LM3150-250EVAL: Question of Voltage Drop on LM3150-250 EVM

Wayne Chen (ex FAE)

Part Number: LM3150-250EVAL
Other Parts Discussed in Thread: LM3150

Hi Sirs,

My customer reports a voltage drop issue on te LM3150-250 EVM with VIN = 24V, RFB1 reworking to 1.18kohm:

We can get 12V Vout with no load, however, the Vout drops to 11.2V with 2A load current (target is 7A). Vin is stable at 24V in this case.
Would you pls advise tips to identify the problem?

Thank you and Best regards,

Wayne Chen
05/07/2020

over 4 years ago

0 Timothy Hegarty over 4 years ago

TI__Guru 53082 points

Hi Wayne,

This is a COT controller that needs a certain amplitude of ripple at FB. By increasing the divider ratio to go from 3.3V to 12V out, the ripple on Vout was likely attenuated too much. Please review the ripple calculations in the LM3150 datasheet.

Regards,

Tim

www.ti.com/widevin

0 Wayne Chen (ex FAE) over 4 years ago in reply to Timothy Hegarty

Guru 15950 points

Hi Tim,

Thank you for your advise. Addition to the application note, should we follow up the Webench result to define the feedback resistance (191kohm, 10kohm in this case)?

Thank you and Best regards,

Wayne Chen
05/08/2020

0 Timothy Hegarty over 4 years ago in reply to Wayne Chen (ex FAE)

TI__Guru 53082 points

Hi Wayne,

Those feedback divider values seem fine. Just make sure the feedback network is located close to the FB pin and keep the FB trace short.

Regards,

Tim

Power management

Power management forum

LM3150-250EVAL: Question of Voltage Drop on LM3150-250 EVM