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TPS55340: Power management forum

Part Number: TPS55340

御社製品のTPS55340のSS端子に、GRM155R61C223KA01D(村田製作所製チップコンデンサ:0.022μF)が搭載されています。

この部品をGRM033R61C223KE84D(村田製作所製チップコンデンサ:0.022μF)に変更した場合、静電容量は同じなのですが

DCバイアス特性が1.8V付近で容量が0.9%からー2.8%に小さくなっています。このことによって出力にどのような変化が出ると

考えられますでしょうか。お忙しいところ申し訳ございませんが、お教え願いますようお願い致します。

GRM155R61C223KA01D (Murata Manufacturing chip capacitor: 0.022μF) is connected to the SS terminal of your product TPS55340.

If you change this part to GRM033R61C223KE84D (Murata Manufacturing chip capacitor: 0.022μF), the capacitance is the same.

But, when the DC bias characteristic is around 1.8V, the capacitance is reduced from 0.9% to -2.8%.

What effect does the output have?

  • Hi Makoto,

    Until soft-start hits 1.8V, the soft-start voltage is clamping the error amplifier. This means duty cycle is limited as a function of soft-start voltage. For the TPS55340, when soft-start hits 1.8V, soft-start is complete and the error amplifier output is no longer clamped by soft-start, therefore you may see slight overshoot, but probably not much change as soft-start is already done. 

    Thanks,

    Richard