Help with resistor divider for undervoltage overvotage and bidirectional circuit breaker application

Thread Starter

mike__MecE

Joined Feb 20, 2022
92
I am attempting to implment the LTC4368 (datasheet attached).
1738985454491.png
(Edit 2025-02-07 - replaced image of LTC4369 and example circuit above with one from the datasheet including labels R1-R4, I would also like to clarify that the above example is only to illustrate the circuit design and layout and does not represent my required OV and UV, nor Vin, nor current limit.)
I have determined the values of R1, R2, R3 based on the guidance of "Procedure for Selecting UV/OV External Resistor Values" on pg. 12 of 22. See table below.

However, I cannot determine how R4 is selected. R4 occurs between Vin and SHDN. I am seeking assistance determining how to select R4. I have done some research regarding voltage dividers, but I am not sure what the target voltage at SHDN would be.

ParameterValueUnits
V_OSUV_Target0.003000000V
I_UV_Target0.000000010A
UV_TH_Target42.000000000V
OV_TH_Target58.000000000V
R1+R2_Target300,000.000000000Ohms
R3_Target24,900,000.000000000Ohms
R3_Selected25,000,000.000000000Ohms
R1_Target218,103.448275862Ohms
R1_Selected218,000.000000000Ohms
R2_Target82,000.000000000Ohms
R2_Selected82,000.000000000Ohms
UV_TH_Actual42.166666667V
OV_TH_Actual58.027522936V
 

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Thread Starter

mike__MecE

Joined Feb 20, 2022
92
So which resistor is which? On the schematic you have not labeled anything.
Hi, R1-R4 are identified on pg. 9/22 among other places in the datasheet. For convenience, I replaced the image in my post with one showing R1-R4 on the schematic.
@Lightium
 
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