LM46001PWPEVM: lm46001

Mike Berry1

Part Number: LM46001PWPEVM
Other Parts Discussed in Thread: LM46001

Im using the default webench design for the LM46001 (500khz 5 v out) and have produced a pcb. I have not placed the Capacitors really close to the IC but nearby. I am not getting the voltage regulation I expected with omnly 4.49v out not 5v. On load (300mA ) the voltage collapses. If I change the Rfb to 230kohm (not 255kOhm) I get a better span of voltage with loads. But this seems to be a case of positioning or suffer the sensitivity issues. Has anyone found this before?

Mick

over 6 years ago

0 Timothy Hegarty over 6 years ago

TI__Guru* 75462 points

Hi Mike,

Please send the schematic and layout.

Regards,

Tim

0 Mike Berry1 over 6 years ago in reply to Timothy Hegarty

Prodigy 30 points

0 Timothy Hegarty over 6 years ago in reply to Mike Berry1

TI__Guru* 75462 points

Hi Mike,

It is imperative to place the feedback resistors close to the FB pin of the LM46001, particularly given their high impedance in this circuit. More specifically, the lower feedback resistor should connect between FB and AGND (pins 9 and 10) and the FB trace should be as short as possible. This mitigates the possibility of noise pickup. If this is not possible with your circuit layout, try reducing the resistances by an order of magnitude.

Regards,

Tim

0 Mike Berry1 over 6 years ago in reply to Timothy Hegarty

Prodigy 30 points

Thank you I will try this and next iteration reposition parts

Mick

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LM46001PWPEVM: lm46001