RES11A10DDFR datasheet(21/56 Pages) TI2

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7.3.3 Predictable Voltage Coefficient

The voltage coefficients of the RES11A are largely related to self-heating, where the power dissipated in the

device raises the die temperature. As previously mentioned, the commonality of this temperature rise leads to a

comparable shift in each resistor, such that the divider ratio is well preserved.

Applying voltage V across resistor R results in the loss of a corresponding power dissipation of P = V2 / R,

in the form of heat in the device die. This heat leads to a localized increase in the junction temperature,

which in turn causes the same parametric shifts previously discussed in the context of temperature coefficients.

TCR is specified as a function of ambient temperature; therefore, use the effective junction-to-ambient thermal

resistance to determine the effective temperature rise and calculate the nominal or expected shift.

Rexpected=Rinitial+VR2R×RθJAeffective×TCRabs×Rinitial

(16)

If two dividers are biased simultaneously, the power dissipation of both dividers must be summed before

calculating the associated junction temperature rise using the junction-to-ambient thermal resistance.

The following figures show a data set from one RES11A40 unit tested at various voltages.

Voltage (V)

969.75

970

970.25

970.5

970.75

971

RIN1 Calculated

RIN2 Calculated

RIN1 Measured

RIN2 Measured

Figure 7-7. RIN Resistance vs Divider Voltage

Voltage (V)

3878.5

3879

3879.5

3880

3880.5

3881

3881.5

3882

3882.5

3883

3883.5

RG1 Calculated

RG2 Calculated

RG1 Measured

RG2 Measured

Figure 7-8. RG Resistance vs Divider Voltage

The difference of the expected value of R from the actual value of R describes the actual-to-expected mismatch

error of R, due to non-temperature-related effects on the voltage coefficient. Similar to the logarithmic conformity

error of a logarithmic amplifier or the integrated nonlinearity error of an ADC, this error describes the deviations

of the actual device behavior from the predictable behavior. While the absolute magnitude of the shift varies,

the slope or trend is predictable. Note that measurement noise and leakages can easily increase the measured

error; follow best practices such as cleaning and baking circuit boards after assembly to minimize external errors

and improve repeatability.

The change in the measured value of R is divided by the change in bias voltage VR to calculate the effective

voltage coefficient of resistance. For example, the voltage coefficient of RIN1 is ΔRIN1 divided by ΔVRIN1.

Voltagecoefficient(Ω/V)= Rfinal–Rinitial

VR(final)–VR(initial)

(17)

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RES11A

SLPS785A – DECEMBER 2023 – REVISED OCTOBER 2025

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