

DD

0.1

mA

OH

2

SMBus/I C Interface (Note 4 and 5)

Logic Input High Voltage, V SCLK, SDATA

1.4

−

0.8

−

V

IH

Logic Input Low Voltage, V SCLK, SDATA

IL

Hysteresis

−

500

−

mV

mA

pF

SDA Output Low Voltage, V

−

0.4

+1.0

−

OL

Logic Input Current, I , I

−1.0

−

IH IL

2

SMBus/I C Input Capacitance,

SCLK, SDATA

5.0

2

SMBus/I C Clock Frequency

−

25

−

400

64

kHz

ms

2

SMBus/I C Timeout (Note 6)

User Programmable

SCLK Falling Edge to SDATA Valid Time

Master Clocking in Data

1.0

Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product

performance may not be indicated by the Electrical Characteristics if operated under different conditions.

1. See Table 9 for information on other conversion rates.

2. THERM and ALERT pulled to V

.

DD

3. Guaranteed by characterization, but not production tested.

4. Guaranteed by design, but not production tested.

2

5. See SMBus/I C Timing Specifications section for more information.

6. Disabled by default. Detailed procedures to enable it are in the Serial Bus Interface section of the datasheet.

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4

NVT210

TYPICAL PERFORMANCE CHARACTERISTICS

3.5

3.0

2.5

2.0

1.5

3.5

DEV 1

DEV 2

DEV 3

DEV 4

DEV 5

DEV 6

DEV 7

DEV 8

DEV 9

DEV 1

DEV 2

DEV 3

DEV 4

DEV 5

DEV 6

DEV 7

DEV 8

DEV 9

DEV 10

DEV 11

DEV 12

DEV 13

DEV 14

DEV 15

DEV 16

MEAN

DEV 15

DEV 16

HIGH 4

3.0

2.5

2.0

1.5

R

DEV 10

DEV 11

DEV 12

DEV 13

DEV 14

R

HIGH 4

R

LOW 4

R

LOW 4

1.0

0.5

1.0

0.5

0

−0.5

−1.0

−0.5

−1.0

−50

0

50

100

150

−50

0

50

100

150

TEMPERATURE (°C)

Figure 3. Local Temperature Error vs. Temperature

Figure 4. Remote Temperature Error vs. Actual

Temperature

10

0

−2

−4

−6

−8

5

D+ To GND

0

−5

−10

DEV 3

D+ To V

DD

−12

−15

DEV 2

−14

DEV 4

−20

−25

−16

−18

1

10

100

0

5

10

15

20

25

LEAKAGE RESISTANCE (MW)

CAPACITANCE (nF)

Figure 5. Temperature Error vs. D+/D− Leakage

Figure 6. Temperature Error vs. D+/D− Capacitance

Resistance

1000

422

DEV 2BC

900

420

DEV 2BC

800

700

600

418

416

500

DEV 4BC

400

414

DEV 3BC

DEV 4BC

300

200

100

0

DEV 3BC

412

410

408

0.01

0.1

1

10

100

3.0

3.1

3.2

3.3

3.4

3.5

3.6

CONVERSION RATE (Hz)

V

DD

(V)

Figure 7. Operating Supply Current vs.

Conversion Rate

Figure 8. Operating Supply Current vs. Voltage

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5

NVT210

TYPICAL PERFORMANCE CHARACTERISTICS (Cont’d)

4.4

4.2

35

DEV 2BC

DEV 3BC

DEV 4BC

DEV 2

30

4.0

3.8

3.6

3.4

3.2

3.0

25

DEV 3

20

DEV 4

15

10

5

0

1

10

100

1000

3.0

3.1

3.2

3.3

3.4

3.5

3.6

FSCL (kHz)

V

DD

(V)

Figure 9. Standby Supply Current vs. Voltage

Figure 10. Standby Supply Current vs. Clock

Frequency

80

70

25

100 mV

20

60

100 mV

50

40

15

30

10

50 mV

20

20 mV

10

5

20 mV

0

−10

0

100

200

300

400

500

600

0

100

200

300

400

500

600

NOISE FREQUENCY (MHz)

Figure 11. Temperature Error vs. Common-mode

Noise Frequency

Figure 12. Temperature Error vs. Differential-mode

Noise Frequency

60

50

40

30

20

10

0

500

1000

1500

2000

SERIES RESISTANCE (W)

Figure 13. Temperature Error vs. Series Resistance

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6

NVT210

Theory of Operation

Temperature Measurement Method

The NVT210 is a local and remote temperature sensor and

over/under temperature alarm, with the added ability to

automatically cancel the effect of 1.5 kW (typical) of

resistance in series with the temperature monitoring diode.

When the NVT210 is operating normally, the on-board ADC

operates in a free running mode. The analog input

multiplexer alternately selects either the on-chip

temperature sensor to measure its local temperature or the

remote temperature sensor. The ADC digitizes these signals

and the results are stored in the local and remote temperature

value registers.

The local and remote measurement results are compared

with the corresponding high, low, and THERM temperature

limits, stored in eight on-chip registers. Out-of-limit

comparisons generate flags that are stored in the status

register. A result that exceeds the high temperature limit or

the low temperature limit causes the ALERT output to

assert. The ALERT output also asserts if an external diode

fault is detected. Exceeding the THERM temperature limits

causes the THERM output to assert low. The ALERT output

can be reprogrammed as a second THERM output.

A simple method of measuring temperature is to exploit

the negative temperature coefficient of a diode, measuring

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

BE

constant current. However, this technique requires

calibration to null the effect of the absolute value of V

which varies from device to device.

,

BE

The technique used in the NVT210 measures the change

in V when the device operates at three different currents.

BE

Previous devices used only two operating currents, but it is

the use of a third current that allows automatic cancellation

of resistances in series with the external temperature sensor.

Figure 14 shows the input signal conditioning used to

measure the output of an external temperature sensor. This

figure shows the external sensor as a substrate transistor, but

it can equally be a discrete transistor. If a discrete transistor

is used, the collector is not grounded but is linked to the base.

To prevent ground noise 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 D− input. C1 may be added as a noise filter

(a recommended maximum value of 1,000 pF). However, a

better option in noisy environments is to add a filter, as

described in the Noise Filtering section. See the Layout

Considerations section for more information on C1.

