ltm4622a

Question

HI, 
 Is there anybody who can give me some clues on the questions below? Thanks in advance. 
 
 (1) The minimum output voltage of LTM4622A is 1.5V. Can it output 1.2V ?

(2) If we replace the 40.2k resistor with 60.4k, can Vout1 output 1.2V? 
 If so, what will be the possible problem with long-term use of 60.4k resistor under this condition?

NHara · Accepted Answer

Hi, 
 It is not recommended to operate outside of the datasheet spec. Depending on other settings, you may run into minimum on-time issues, issues caused by size of inductor ripple, and other unforeseen issues due to being outside of the datasheet spec. 
 I would recommend the LTM4622 for operating at 1.2Vo. It is very similar to the LTM4622A, and it is able to run at 1.2Vo.)

NHara · Answer

Yes, there are some internal differences between the LTM4622 and LTM4622A. From the block diagram on page 8 of both of the parts' datasheets, you can see the output stage components are different due to the different output voltage ranges. For instance, the internal inductor (1uH for LTM4622 and 2.2uH for LTM4622A) was chosen to optimize performance over the different output voltage ranges. Also, the voltage ratings of the internal components need to be taken into account. By using the LTM4622 above its suggested output voltage range, you may be violating the voltage rating of its internal output capacitors. 
 I would not recommend operating a module outside of its datasheet specs. Unforeseen issues and unwanted behavior may occur while operating outside of the specs.

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ltm4622a