TMP411CD datasheet(32/48 Pages) TI2

32 / 48 page

ERR

1.004 1.008

273.15 100 C

1.008

1.48 C

· u

ERR

n 1.008

273.15

T( C)

1.008

· u

TMP411

SBOS383D – DECEMBER 2006 – REVISED DECEMBER 2016

www.ti.com

Product Folder Links: TMP411

Submit Documentation Feedback

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

The TMP411 only requires a transistor connected between the D+ and D– pins for remote temperature

measurement. Tie the D+ pin to D– if the remote channel is not used and only the local temperature is

measured. The SDA, ALERT and THERM pins (and SCL, if driven by an open-drain output) require pullup

resistors as part of the communication bus. TI recommends using a 0.1-µF power-supply decoupling capacitor

for local bypassing. Figure 11 illustrates the typical configurations for the TMP411.

10.2 Typical Application

10.2.1 Design Requirements

The TMP411 is designed to be used with discrete transistors or substrate transistors built into processor chips

and ASICs. NPN or PNP transistors can be used, as long as the base-emitter junction is the remote temperature

sensor. A transistor or diode connection can be used, as shown in Figure 11.

Errors in remote temperature sensor readings are the result of the ideality factor and current excitation from the

TMP411 versus the manufacturer-specified operating current for a given transistor. Some manufacturers specify

a high-level and low-level current for the temperature-sensing substrate transistors. The TMP411 has an ILOW

value of 6 μA, and an IHIGH value of 120 μA. The TMP411 allows for different n-factor values, as shown in

Table 8.

The ideality factor (n) is a measured characteristic of a remote temperature sensor diode compared to an ideal

diode. The ideality factor reduces to a value of 1.008. For transistors with an ideality factor that does not match

the TMP411, Equation 4 calculates the temperature error. Note that the actual temperature (°C) must be

converted to Kelvin (°K) for the equation to yield the correct results.

where:

•

n = the ideality factor of the remote temperature sensor

•

T(°C) = actual temperature

•

TERR = device reading error due to n ≠ 1.008

•

Degree delta is the same for °C and °K

(4)

For n = 1.004 and T(°C) = 100°C, use Equation 5:

(5)

If a discrete transistor is used as the remote temperature sensor, selecting the transistor according to the

following criteria results in the best accuracy.

1. Base-emitter voltage > 0.25 V at 6 µA, at the highest sensed temperature.

2. Base-emitter voltage < 0.95 V at 120 µA, at the lowest sensed temperature.

3. Base resistance < 100 Ω

4. Tight control of VBE characteristics indicated by small variations in hFE (that is, 50 to 150).

TMP411CD Datasheet(PDF) 32 Page - Texas Instruments

TMP411CD Datasheet(HTML) 32 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Datasheet Download

Link URL