TMP007 datasheet(23/55 Pages) TI

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OBJ _ FINAL[n]

OBJ[n]

OBJ _ FINAL[n 1]

0.2

0.8

OBJ

OBJ _ Measured

DIE _ SLOPE

OBJ _ SLOPE

TC0 T

TC1 V

TMP007

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SBOS685C – APRIL 2014 – REVISED JULY 2015

7.4 Device Functional Modes

7.4.1 Temperature Transient Correction

Because the measured object temperature depends on TDIE, transient thermal events that change the die

temperature affect the measurement. To compensate for this effect, the TMP007 math engine incorporates a

transient correction option for use in applications where a thermal transient is anticipated. When transient

correction is turned on, a filter with programmable coefficients is used to modify the sensor voltage result before

the object temperature is calculated. This function helps reduce the jump in the object temperature result when

there are large transients of the local die temperature, TDIE. The compensation incorporates the rate of change of

TDIE and of VOBJ. The modified value for the sensor voltage used in VSENSOR to calculate the object temperature

is shown in Equation 9:

where

•

TC0 and TC1 are weighting coefficients programmable using the registers.

•

TDIE_SLOPE is the change in die temperature with time.

•

VOBJ_SLOPE is the change in sensor voltage with time.

(9)

As a general guideline, turn on transient correction when the local temperature is changing at a rate greater than

1.5°C/min. When transient correction is on, the function corrects transients up to approximately 20°C/min.

Turning on the transient correction also turns on the output filter shown in Equation 10:

(10)

If only the use of the output filter is desired without the input transient correction arithmetic, set the TC0 and TC1

coefficient values to 0 with TC bit in configuration register set to 1. When transition correction is on, the response

to a step change has a time constant of approximately five times the sampling time.

When transient correction is on, the math engine modifies the sensor voltage result based on the transient

correction equations. The nonmodified sensor voltage can be recovered with TC on by setting the TC1 and TC0

coefficients to 0. The output filtering cannot be turned off with TC bit set to 1.

7.4.2 Alert Modes: Interupt (INT) and Comparator (COMP)

The INT mode maintains the alert condition until a host controller clears the alert condition by reading the status

management system. The COMP mode asserts the ALERT pin and flags whenever the alert condition occurs,

and deasserts the ALERT pin and flags without external intervention when the alert condition is no longer present

This mode is often used to notify an external agent of an alert condition.

When servicing an alert from the TMP007, in some cases it may be useful to validate the alert condition by

checking the status of the nDV, MEM_CRPT, and DATA_OVF flags.

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