LM5155: BIAS vs Input?

johny radio

Expert 1280 points

Part Number: LM5155

The datasheet of this part says:

It can operate with the input supply voltage as low as 1.5 V if the BIAS pin is greater than 3.5 V.

In the schematic, i can see BIAS. But i can't see "input". Where is input?

0 johny radio 3 months ago

Expert 1280 points

In The above schematic, bias and supply are wired together. Is there a different boost reference schematic where they are not wired together?

0 Moritz 3 months ago in reply to johny radio

Hi Johny,

The input supply voltage is Vsupply.

The bias pin is the supply of the IC.

If the IC is supplied by 3.5V, the input for the boost stage can go down to 1.5V.

The bias pin does not have to be connected to the Vsupply, it can also be connected to an external voltage source.

Best regards

Moritz

0 johny radio 3 months ago in reply to Moritz

Expert 1280 points

Where in the schematic is the input to the boost stage? What's the difference between the supply and the input?

+1 Moritz 3 months ago in reply to johny radio

Hi Johny,

Please refer to below. Vsupply (IN Boost) is the voltage that is going to be boosted.

Vbias supplies the IC. It has to be at least 3.5V. If it is supplied from external, Vsupply can go lower.

Best regards

Moritz

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