The limit registers are programmed and the device

2

controlled and configured via the serial SMBus/I C. The

contents of any register are also read back via the

2

SMBus/I C.

To measure DV , the operating current through the

BE

Control and configuration functions consist of switching

the device between normal operation and standby mode,

selecting the temperature measurement range, masking or

enabling the ALERT output, switching Pin 6 between

ALERT and THERM2, and selecting the conversion rate.

sensor is switched among three related currents. As shown

in Figure 14, N1 × I and N2 × I are different multiples of the

current, I. The currents through the temperature diode are

switched between I and N1 × I, giving DV ; and then

BE1

between I and N2 × I, giving DV . The temperature is

BE2

then calculated using the two DV measurements. This

BE

Series Resistance Cancellation

method also cancels the effect of any series resistance on the

temperature measurement.

Parasitic resistance to the D+ and D− inputs to the

NVT210, seen in series with the remote diode, is caused by

a variety of factors, including PCB track resistance and track

length. This series resistance appears as a temperature offset

in the remote sensor’s temperature measurement. This error

typically causes a 0.5°C offset per ohm of parasitic

resistance in series with the remote diode.

The NVT210 automatically cancels the effect of this

series resistance on the temperature reading, giving a more

accurate result, without the need for user characterization of

this resistance. The NVT210 is designed to automatically

cancel typically up to 1.5 kW of resistance. By using an

advanced temperature measurement method, this process is

transparent to the user. This feature permits resistances to be

added to the sensor path to produce a filter, allowing the part

to be used in noisy environments. See the section on Noise

Filtering for more details.

The resulting DV waveforms are passed through a

BE

65 kHz low-pass filter to remove noise and then to a

chopper-stabilized amplifier. This amplifies and rectifies the

waveform to produce a dc voltage proportional to DV

.

BE

The ADC digitizes this voltage producing a temperature

measurement. To reduce the effects of noise, digital filtering

is performed by averaging the results of 16 measurement

cycles for low conversion rates. At rates of 16-, 32-, and

64-conversions/second, no digital averaging occurs.

Signal conditioning and measurement of the internal

temperature sensor are performed in the same manner.

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7

NVT210

V

DD

I

N1 × I

N2 × I

I

BIAS

D+

C1*

D−

V

OUT+

REMOTE

SENSING

TRANSISTOR

To ADC

V

OUT−

BIAS

DIODE

LOW-PASS FILTER

= 65 kHz

f

C

*CAPACITOR C1 IS OPTIONAL. IT IS ONLY NECESSARY IN NOISY ENVIRONMENTS. C1 = 1,000 pF MAX.

Figure 14. Input Signal Conditioning

Temperature Measurement Results

The extended temperature range is selected by setting

Bit 2 of the configuration register to 1. The temperature

range is 0°C to 127°C when Bit 2 equals 0. A valid result is

available in the next measurement cycle after changing the

temperature range.

The results of the local and remote temperature

measurements are stored in the local and remote temperature

value registers and compared with limits programmed into

the local and remote high and low limit registers.

The local temperature value is in Register 0x00 and has a

resolution of 1°C. The external temperature value is stored

in two registers, with the upper byte in Register 0x01 and the

lower byte in Register 0x10. Only the two MSBs in the

external temperature low byte are used giving the external

temperature measurement a resolution of 0.25°C. Table 6

lists the data format for the external temperature low byte.

In extended temperature mode, the upper and lower

temperature that can be measured by the NVT210 is limited

by the remote diode selection. The temperature registers can

have values from −64°C to +191°C. However, most

temperature sensing diodes have a maximum temperature

range of −55°C to +150°C. Above +150°C, they may lose

their semiconductor characteristics and approximate

conductors instead. This results in a diode short. In this case,

a read of the temperature result register gives the last good

temperature measurement. Therefore, the temperature

measurement on the external channel may not be accurate

for temperatures that are outside the operating range of the

remote sensor.

It should be noted that although both local and remote

temperature measurements can be made while the part is in

extended temperature mode, the NVT210 itself should not

be exposed to temperatures greater than those specified in

the absolute maximum ratings section. Further, the device is

only guaranteed to operate as specified at ambient

temperatures from −40°C to +120°C.

Table 6. EXTENDED TEMPERATURE RESOLUTION

(REMOTE TEMPERATURE LOW BYTE)

Remote Temperature

Low Byte

0 000 0000

0 100 0000

1 000 0000

1 100 0000

Extended Resolution

0.00°C

0.25°C

0.50°C

0.75°C

When reading the full external temperature value, read the

LSB first. This causes the MSB to be locked (that is, the

ADC does not write to it) until it is read. This feature ensures

that the results read back from the two registers come from

the same measurement.

Temperature Data Format

The NVT210 has two temperature data formats. When the

temperature measurement range is from 0°C to 127°C

(default), the temperature data format for both internal and

external temperature results is binary. When the

measurement range is in extended mode, an offset binary

data format is used for both internal and external results.

Temperature values are offset by 64°C in the offset binary

data format. Examples of temperatures in both data formats

are shown in Table 7.

Temperature Measurement Range

The temperature measurement range for both internal and

external measurements is, by default, 0°C to +127°C.

However, the NVT210 can be operated using an extended

temperature range. The extended measurement range is

−64°C to +191°C. Therefore, the NVT210 can be used to

measure the full temperature range of an external diode,

from −55°C to +150°C.

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8

NVT210

register. It is to this register address that the second byte of

a write operation is written, or to which a subsequent read

operation is performed.

The power-on default value of the address pointer register

is 0x00. Therefore, if a read operation is performed

immediately after power-on, without first writing to the

address pointer, the value of the local temperature is returned

because its register address is 0x00.

Table 7. TEMPERATURE DATA FORMAT

(TEMPERATURE HIGH BYTE)

Offset Binary

(Note 1)

Temperature

Binary

–55°C

0 000 0000

(Note 2)

0 000 1001

0°C

0 000 0000

0 000 0001

0 000 1010

0 001 1001

0 011 0010

0 100 1011

0 110 0100

0 111 1101

0 111 1111

0 100 0000

0 100 0001

0 100 1010

0 101 1001

0 111 0010

1 000 1011

1 010 0100

1 011 1101

1 011 1111

1 101 0110

+1°C

Temperature Value Registers

+10°C

+25°C

+50°C

+75°C

+100°C

+125°C

+127°C

+150°C

The NVT210 has three registers to store the results of local

and remote temperature measurements. These registers can

only be written to by the ADC and can be read by the user

2

over the SMBus/I C. The local temperature value register is

at Address 0x00.

