Is it common that a boost DCDC converter has an output voltage which is the same as the input voltage, when the switching does not occur?

I'm reading the TPS55340EVM-017 datasheet. In the caption for Figure 14, it is described that the EN voltage goes low and the output voltage ramps from 24 V to Vin. I'm curious why the output voltage does not decrease to zero.

Also when the switching does not happen, isn't there limitation in the output current?


1 Answer 1


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Because the diode (D in the schematic above) in the boost converter allows current to flow from input to output. When you drop EN, the device stops switching and thus stops boosting but the voltage will not drop any lower than Vin (save for a diode Vf) because of said path is always available.

  • \$\begingroup\$ Thank you for the clear answer. I should have thought what 'non switching' actually means. When the switch is open, the result is obvious. \$\endgroup\$
    – Nownuri
    Nov 20, 2018 at 7:56

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