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LM2623: Controller selection help

Matt Lang
Intellectual 540 points
Part Number: LM2623
Other Parts Discussed in Thread: LM2621, LMR61428

Hello,

I was hoping I could get some help choosing the right TI part. I need a boost converter for a 2cell AA battery application.

Vin min = 1.8

Vin max = 3.1

Vout = 8V

Iout max = 200mA continuous 

Ambient temp max = 35 deg C

I was looking at the LM2623A, which seems like it can achieve this and it seems to be available to purchase at higher quantity right now, which is a difficult task these days. But wanted to see what other options TI has. I tried Web bench tool, but that didn't really turn up any results.

If LM2623A is the best option, I had a question about the Vdd pin.

  1. The datasheet says the Vdd pin can have a maximum of 10V, but the recommended operating conditions say 5V max. Can I power Vdd with my 8V output? I don't see any application notes with example circuits with Vout higher than 5V. Or will I have to regulate by 8V down to 5 to power Vdd?

  • +1
    TI__Expert 5180 points

    Hi Matt,

    For such application and with high quantity stock, I think LM2623 is the best option. LM2621 is suitable as well, but it is relatively old chip too.

    For your question, if Vin in your application is stable, you can connect these pins to Vin or you can use sch below by adding a zener diode or use divider resistor to power these pins. The voltage at these pins do not need to be very precise.

    Best Regards,

    Eric Yue

  • 0 in reply to Eric Yue
    Intellectual 540 points

    Thanks Eric! I will do just that.

    Just to make sure I consider all options. Did you have better/other options that are not in stock currently?

  • 0 in reply to Matt Lang
    TI__Expert 5180 points

    Hi Matt,

    LMR61428 is suitable as well, but out of stock. There are not many options, because input voltage is low to 1.8V and output current is not very small.