The external temperature value high byte register is at

Address 0x01, with the low byte register at Address 0x10.

The power-on default for all three registers is 0x00.

0 111 1111

(Note 3)

Configuration Register

1. Offset binary scale temperature values are offset by 64°C.

2. Binary scale temperature measurement returns 0°C for all

temperatures < 0°C.

The configuration register is Address 0x03 at read and

Address 0x09 at write. Its power-on default is 0x00. Only

four bits of the configuration register are used. Bit 0, Bit 1,

Bit 3, and Bit 4 are reserved; the user does not write to them.

Bit 7 of the configuration register masks the ALERT

output. If Bit 7 is 0, the ALERT output is enabled. This is the

power-on default. If Bit 7 is set to 1, the ALERT output is

disabled. This applies only if Pin 6 is configured as ALERT.

If Pin 6 is configured as THERM2, then the value of Bit 7

has no effect.

3. Binary scale temperature measurement returns 127°C for all

temperatures > 127°C.

The user can switch between measurement ranges at any

time. Switching the range likewise switches the data format.

The next temperature result following the switching is

reported back to the register in the new format. However, the

contents of the limit registers do not change. It is up to the

user to ensure that when the data format changes, the limit

registers are reprogrammed as necessary. More information

on this is found in the Limit Registers section.

If Bit 6 is set to 0, which is power-on default, the device

is in operating mode with ADC converting. If Bit 6 is set to

1, the device is in standby mode and the ADC does not

2

convert. The SMBus/I C does, however, remain active in

NVT210 Registers

standby mode; therefore, values can be read from or written

to the NVT210 via the SMBus. The ALERT and THERM

outputs are also active in standby mode. Changes made to

the registers in standby mode that affect the THERM or

ALERT outputs cause these signals to be updated.

Bit 5 determines the configuration of Pin 6 on the

NVT210. If Bit 5 is 0 (default), then Pin 6 is configured as

an ALERT output. If Bit 5 is 1, then Pin 6 is configured as

a THERM2 output. Bit 7, the ALERT mask bit, is only

active when Pin 6 is configured as an ALERT output. If

Pin 6 is set up as a THERM2 output, then Bit 7 has no effect.

Bit 2 sets the temperature measurement range. If Bit 2 is

0 (default value), the temperature measurement range is set

between 0°C to +127°C. Setting Bit 2 to 1 sets the

measurement range to the extended temperature range

(−64°C to +191°C).

The NVT210 contains 22, 8-bit registers in total. These

registers store the results of remote and local temperature

measurements, high and low temperature limits, and

configure and control the device. See the Address Pointer

Register section through the Consecutive ALERT Register

section of this data sheet for more information on the

NVT210 registers. Additional details are shown in Table 8

through Table 12. The entire register map is available in

Table 13.

Address Pointer Register

The address pointer register itself does not have, nor does

it require, an address because the first byte of every write

operation is automatically written to this register. The data

in this first byte always contains the address of another

register on the NVT210 that is stored in the address pointer

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9

NVT210

and lower byte for each limit. There is also a THERM

Table 8. CONFIGURATION REGISTER BIT

ASSIGNMENTS

hysteresis register. All limit registers can be written to, and

2

read back over, the SMBus/I C. See Table 13 for details of

Power-on

Default

the limit register addresses and their power-on default

values.

Bit

Name

MASK1

Function

7

0 = ALERT Enabled

1 = ALERT Masked

0

When Pin 6 is configured as an ALERT output, the high

limit registers perform a > comparison, while the low limit

registers perform a ≤ comparison. For example, if the high

limit register is programmed with 80°C, then measuring

81°C results in an out-of-limit condition, setting a flag in the

status register. If the low limit register is programmed with

0°C, measuring 0°C or lower results in an out-of-limit

condition.

Exceeding either the local or remote THERM limit asserts

THERM low. When Pin 6 is configured as THERM2,

exceeding either the local or remote high limit asserts

THERM2 low. A default hysteresis value of 10°C is

provided that applies to both THERM channels. This

hysteresis value can be reprogrammed to any value after

powerup (Register Address 0x21).

It is important to remember that the temperature limits

data format is the same as the temperature measurement data

format. Therefore, if the temperature measurement uses

default binary, then the temperature limits also use the

binary scale. If the temperature measurement scale is

switched, however, the temperature limits do not

automatically switch. The user must reprogram the limit

registers to the desired value in the correct data format. For

example, if the remote low limit is set at 10°C with the

default binary scale, the limit register value is 0000 1010b.

If the scale is switched to offset binary, the value in the low

temperature limit register needs to be reprogrammed to

0100 1010b.

6

5

RUN/STOP

0 = Run

1 = Standby

ALERT/

THERM2

0 = ALERT

1 = THERM2

4, 3

2

Reserved

0

Temperature

Range Select

0 = 0°C to 127°C

1 = Extended Range

1, 0

Reserved

0

Conversion Rate Register

The conversion rate register is Address 0x04 at read and

Address 0x0A at write. The lowest four bits of this register

are used to program the conversion rate by dividing the

internal oscillator clock by 1, 2, 4, 8, 16, 32, 64, 128, 256,

512, or 1024 to give conversion times from 15.5 ms

(Code 0x0A) to 16 seconds (Code 0x00). For example, a

conversion rate of eight conversions per second means that

beginning at 125 ms intervals, the device performs a

conversion on the internal and the external temperature

channels.

The conversion rate register can be written to and read

2

back over the SMBus/I C. The higher four bits of this

register are unused and must be set to 0. The default value

of this register is 0x08, giving a rate of 16 conversions per

second. Use of slower conversion times greatly reduces the

device power consumption.

Table 9. CONVERSION RATE REGISTER CODES

Status Register

The status register is a read-only register at Address 0x02.

It contains status information for the NVT210.

When Bit 7 of the status register is high, it indicates that

the ADC is busy converting. The other bits in this register

flag the out-of-limit temperature measurements (Bit 6 to

Bit 3, and Bit 1 to Bit 0) and the remote sensor open circuit

(Bit 2).

