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I have used LNB controller TPS65233 in my design. Input is 5.5V and Output: 13/18V. I am seeing access current drawn by the circuit when I give 5.5V input to the circuit and no load is connected to the output. Manually I have checked and there is no short seen on the circuit.

Also, When I connect the input supply and remove. Input supply rail is showing short with the ground for some time. EVB schematic for referance

Bimpelrekkie
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ABSTONE
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  • 1) include a link to the datasheet 2) how much current do you expect and 3) how much current is actually flowing? – Bimpelrekkie Feb 11 '21 at 10:41
  • 1) Link: https://www.ti.com/lit/gpn/tps65233 2) expected current: Less than 2.2A 3) For short period of time I checked, Till 5A it is drawing – ABSTONE Feb 11 '21 at 10:49

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What you seeing is probably the startup transient for charging the capacitors. It is possible that the input is starving and the regulator goes out of its operational parameters. Check with a scope the voltage on the chip input pin, if you see some oscillation this is the problem.

Also, have you checked with some load (even a simple resistor) attached? many regulators have issues without load since it's needed for stability.

If this doesn't help you should ask on the TI E2E forum posting your circuit layout, the TPS switchers are really sensitive to that, in my experience. The recommended layout in the datasheets is usually something like ``do it this way or it doesn't work'' if you haven't experience with the part.

Lorenzo Marcantonio
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