LMZ14202H: The required input/output voltage difference spec of the LMZ14202H

Hello

I think that Webench provides a conservative design.

If you wish to use this device under the conditions specified, you will 

have to test it very carefully under all conditions of load and temperature, etc.

TI does not recommend ignoring a Webench design, unless the customer can guarantee

that their design is robust and meets all of their application conditions.

Thanks

Hello

From the data sheet we find that the minimum off-time is 260ns.  This will set your maximum

duty cycle according to your switching frequency.  

You may be able to use Webench to give you a design by lowering the switching frequency or using the

design equations in the data sheet.

Thanks

Hello

Some approximate calculations show that you would need a switching frequency of about 100kHz.

This would need an Ron of about 2Meg.  This value is too large and 100kHz is somewhat out of range

for this device.

This confirms that this device is not a good choice for these conditions.

Looking at Webench, it has created many different solutions for your conditions; I have attached one here.

Please use Webench to find a suitable device for your application conditions.

Thanks

WBDesign510.pdf

Hello

Equation 19 is used for minimum duty cycle operation.

I have attached the equation used for the drop-out calculation along with values from the 

internal parameters of the device.

Thanks

dropout1.docx