Code

0x00

Conversion/Second

Time

16 s

0.0625

0x01

0.125

8 s

0x02

0.25

4 s

0x03

0.5

2 s

0x04

1

1 s

If Pin 6 is configured as an ALERT output, the following

applies: If the local temperature measurement exceeds its

limits, Bit 6 (high limit) or Bit 5 (low limit) of the status

register asserts to flag this condition. If the remote

temperature measurement exceeds its limits, then Bit 4

(high limit) or Bit 3 (low limit) asserts. Bit 2 asserts to flag

an open circuit condition on the remote sensor. These five

flags are NOR’ed together, so if any of them is high, the

ALERT interrupt latch is set and the ALERT output goes

low.

0x05

2

500 ms

250 ms

125 ms

62.5 ms

31.25 ms

15.5 ms

−

0x06

4

0x07

8

16

0x08

0x09

32

0x0A

64

0x0B to 0xFF

Reserved

Limit Registers

Reading the status register clears the five flags, Bit 6 to

Bit 2, provided the error conditions causing the flags to be

set have gone away. A flag bit can be reset only if the

The NVT210 has eight limit registers: high, low, and

THERM temperature limits for both local and remote

temperature measurements. The remote temperature high

and low limits span two registers each, to contain an upper

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10

NVT210

corresponding value register contains an in-limit

measurement or if the sensor is good.

minimum, programmable offset is −128°C, and the

maximum is +127.75°C. The value in the offset register is

added to, or subtracted from, the measured value of the

remote temperature.

The offset register powers up with a default value of 0°C

and has no effect unless the user writes a different value to

it.

The ALERT interrupt latch is not reset by reading the

status register. It resets when the ALERT output has been

serviced by the master reading the device address, provided

the error condition has gone away and the status register flag

bits are reset.

When Flag 1 and/or Flag 0 are set, the THERM output

goes low to indicate that the temperature measurements are

outside the programmed limits. The THERM output does

not need to be reset, unlike the ALERT output. Once the

measurements are within the limits, the corresponding status

register bits are automatically reset and the THERM output

goes high. The user may add hysteresis by programming

Register 0x21. The THERM output is reset only when the

temperature falls to limit value minus the hysteresis value.

When Pin 6 is configured as THERM2, only the high

temperature limits are relevant. If Flag 6 and/or Flag 4 are

set, the THERM2 output goes low to indicate that the

temperature measurements are outside the programmed

limits. Flag 5 and Flag 3 have no effect on THERM2. The

behavior of THERM2 is otherwise the same as THERM.

Table 11. SAMPLE OFFSET REGISTER CODES

Offset Value

−128°C

−4°C

0x11

0x12

1000 0000

1111 1100

1111 1111

0000 0000

0000 0001

0000 0100

0111 1111

00 00 0000

00 000000

10 00 0000

00 00 0000

01 00 0000

00 00 0000

11 00 0000

−1°C

−0.25°C

0°C

+0.25°C

+1°C

+4°C

+127.75°C

One-shot Register

The one-shot register is used to initiate a conversion and

comparison cycle when the NVT210 is in standby mode,

after which the device returns to standby. Writing to the

one-shot register address (0x0F) causes the NVT210 to

perform a conversion and comparison on both the internal

and the external temperature channels. This is not a data

register as such, and it is the write operation to Address 0x0F

that causes the one-shot conversion. The data written to this

address is irrelevant and is not stored.

Table 10. STATUS REGISTER BIT ASSIGNMENTS

Bit

7

Name

Function

BUSY

1 when ADC is Converting

6

LHIGH

(Note 1)

1 when Local High Temperature Limit is

Tripped

5

4

3

2

LLOW

(Note 1)

1 when Local Low Temperature Limit is

Tripped

RHIGH

(Note 1)

1 when Remote High Temperature Limit

is Tripped

Consecutive ALERT Register

RLOW

(Note 1)

1 when Remote Low Temperature Limit

is Tripped

The value written to this register determines how many

out-of-limit measurements must occur before an ALERT is

generated. The default value is that one out-of-limit

measurement generates an ALERT. The maximum value

that can be chosen is 4. The purpose of this register is to

allow the user to perform some filtering of the output. This

is particularly useful at the fastest three conversion rates,

where no averaging takes place. This register is at

Address 0x22.

OPEN

(Note 1)

1 when Remote Sensor is an Open

Circuit

1

0

RTHRM

LTHRM

1 when Remote THERM Limit is Tripped

1 when Local THERM Limit is Tripped

1. These flags stay high until the status register is read or they are

reset by POR unless Pin 6 is configured as THERM2. Then, only

Bit 2 remains high until the status register is read or is reset by

POR.

Offset Register

Table 12. CONSECUTIVE ALERT REGISTER CODES

Number of Out-of-limit

Offset errors can be introduced into the remote

temperature measurement by clock noise or when the

thermal diode is located away from the hot spot. To achieve

the specified accuracy on this channel, these offsets must be

removed.

The offset value is stored as a 10-bit, twos complement

value in Register 0x11 (high byte) and Register 0x12 (low

byte, left justified). Only the upper two bits of Register 0x12

are used. The MSB of Register 0x11 is the sign bit. The

Measurements Required

Register Value

yxxx 000x

yxxx 001x

yxxx 011x

1

2

3

4

yxxx 111x

NOTE: x = don’t care bits, and y = SMBus timeout bit.

Default = 0. See SMBus section for more information.

