JAJSET0B December 2018 – October 2019 TPS7A26
PRODUCTION DATA.
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For this design example, VOUT is set to 5 V. The following equations set the output voltage:
For improved output accuracy, use Equation 11 and IFB(TYP) = 10 nA as listed in the Electrical Characteristics table to calculate the upper limit for series feedback resistance, R1 + R2 ≤ 5 MΩ.
The control-loop error amplifier drives the FB pin to the same voltage as the internal reference (VFB = 1.24 V as listed in the Electrical Characteristics table). Use Equation 10 to determine the ratio of R1 / R2 = 3.03. Use this ratio and solve Equation 11 for R2. Now calculate the upper limit for R2 ≤ 1.24 MΩ. Select a standard value resistor of R2 = 1.18 MΩ.
Reference Equation 10 and solve for R1:
From Equation 12, R1 = 3.64 MΩ can be determined. Select a standard resistor value for R1 = 3.6 MΩ. From Equation 10, select VOUT = 5.023 V.