LM2831: Overshoot of output voltage

Hi User,

Thank you for your question.

Can you share the schematic of your application?

In order to better understand your problem, it would be useful if you could provide me the waveforms of VIN, VOUT, SW and FB showing the SAG event and a zoom on the output overvoltage.

Thanks,

Stefano

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

Hi User,

Thanks for the additional data.

I think that the problem is the following one: when VIN is low the device goes in an high duty cycle operation, in order to keep VIN ~ VOUT.

After that, the rising slew rate on the input is too fast for the control loop of this device, that has a delay before reducing the duty cycle, causing the overshoot on the output voltage.

I think that it would be difficult to eliminate this problem since LM2831Y (500kHz switching frequency) is not optimized for a fast response.

Moreover, LM2831 is an obsolete device and I wouldn't advise it for new products.

I'd suggest to take a look at new and more competitive products, for example TPS62825 (high performance) or TLV62569 (cost optimized).

Thanks,

Stefano

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).