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NVT210

Table 13. LIST OF REGISTERS

Read Address (Hex)

Write Address (Hex)

Name

Power-on Default

Undefined

Not Applicable

Address Pointer

00

Not Applicable

Local Temperature Value

External Temperature Value High Byte

Status

0000 0000 (0x00)

01

Not Applicable

0000 0000 (0x00)

02

Not Applicable

Undefined

03

09

Configuration

0000 0000 (0x00)

04

0A

Conversion Rate

0000 1000 (0x08)

05

0B

Local Temperature High Limit

Local Temperature Low Limit

External Temperature High Limit High Byte

External Temperature Low Limit High Byte

One-shot

0101 0101 (0x55) (85°C)

0000 0000 (0x00) (0°C)

0101 0101 (0x55) (85°C)

0000 0000 (0x00) (0°C)

06

0C

07

0D

08

0E

Not Applicable

0F (Note 1)

10

11

12

13

14

19

20

21

22

FE

Not Applicable

External Temperature Value Low Byte

External Temperature Offset High Byte

External Temperature Offset Low Byte

External Temperature High Limit Low Byte

External Temperature Low Limit Low Byte

External THERM Limit

0000 0000

11

0000 0000

12

0000 0000

13

0000 0000

14

0000 0000

19

0101 0101 (0x55) (85°C) (Note 2)

0101 0101 (0x55) (85°C)

0000 1010 (0x0A) (10°C)

0000 0001 (0x01)

0100 0001 (0x41)

20

Local THERM Limit

21

22

THERM Hysteresis

Consecutive ALERT

Not Applicable

Manufacturer ID

1. Writing to Address 0x0F causes the NVT210 to perform a single measurement. It is not a data register, and it does not matter what data is

written to it.

2. THERM limit for MSOP8 package = 85°C, THERM limit for WDFN8 package = 108°C.

Serial Bus Interface

indicates that an address/data stream follows. All

slave peripherals connected to the serial bus

respond to the start condition and shift in the next

eight bits, consisting of a 7-bit address (MSB first)

plus an R/W bit, which determines the direction of

the data transfer, that is, whether data is written to,

or read from, the slave device. The peripheral

whose address corresponds to the transmitted

address responds by pulling the data line low

during the low period before the ninth clock pulse,

known as the acknowledge bit. All other devices

on the bus remain idle while the selected device

waits for data to be read from or written to it. If the

R/W bit is a 0, the master writes to the slave

device. If the R/W bit is a 1, the master reads from

the slave device.

Control of the NVT210 is carried out via the serial bus.

The NVT210 is connected to this bus as a slave device, under

the control of a master device.

The NVT210 has an SMBus/I C timeout feature. When

this is enabled, the SMBus/I C times out after typically

25 ms of no activity. However, this feature is not enabled by

default. Bit 7 of the consecutive alert register

(Address = 0x22) should be set to enable it.

2

Addressing the Device

In general, every SMBus/I C device has a 7-bit device

2

address, except for some devices that have extended 10-bit

addresses. When the master device sends a device address

over the bus, the slave device with that address responds.

The NVT210 is available with one device address, 0x4C

(1001 100b). An NVT210D is also available.

The NVT210D has an SMBus/I C address of 0x4D

(1001 101b). This is to allow two NVT210 devices on the

same bus, or if the default address conflicts with an existing

2. Data is sent over the serial bus in a sequence of

nine clock pulses, eight bits of data followed by an

acknowledge bit from the slave device. Transitions

on the data line must occur during the low period

of the clock signal and remain stable during the

high period, since a low-to-high transition when

the clock is high can be interpreted as a stop

signal. The number of data bytes that can be

transmitted over the serial bus in a single read or

2

device on the SMBus/I C. The serial bus protocol operates

as follows:

1. The master initiates a data transfer by establishing

a start condition, defined as a high-to-low

transition on SDATA, the serial data line, while

SCLK, the serial clock line, remains high. This

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12

NVT210

write operation is limited only by what the master

and slave devices can handle.

without starting a new operation. For the NVT210,

write operations contain either one or two bytes,

while read operations contain one byte.

3. When all data bytes have been read or written,

stop conditions are established. In write mode, the

master pulls the data line high during the tenth

clock pulse to assert a stop condition. In read

mode, the master device overrides the

To write data to one of the device data registers, or to read

data from it, the address pointer register must be set so that

the correct data register is addressed. The first byte of a write

operation always contains a valid address that is stored in the

address pointer register. If data is to be written to the device,

the write operation contains a second data byte that is written

to the register selected by the address pointer register.

This procedure is illustrated in Figure 15. The device

address is sent over the bus followed by R/W set to 0. This

is followed by two data bytes. The first data byte is the

address of the internal data register to be written to, which

is stored in the address pointer register. The second data byte

is the data to be written to the internal data register.

acknowledge bit by pulling the data line high

during the low period before the ninth clock pulse.

This is known as no acknowledge. The master

takes the data line low during the low period

before the tenth clock pulse, then high during the

tenth clock pulse to assert a stop condition.

Any number of bytes of data are transferable over

the serial bus in one operation, but it is not

possible to mix read and write in one operation

because the type of operation is determined at the

beginning and cannot subsequently be changed

1

9

1

9

SCLK

R/W

A6 A5 A4

A3 A2 A1 A0

FRAME 1

SDATA

START BY

D7 D6 D5 D4 D3 D2 D1 D0

ACK. BY

NVT210

ACK. BY

NVT210

MASTER

FRAME 2

SERIAL BUS ADDRESS BYTE

ADDRESS POINTER REGISTER BYTE

1

9

SCLK (CONTINUED)

SDATA (CONTINUED)

D7 D6 D5 D4 D3 D2 D1 D0

ACK. BY

STOP BY

MASTER

NVT210

FRAME 3

DATA BYTE

Figure 15. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register

1

9

1

9

SCLK

R/W

D6

D2

FRAME 2

A6 A5 A4 A3 A2 A1 A0

D7

D5 D4 D3

D1

D0

SDATA

ACK. BY

NVT210

START BY

MASTER

ACK. BY STOP BY

MASTER

NVT210

FRAME 1

SERIAL BUS ADDRESS BYTE

ADDRESS POINTER REGISTER BYTE

Figure 16. Writing to the Address Pointer Register Only

9

1

9

SCLK

A6 A5 A4 A3 A2 A1 A0

R/W

SDATA

D6

D7

D5 D4 D3 D2 D1

FRAME 2

D0

ACK. BY

NVT210

START BY

ACK. BY STOP BY

MASTER

NVT210 MASTER

FRAME 1

SERIAL BUS ADDRESS BYTE

ADDRESS POINTER REGISTER BYTE

Figure 17. Reading Data from a Previously Selected Register

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13

NVT210

When reading data from a register there are two possibilities.

1. SMBALERT is pulled low.

2. Master initiates a read operation and sends the

alert response address (ARA = 0001 100). This is

a general call address that must not be used as a

specific device address.

