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UCC25800-Q1: UCC25800-Q1

Raphael Fuchs-Robetin
Prodigy 10 points
Part Number: UCC25800-Q1

Hello 

We are currently designing a dual voltage supply, and we have the problem that our IC goes into error mode if more than 220mA are drawn or after 20 min goes also into error with 190mA. We measured our deltaU which is stated on page 20 of the datasheet with 400mV (which implies a R_th value of 8kOhm, we used R_a = 24.9kOhm and R_b = 12kOhm, and a 1uF cap from V_reg to GND) which should set our current to OCP1_4 660mA (assuming I_OCP1max = 1A). What could be the problem? Furthermore, we would like to ask if the values for R_th in Table 8-1 OCP Settings for are really so strict? What happens if the value of R_th is outside of the allowed intervalls because of tolerances?

  • 0
    TI__Guru 54055 points

    Hi,

    You need to make the resistor value of R_th in a range of the table 8-1 as the IC internal circuit can only tell what to do in one of these ranges. Outside of any ranges the IC internal circuit cannot make correct decision so the IC can make strange behavior, i.e., mal function.

    If you see a fault, please capture FLT waveform to decide which fault then making fix accordingly. 

    The current IC draw should related to your load or load resistance when load resistance increase then less current. So you need monitor the load current to see if you load current gets lower when you see IC current gets smaller.