SLVS493E March 2004 – April 2022 TPS65130 , TPS65131
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The output voltage of the inverting converter stage can also be adjusted with an external resistor divider. It must be connected to the FBN pin. Unlike the feedback divider at the boost converter, the reference point of the feedback divider is not GND but VREF. So the typical value of the voltage at the FBN pin is 0 V. The minimum recommended output voltage at the inverting converter is –15 V. Feedback divider current considerations are similar to the considerations at the boost converter. For the same reasons, the feedback divider current should be in the range of 5 µA or greater. The voltage across R4 is 1.213 V. Based on those values, the recommended value for R4 should be lower than 200 kΩ to set the divider current at the required value.
Calculate the value of resistor R3, as a function of the needed output voltage (VNEG), with Equation 2:
In this example, with R4 = 121.2 kΩ, choose R3 = 1 MΩ to set VNEG = –10 V.