3. The device whose ALERT output is low responds

to the alert response address and the master reads

its device address. As the device address is seven

bits, an LSB of 1 is added. The address of the

device is now known and it can be interrogated in

the usual way.

• If the address pointer register value of the NVT210 is

unknown or not the desired value, it is first necessary to

set it to the correct value before data can be read from

the desired data register. This is done by writing to the

NVT210 as before, but only the data byte containing

the register read address is sent, because data is not to

be written to the register see Figure 16.

A read operation is then performed consisting of the

serial bus address, R/W bit set to 1, followed by the

data byte read from the data register see Figure 17.

4. If more than one device’s ALERT output is low,

the one with the lowest device address takes

• If the address pointer register is known to be at the

desired address, data can be read from the

2

priority, in accordance with normal SMBus/I C

corresponding data register without first writing to the

address pointer register and the bus transaction shown

in Figure 16 can be omitted.

arbitration.

Once the NVT210 has responded to the alert response

address, it resets its ALERT output, provided that the error

condition that caused the ALERT no longer exists. If the

SMBALERT line remains low, the master sends the ARA

again, and so on until all devices whose ALERT outputs

were low have responded.

Notes:

• It is possible to read a data byte from a data register

without first writing to the address pointer register.

However, if the address pointer register is already at the

correct value, it is not possible to write data to a register

without writing to the address pointer register because

the first data byte of a write is always written to the

address pointer register.

• Some of the registers have different addresses for read

and write operations. The write address of a register

must be written to the address pointer if data is to be

written to that register, but it may not be possible to

read data from that address. The read address of a

register must be written to the address pointer before

data can be read from that register.

Low Power Standby Mode

The NVT210 can be put into low power standby mode by

setting Bit 6 of the configuration register. When Bit 6 is low,

the NVT210 operates normally. When Bit 6 is high, the ADC

is inhibited, and any conversion in progress is terminated

without writing the result to the corresponding value

2

register. However, the SMBus/I C is still enabled. Power

consumption in the standby mode is reduced to 5 mA if there

2

is no SMBus/I C activity, or 30 mA if there are clock and

data signals on the bus.

When the device is in standby mode, it is possible to

initiate a one-shot conversion of both channels by writing to

the one-shot register (Address 0x0F), after which the device

returns to standby. It does not matter what is written to the

one-shot register, all data written to it is ignored. It is also

possible to write new values to the limit register while in

standby mode. If the values stored in the temperature value

registers are outside the new limits, an ALERT is generated,

even though the NVT210 is still in standby.

ALERT Output

This is applicable when Pin 6 is configured as an ALERT

output. The ALERT output goes low whenever an

out-of-limit measurement is detected, or if the remote

temperature sensor is open circuit. It is an open-drain output

and requires a pullup resistor to V . Several ALERT outputs

can be wire-OR’ed together, so that the common line goes

low if one or more of the ALERT outputs goes low.

DD

The ALERT output can be used as an interrupt signal to a

processor, or as an SMBALERT. Slave devices on the

Sensor Fault Detection

2

SMBus/I C cannot normally signal to the bus master that

At its D+ input, the NVT210 contains internal sensor fault

detection circuitry. This circuit can detect situations where

an external remote diode is either not connected or

incorrectly connected to the NVT210. A simple voltage

they want to talk, but the SMBALERT function allows them

to do so.

One or more ALERT outputs can be connected to a

common SMBALERT line that is connected to the master.

When the SMBALERT line is pulled low by one of the

devices, the following procedure occurs (see Figure 18):

comparator trips if the voltage at D+ exceeds V − 1.0 V

DD

(typical), signifying an open circuit between D+ and D−.

The output of this comparator is checked when a conversion

is initiated. Bit 2 of the status register (open flag) is set if a

fault is detected. If the ALERT pin is enabled, setting this

flag causes ALERT to assert low.

If the user does not wish to use an external sensor with the

NVT210, tie the D+ and D− inputs together to prevent

continuous setting of the open flag.

MASTER RECEIVES SMBALERT

ALERT RESPONSE

ADDRESS

DEVICE

NO

ACK

START

RD ACK

STOP

ADDRESS

MASTER SENDS

ARA AND READ

COMMAND

DEVICE SENDS

ITS ADDRESS

Figure 18. Use of SMBALERT

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14

NVT210

TEMPERATURE

The NVT210 Interrupt System

1005C

905C

805C

705C

605C

505C

The NVT210 has two interrupt outputs, ALERT and

THERM. Both have different functions and behavior.

ALERT is maskable and responds to violations of software

programmed temperature limits or an open-circuit fault on

the external diode. THERM is intended as a fail-safe

interrupt output that cannot be masked.

If the external or local temperature exceeds the

programmed high temperature limits, or equals or exceeds

the low temperature limits, the ALERT output is asserted

low. An open-circuit fault on the external diode also causes

ALERT to assert. ALERT is reset when serviced by a master

reading its device address, provided the error condition has

gone away and the status register has been reset.

The THERM output asserts low if the external or local

temperature exceeds the programmed THERM limits.

THERM temperature limits should normally be equal to or

greater than the high temperature limits. THERM is reset

automatically when the temperature falls back within the

THERM limit. A hysteresis value can be programmed; in

which case, THERM resets when the temperature falls to the

limit value minus the hysteresis value. This applies to both

local and remote measurement channels. The power-on

hysteresis default value is 10°C, but this can be

reprogrammed to any value after powerup.

The hysteresis loop on the THERM outputs is useful when

THERM is used, for example, as an on/off controller for a

fan. The user’s system can be set up so that when THERM

asserts, a fan is switched on to cool the system. When

THERM goes high again, the fan can be switched off.

Programming a hysteresis value protects from fan jitter,

where the temperature hovers around the THERM limit, and

the fan is constantly switched.

THERM LIMIT

THERM LIMIT − HYSTERESIS

HIGH TEMP LIMIT

405C

RESET BY MASTER

4

ALERT

THERM

1

2

3

Figure 19. Operation of the ALERT and THERM

Interrupts

• If the measured temperature exceeds the high

temperature limit, the ALERT output asserts low.

• If the temperature continues to increase and exceeds the

THERM limit, the THERM output asserts low.

• The THERM output deasserts (goes high) when the

temperature falls to THERM limit minus hysteresis. In ,

the default hysteresis value of 10°C is shown.

