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LM2941: LM2941 maximum output voltage limit 20V

user1255570
Prodigy 10 points
Part Number: LM2941
Other Parts Discussed in Thread: LP2954, , TPS7A47

Hello

I need to drop my 24V input voltage to 24V - 0V5 - Vdo, i.e. ideally around 23V, to mitigate line voltage droops due to varying loads, and provide a necessarily stable output voltage. The load current is a constant 250mA. I want to minimize the voltage drop for both thermal and operational reasons, and this led me to search for an LDO regulator which meets these requirements. I was immediately surprised at how few suitable regs there are which meet the spec (although realizing that most LDO applications are low voltage): in the TI roster I could find only the LP2954, which I knew would be running right on the beam ends. On testing one on a representative area of bare 1oz PCB material, with only the GND pin connected to the copper area, at > 230mA current it rapidly went into thermal limiting. The LM2941 in TO263 looked more appealing, but the stated maximum output voltage is 20V, so no go. Micrel/Microchip offer the MIC2941A which does support >20V Vo. I have tested this and it appears to work very well. Now I know that TI does not publish absolute maximum ratings just for kicks and giggles!, but what is the exact reason for the the 20V limit and what would be the likely consequences of exceeding it by 3V?

  • 0
    TI__Intellectual 1146 points

    Hello,

    The 20V limit on the LM2941 pertains to the existing test data in the Electrical Characteristics section of the datasheet.In this case we can only guarantee performance to the tested limits of the LDO.

    With newer LDOs you will typically see a recommended operating condition as well as a maximum operating condition that specifies the full range of operation. Unfortunately this data is missing today on the LM2941.

    For some of the older regulators like this we have data missing in operating conditions, so it is difficult to specify what will happen with this device. Although we do not have a specified maximum voltage I would strongly recommend you to verify in this in your design and conduct the appropriate application-specific tests.

    On the other hand our TPS7A47 can help address your regulation needs and has a better thermal relieve due to it's thermal pad.