SLVSFQ6A November 2020 – June 2021 TPS2640
PRODUCTION DATA
The undervoltage lockout (UVLO) and overvoltage trip point are adjusted using an external voltage divider network of R1, R2 and R3 connected between IN, UVLO, OVP and RTN pins of the device. The values required for setting the undervoltage and overvoltage are calculated by solving Equation 9 and Equation 10.
For minimizing the input current drawn from the power supply {I(R123) = V(IN)/(R1+R2+R3)}, it is recommended to use higher value resistance for R1, R2 and R3.
However, the leakage current due to external active components connected at resistor string can add error to these calculations. So, the resistor string current, I(R123) must be chosen to be 20x greater than the leakage current of UVLO and OVP pins.
The UVLO and the OVP pins can also be connected to the RTN pin to enable the internal default V(OV) = 33 V and V(UV) = 15 V.
The power failure is detected on falling edge of the supply. This threshold voltage is 7.5% lower than the rising threshold, V(UV). The voltage at which the device detects power fail can be calculated using Equation 12.