• The ALERT output deasserts only when the

temperature has fallen below the high temperature

limit, and the master has read the device address and

cleared the status register.

• Pin 6 on the NVT210 can be configured as either an

ALERT output or as an additional THERM output.

• THERM2 asserts low when the temperature exceeds the

programmed local and/or remote high temperature

limits. It is reset in the same manner as THERM and is

not maskable.

Table 14. THERM HYSTERESIS

• The programmed hysteresis value also applies to

THERM2.

THERM Hysteresis

Binary Representation

0 000 0000

0°C

1°C

Figure 20 shows how THERM and THERM2 operate

together to implement two methods of cooling the system.

In this example, the THERM2 limits are set lower than the

THERM limits. The THERM2 output is used to turn on a

fan.

0 000 0001

10°C

0 000 1010

Figure 19 shows how the THERM and ALERT outputs

operate. The ALERT output can be used as a SMBALERT

to signal to the host via the SMBus/I C that the temperature

2

has risen. The user can use the THERM output to turn on a

fan to cool the system, if the temperature continues to

increase. This method ensures that there is a fail-safe

mechanism to cool the system, without the need for host

intervention.

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15

NVT210

100 W

TEMPERATURE

905C

D+

REMOTE

TEMPERATURE

SENSOR

THERM LIMIT

THERM2 LIMIT

805C

705C

605C

505C

1 nF

D−

Figure 21. Filter between Remote Sensor and

NVT210 Factors Affecting Diode Accuracy

405C

305C

Remote Sensing Diode

The NVT210 is designed to work with discrete transistors.

Substrate transistors are generally PNP types with the

collector connected to the substrate. Discrete types are either

PNP or NPN transistors connected as diodes (base-shorted

to collector). If an NPN transistor is used, the collector and

base are connected to D+ and the emitter to D−. If a PNP

transistor is used, the collector and base are connected to D−

and the emitter to D+.

1

4

THERM2

THERM

2

3

Figure 20. Operation of the THERM and THERM2

Interrupts

• When the THERM2 limit is exceeded, the THERM2

signal asserts low.

To reduce the error due to variations in discrete transistors,

consider several factors:

• If the temperature continues to increase and exceeds the

• The ideality factor, nF, of the transistor is a measure of

the deviation of the thermal diode from ideal behavior.

The NVT210 is trimmed for an nF value of 1.008. The

following equation may be used to calculate the error

introduced at a temperature, T (°C), when using a

transistor whose nF does not equal 1.008. Consult the

processor data sheet for the nF values.

THERM limit, the THERM output asserts low.

• The THERM output deasserts (goes high) when the

temperature falls to THERM limit minus hysteresis. In

Figure 20, there is no hysteresis value shown.

• As the system cools further, and the temperature falls

below the THERM2 limit, the THERM2 signal resets.

Again, no hysteresis value is shown for THERM2.

DT = (nF − 1.008)/1.008 × (273.15 Kelvin + T)

Both the external and internal temperature measurements

cause THERM and THERM2 to operate as described.

To factor this in, the user writes the DT value to the offset

register. It is then automatically added to, or subtracted

from, the temperature measurement.

Application Information

Noise Filtering

If a discrete transistor is used with the NVT210, the best

accuracy is obtained by choosing devices according to the

following criteria:

• Base-emitter voltage greater than 0.25 V at 6 mA, at the

highest operating temperature

For temperature sensors operating in noisy environments,

the industry standard practice was to place a capacitor across

the D+ and D− pins to help combat the effects of noise.

However, large capacitances affect the accuracy of the

temperature measurement, leading to a recommended

maximum capacitor value of 1,000 pF. Although this

capacitor reduces the noise, it does not eliminate it, making

it difficult to use the sensor in a very noisy environment.

The NVT210 has a major advantage over other devices

when it comes to eliminating the effects of noise on the

external sensor. The series resistance cancellation feature

allows a filter to be constructed between the external

temperature sensor and the part. The effect of any filter

resistance seen in series with the remote sensor is

automatically cancelled from the temperature result.

The construction of a filter allows the NVT210 and the

remote temperature sensor to operate in noisy environments.

Figure 21 shows a low-pass R-C-R filter, where R = 100 W

and C = 1 nF. This filtering reduces both common-mode and

differential noise.

• Base-emitter voltage less than 0.95 V at 100 mA, at the

lowest operating temperature

• Base resistance less than 100 W

• Small variation in h (50 to 150) that indicates tight

FE

control of V characteristics

BE

Transistors, such as the 2N3904, 2N3906, or equivalents

in SOT−23 packages are suitable devices to use.

Thermal Inertia and Self-heating

Accuracy depends on the temperature of the remote

sensing diode and/or the internal temperature sensor being

at the same temperature as that being measured. Many

factors can affect this. Ideally, place the sensor in good

thermal contact with the part of the system being measured.

If it is not, the thermal inertia caused by the sensor’s mass

www.onsemi.com

16

NVT210

causes a lag in the response of the sensor to a temperature

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

can cause thermocouple effects. Where copper/solder

joints are used, make sure that they are in both the D+

and D− path and at the same temperature.

• Thermocouple effects should not be a major problem as

1°C corresponds to about 200 mV, and thermocouple

voltages are about 3 mV/°C of temperature difference.

Unless there are two thermocouples with a big

change. In the case of the remote sensor, this should not be

a problem since it is either a substrate transistor in the

processor or a small package device, such as the SOT−23,

placed in close proximity to it.

The on-chip sensor, however, is often remote from the

processor and only monitors the general ambient

temperature around the package. How accurately the

temperature of the board and/or the forced airflow reflects

the temperature to be measured dictates the accuracy of the

measurement. Self-heating due to the power dissipated in

the NVT210 or the remote sensor causes the chip

temperature of the device or remote sensor to rise above

ambient. However, the current forced through the remote

sensor is so small that self-heating is negligible. In the case

of the NVT210, the worst-case condition occurs when the

device is converting at 64 conversions per second while

sinking the maximum current of 1 mA at the ALERT and

THERM output. In this case, the total power dissipation in

temperature differential between them, thermocouple

voltages should be much less than 200 mV.

