JAJSLG4 december 2022 LM7480
PRODUCTION DATA
Resistors R2 and R3 connected in series is used to program the overvoltage threshold. Connecting R2 to VBATT provides overvoltage cut-off and switching the connection to VOUT provides overvoltage clamp. The resistor values required for setting the overvoltage threshold VOV to 37.0 V is calculated by solving Equation 7.
For minimizing the input current drawn from the battery through resistors R2 and R3, it recommended to use higher value of resistance. Using high value resistors will add error in the calculations because the current through the resistors at higher value will become comparable to the leakage current into the OV pin. Maximum leakage current into the OV pin is 1 µA and choosing (R2 + R3) < 120 kΩ ensures current through resistors is 100 times greater than leakage through OV pin.
Based on the device electrical characteristics, VOVR is 1.233V V. To limit (R2 + R3) < 120 kΩ, select (R2) = 100 kΩ. Solving Equation 7 gives R3 = 3.45 kΩ.
Closest standard 1% resistor values are R2 = 100 kΩ and R3 = 3.48 kΩ.