Measuring Temperature with the

文章摘要：TACTUAL = g(TMEAS) + TOFFSETEquation 3. Gain and offset correction equation.Procedure for Gain and Offset CorrectionThe procedure for adding the gain and offset correction is detailed below. The procedure reads the values from the gain and offset correction registers. The gain and offset amounts are

Measuring Temperature with the,标签：模拟电子技术基础,模拟电子电路,http://www.88dzw.com

T_ACTUAL = g(T_MEAS) + T_OFFSET
Equation 3. Gain and offset correction equation.

Procedure for Gain and Offset Correction

The procedure for adding the gain and offset correction is detailed below. The procedure reads the values from the gain and offset correction registers. The gain and offset amounts are then computed using two formulas. The resulting correction values are applied to Equation 3 above.

Step 1. Measure and Calculate the Temperature

Use the procedure for the internal or the external transistor and save the result as T_MEAS for use in the correction formula above.

Step 2. Read the TGAIN Register

Read the TEMP_CAL register and save the upper byte TGAIN[7:0] for use in the formula below. It should be saved as a type-signed integer.

Step 3. Calculate the Gain Correction Factor

Using the value saved above, apply this value to the gain formula below.

Gain = 0.9025 + TGAIN × 0.000576
Equation 4. Gain formula equation.

Step 4. Read the TOFFS Register

Read the TEMP_CAL register and save the lower byte TOFFS[5:0] for use in the formula below. The data should be saved as a type-signed integer. Do not right-shift the data.

Step 5. Calculate the Offset Correction Factor

Using the offset value saved above, apply this value to the gain formula below.

Offset = -14.0 + TOFFS × 0.3125
Equation 5. Offset correction equation.

Step 6. Calculate the corrected Temperature

Use the gain and offset values calculated above in the temperature equation below.

T_ACTUAL = GAIN × T_MEAS + OFFSET

Conclusion

The MAX1358 features internal circuitry to measure the internal die temperature. The internal circuitry can also be used with an external transistor for a low-cost remote temperature sensor. The four-current temperature measurement method described in this application note can be used to achieve the ±0.5 and ±1.0 typical accuracy specified in the MAX1358 data sheet.

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