Once the top and bottom resistors are
known, calculate the expected nominal output voltage using Equation 3. As the reference and the resistor values have deviations from the nominal values
(or uncertainties), the designer can calculate the expected output voltage error
using Equation 4. Equation 4 is calculated using the derivative method, and assumes the error variables are
uncorrelated, and both resistors (RF_TOPx and RF_BOTx) have
the same tolerance. The real output voltage range can be calculated using Equation 5.
Equation 3.
Equation 4.
Equation 5.
where:
- RF_TOPx is the
selected top resistor for the resistive voltage divider in Ohms (Ω).
- RF_BOTx is the
selected bottom resistor for the resistive voltage divider in Ohms (Ω).
- VREFx = 599.48mV (typ. at 25°C) or 598.39mV (center
across temperature).
- VREFx_ACC is the
reference accuracy as a numeric value (0.01). The accuracy across voltage
and temperature is ± 1%, for more details refer
to VOLTAGE REFERENCE in Section 6.5.
- RTOL is the
resistor tolerance (same for the top and bottom resistors) as a numeric
value. For example, for a 0.1% tolerance resistors, 0.001 is used.