• Place a 0.1 mF bypass capacitor close to the V pin. In

DD

extremely noisy environments, place an input filter

capacitor across D+ and D− close to the NVT210. This

capacitance can effect the temperature measurement, so

ensure that any capacitance seen at D+ and D− is, at

maximum, 1,000 pF. This maximum value includes the

filter capacitance, plus any cable or stray capacitance

between the pins and the sensor diode.

• If the distance to the remote sensor is more than

8 inches, the use of twisted pair cable is recommended.

A total of 6 feet to 12 feet is needed.

the device is about 4.5 mW. The thermal resistance, q , of

the 8-lead DFN is approximately 142°C/W.

JA

Layout Considerations

For really long distances (up to 100 feet), use a shielded

twisted pair, such as the Belden No. 8451 microphone

cable. Connect the twisted pair to D+ and D− and the

shield to GND close to the NVT210. Leave the remote

end of the shield unconnected to avoid ground loops.

Digital boards can be electrically noisy environments, and

the NVT210 is measuring very small voltages from the

remote sensor, so care must be taken to minimize noise

induced at the sensor inputs. Take the following precautions:

• Place the NVT210 as close as possible to the remote

sensing diode. Provided that the worst noise sources,

that is, clock generators and data/address buses are

avoided, this distance can be 4 inches to 8 inches.

• Route the D+ and D– tracks close together, in parallel,

with grounded guard tracks on each side. To minimize

inductance and reduce noise pickup, a 5 mil track width

and spacing is recommended. Provide a ground plane

under the tracks, if possible.

Because the measurement technique uses switched

current sources, excessive cable or filter capacitance can

affect the measurement. When using long cables, the filter

capacitance can be reduced or removed.

Application Circuit

Figure 23 shows a typical application circuit for the

NVT210, using a discrete sensor transistor connected via a

shielded, twisted pair cable. The pullups on SCLK, SDATA,

and ALERT are required only if they are not provided

elsewhere in the system.

GND

D+

5 MIL

D−

GND

Figure 22. Typical Arrangement of Signal Tracks

www.onsemi.com

17

NVT210

V

DD

V

DD

V

DD

0.1 mF

TYP 10 kW

NVT210

SCLK

D+

2

SDATA

SMBus/I C

CONTROLLER

ALERT/

THERM2

D−

SHIELD

2N3906

V

DD

THERM

TYP 10 kW

GND

OVERTEMPERATURE

SHUTDOWN

Figure 23. Typical Application Circuit

Table 15. ORDERING INFORMATION

Package

Option

SMBus

Address

THERM

Limit

†

Description

8-lead MSOP

8-lead WDFN

Device Order Number*

NVT210CDM3R2G

NVT210DDM3R2G

NVT210CMTR2G

Marking

210C

210D

VC

Shipping

DM

MT

0x4C

85°C

3,000 Tape & Reel

0x4D

85°C

0x4C

108°C

NVT210DMTR2G

VD

0x4D

†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.

*The “G’’ suffix indicates Pb-Free package available.

www.onsemi.com

18

NVT210

PACKAGE DIMENSIONS

MSOP8

CASE 846AB

ISSUE O

D

NOTES:

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

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.

H

E

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.

PIN 1 ID

MILLIMETERS

INCHES

NOM

−−

0.003

0.013

0.007

0.118

e

DIM

A

A1

b

c

D

E

e

L

MIN

−−

0.05

0.25

0.13

2.90

NOM

−−

0.08

0.33

0.18

3.00

MAX

MIN

−−

0.002

0.010

0.005

0.114

MAX

0.043

0.006

0.016

0.009

0.122

b 8 PL

1.10

0.15

0.40

0.23

3.10

M

S

0.08 (0.003)

T B

A

0.118

SEATING

PLANE

0.65 BSC

0.55

4.90

0.026 BSC

0.021

0.193

−T−

0.40

4.75

0.70

5.05

0.016

0.187

0.028

0.199

A

0.038 (0.0015)

H

E

L

A1

c

SOLDERING FOOTPRINT*

1.04

0.38

8X

^8X0.041

0.015

3.20

0.126

4.24

0.167 0.208

5.28

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.

www.onsemi.com

19

NVT210

PACKAGE DIMENSIONS

WDFN8 2x2, 0.5P

CASE 511AT

ISSUE O

L

D

A

B

NOTES:

1. DIMENSIONING AND TOLERANCING PER

ASME Y14.5M, 1994.

2. CONTROLLING DIMENSION: MILLIMETERS.

3. DIMENSION b APPLIES TO PLATED

TERMINAL AND IS MEASURED BETWEEN

0.15 AND 0.30 MM FROM TERMINAL TIP.

L1

PIN ONE

REFERENCE

DETAIL A

E

ALTERNATE TERMINAL

CONSTRUCTIONS

MILLIMETERS

DIM

A

MIN

0.70

0.00

MAX

0.80

0.05

2X

0.10

C

A1

A3

b

0.20 REF

2X

0.10

C

0.20

0.30

EXPOSED Cu

MOLD CMPD

TOP VIEW

2.00 BSC

D

E

2.00 BSC

0.50 BSC

e

DETAIL B

L

0.40

---

0.60

0.15

0.70

0.05

C

L1

L2

DETAIL B

0.50

A

ALTERNATE

CONSTRUCTIONS

8X

0.05

C

A1

A3

SIDE VIEW

SEATING

PLANE

C

RECOMMENDED

SOLDERING FOOTPRINT*

7X

0.78

PACKAGE

OUTLINE

e/2

e

DETAIL A

7X

L

4

1

L2

2.30

0.88

8

5

1

8X

b

0.50

8X

0.30

0.10

C

A

B

PITCH

NOTE 3

0.05

C

DIMENSIONS: MILLIMETERS

BOTTOM VIEW

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

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

2

ON Semiconductor is licensed by Philips Corporation to carry the I C Bus Protocol.

ON Semiconductor and the

are registered trademarks of Semiconductor Components Industries, LLC (SCILLC) or its subsidiaries in the United States and/or other countries.

SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed

at www.onsemi.com/site/pdf/Patent−Marking.pdf. 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: 81−3−5817−1050

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

NVT210/D

www.onsemi.com

20


型号：	NVT210DMTR2G
厂家：	ONSEMI
描述：	Temperature Monitor 光电二极管
文件：	总20页 (文件大小：303K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

NVT210DMTR2G [ONSEMI]

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