SLVSET9G September 2018 – April 2026 TPS1663
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 GND pins of the device. The values required for setting the undervoltage and overvoltage are calculated by solving Equation 11 and Equation 12.
For minimizing the input current drawn from the power supply:
TI recommends 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 20 times greater than the leakage current of UVLO and OVP pins.
From the device electrical specifications, V(OVPR) = 1.2V and V(UVLOR) = 1.2V. From the design requirements, V(OV) is 55V and V(UV) is 18V. To solve the equation, first select the value of R3 = 20.5kΩ and use Equation 11 to solve for (R1 + R2) = 930kΩ. Use Equation 12 and value of (R1 + R2) to solve for R2 = 43kΩ and finally R1 = 887kΩ.
select the closest standard 1% resistor values: R1 = 887kΩ, R2 = 43kΩ, and R3 = 20.5kΩ.