ZHCSIQ0F August 2018 – August 2020 TPS2120 , TPS2121
PRODUCTION DATA
In this example, the device will switch from IN1 to IN2 when the voltage on IN1 drops below 7.6 V. Therefore, the voltage on PR1 needs to remain higher than the voltage on CP2 until this condition exists.
Since this example was tested on the TPS2121EVM, the resistor divider configured the voltage on CP2 to be 1.644 V.
See Equation 12 for the VCP2 Calculation
Since the voltage on CP2 is higher than VREF, fast switchover mode is enabled.
Next, to calculate the necessary resistor divider on PR1, the voltage on PR1 needs to drop below 1.64 V when IN1 reaches 7.6 V. On the EVM, the PR1 resistors were configured as followed:
See Equation 13 for the VPR1 Caculation