The resistors of the RES60A-Q1 are described by the following two equations:
Equation 1.
Equation 2.
where
- RHVnom and RLVnom are the nominal values of each resistor.
- tabs is an error term that
describes the absolute tolerance of the resistors of the RES60A-Q1, such that |tabs| ≤ 15%.
- tSiCr is the variation in the SiCr resistivity for a
wafer, and dominates the absolute tolerance for a given resistor. The two resistors of a
given RES60A-Q1 are interdigitated and come from the same
area of the wafer; therefore, tSiCr is effectively the same for both of the two
resistors, although tSiCr varies on a part-to-part basis. When the divider is
considered in ratiometric terms, these error terms drop out; see the following equations.
- tRHV and tRLV are
localized per-resistor variation or offset error terms. These terms describe the remaining
effective tolerances of the respective resistors for a given RES60A-Q1 device, after accounting for the universal tSiCr.
Equation 3.
Equation 4.
The RES60A-Q1
is specified with a maximum initial divider ratio tolerance of 0.1%, meaning that the relationship between the actual divider ratio, G, and the
nominal ratio, Gnom, of a given divider is described by the following:
Equation 5.
such that tD ≤ 0.1%. Because any devices that do not meet these criteria
are screened out at final test, these equations can be used with the previous equations to
prove the effective bounds of tRHV and tRLV. Therefore, despite the
device absolute end-to-end tolerance bounds of ±15%, the
effective error tolerances of each resistor (for ratiometric applications) are within
approximately ±0.05%, for the worst-case
tRHV and tRlV.