TPS40305: circuit is not regulating correctly under load

Viktorija Cecil

Part Number: TPS40305

Team,

Can you please help my customer with an implementation of TPS40305:

The circuit is not regulating correctly under load. I see your WEBENCH tool for the device but it is very limited since my MOSFETs and Inductor are not in the list of components for me to substitute. Also, the WEBENCH tool will not let me select >14V for VIN despite the DS indication that VIN MAX = 20V. Any assistance you can provide with design tools or spreadsheet calculators for this device could potentially expedite my efforts in identifying the necessary circuit changes. Any help you can provide is much appreciated.

Thanks

Viktorija

over 4 years ago

0 Gerold Dhanabalan - Online Design Tools over 4 years ago

TI__Genius 14455 points

Do you mean that the circuit is unstable or is it hitting current limit etc.?

The problem is that WEBENCH might not be able to find FETs that work at 20V Vin and is causing designs to fail at the current that you need.

Will send you the excel tool by email.

Regards,

Gerold

0 Peter James Miller over 4 years ago

TI__Guru 56825 points

Viktorija Cecil

Any information you can provide about what you mean by it is "not regulating correctly under load" would be helpful.

The TPS40305 converter runs at 1.2MHz with a 70ns minimum on-time for a minimum 8.4% duty cycle. For voltages 1.2V or less, that will limit the input voltage to no more than 14V. At higher input voltages the switching could be erratic as the converter needs to skip pulses to maintain regulation.

What is the output voltage?

Can you share the schematic here, or via e-mail?

0 Peter James Miller over 4 years ago

TI__Guru 56825 points

Viktorija Cecil

I am making this thread as "Waiting for Customer" while we wait for the details from the customer.

Power management

Power management forum

TPS40305: circuit is not regulating correctly under load