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LP3878-ADJ: LP3878 operating range

Jayanth Kruttiventi
Intellectual 1360 points
Part Number: LP3878-ADJ
Other Parts Discussed in Thread: TPS746, TLV759P, TLV767, TLV758P, TPS745

Hi,

 

My cusotmer is using LP3878ADJ for their 3.3V input and 2.5V output rail and 500mA out max load current. The dropout voltage is 800mV max but there is operating range requirement in section 7.4.1 which say Vin should be Vout+2V. let me know if this is required? 

 

Jay

  • 0
    TI__Genius 10200 points

    Hi Jay,

    Yes, this is required to ensure proper operation and output regulation. Figures 5, 6, and 7 of the datasheet show the typical minimum operating input voltage for different output voltages, load currents, and operating temperatures. 

    For the given operating conditions, the TLV767, TPS745, TPS746, TLV758P, and TLV759P may be some suitable alternatives. 

    Thanks,

    Gerard

  • 0 in reply to Gerard Copeland
    TI__Intellectual 1360 points

    Gerard,

    If the max load is 200mA, do we still have any issue in my condition. From the figures, I see that when the output voltage is 1V, you need more margin on the input voltage. But if the output votlage is 2.5V, I dont see why you need input voltage which should be Vout+2V. I think 3.3V input should be good enough. Do you agree?

    From the figure5,6  and 7 I dont see any issues with 3.3V input and 2.5V output and 200mA of load current and we are with in the spec limits.

    Thanks,

    Jay

  • 0 in reply to Jayanth Kruttiventi
    TI__Genius 10200 points
    Hi Jay,

    The figures show that a typical device may be able to regulate at your conditions. However, a minimum headroom (Vin - Vout) of 2 V is required to ensure that all devices properly regulate the desired output voltage across the full load and operating temperature range.

    Thanks,
    Gerard