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Original question:

LM5118: Design for Solar Panel and Lead-Acid Battery

LM5118: VCC tied to ramp

Colin Selfridge
Prodigy 40 points
Part Number: LM5118

Hi,

I was curious as to what the conditions are for tying the VCC pin to the ramp capacitor. The 12V, 3A output schematic on the datasheet seems to tie VCC to the ramp without a pull down resistor. However, when designing using the webench tool for 12V, 2A output VCC is just coupled to ground through a 1uF capacitor.

Thanks

  • 0
    TI__Guru* 76815 points
    Hi Colin,

    The RAMP pull up resistor is introduced to reserve a position on EVM such that additional slope can be produced, which will be the case of higher Vin conditions. Reducing the pullup resistor value will add more slope compensation. It is not always needed but having it will give you another freedom in selecting the power inductor and current sense resistor.

    Thanks,
    Youhao