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LM2623EV: LM2623EV Min. Input Voltage

Eralp Gogen
Prodigy 55 points
Part Number: LM2623EV
Other Parts Discussed in Thread: LM2623,

Hi,

I am designing a battery powered board. My battery voltage drops to 1.6 V. So I wanted to use LM2623 Step-Up Converter (PCB draws 200mA@1.6V). I read LM2623' datasheet and LM2623EV's datasheet. On the LM2623EV's datasheet it is written that min input voltage is 2.3V but LM2623's datasheet says min input voltage is 0.8 V.

Which one shoul I consider ?

Best Regards

  • 0
    TI__Mastermind 34201 points

    Hi Eralp,

    LM2623 needs a 1.1V input startup voltage, after that the device could work down to 0.8V min input voltage.

    The LM2623 EVM circuit is designed for a specific application, which input voltage range is 2.3V to 5.5V. 

    May I know the working conditions of your application, Vin range, Vout, Ioutmax? So that I can recommend you a most suitable boost converter device. 

  • 0 in reply to Zack Liu
    Prodigy 55 points

    Hello Zack,

    Thank you for fast responsing. Could you please suggest us a boost converter in SOT package (for easy soldering process).

    Vin: min: 1.5 V

    max: 6 V

    Vout : min: 5 V

     max: 7-8 V

    Iout : max 1A

    Operating Temp: -40° C to +50° C

    Thank you

    Best Regards

  • 0 in reply to Eralp Gogen
    TI__Mastermind 34201 points

    Hi Eralp,

    May I know why the minimum input voltage is so low, only 1.5V?

    The maximum output power is 8V*1A=8W. If it is a constant output power, it means the average input current is 8W/1.5/0.85=6.27A. It's a quite big input current. Or is it a pulse 1A load current?

  • 0 in reply to Zack Liu
    Prodigy 55 points

    Hi,

    Our peak current is 1 A but awerage current is around 200mA. Our battery voltage drops because of the operating temperature.

    Best Regards

  • 0 in reply to Eralp Gogen
    TI__Mastermind 34201 points

    Hi Eralp,

    It depends on how long time the 1A peak current is. If the 1A peak current time is more than 10ms, it means a constant 1A load current to high switching frequency DCDC converter because normally the Fsw is over 500kHz and the load transient respond time is less than 10ms, in this case, the boost converter switch current limit must be higher than 6.27A.

    However, if the 1A peak time is only 100us-500us, a big aluminum electrolytic capacitor could added at output to buffer the sudden increased load current and the selected boost converter switch current limit could be smaller.

    So what's the 1A peak current lasting time?