Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.

When designing an LM2674-based inverting switching regulator to deliver -15 V output, what is the allowable maximum input voltage?

April 26, 2017allowable deliver designing inverting output regulator switching v

0

Posted

When designing an LM2674-based inverting switching regulator to deliver -15 V output, what is the allowable maximum input voltage?

1 Answer

0

Posted

When a buck switching regulator is used to develop a negative output voltage from a positive input, the maximum input voltage becomes limited by the value of the negative output. For example, if the output voltage is -15V, and the Maximum Operating Rating for the input voltage is 40V, then in the application the maximum input voltage becomes (40V-15V) or 25V. The reason for this limitation is that the negative output voltage is normally seen at the ground pin of the IC, so the IC total supply voltage is the sum of the magnitudes of the input and output voltages. See Application Note AN-1157 “Positive to Negative Buck Boost Converter Using LM267X Simple Switcher Regulators” for more information. The issue is noted in the “IC Device Ratings” section.