Hi, I would like to design a 1V, 2A dcdc power supply with the MPM3551C. Is it possible to adjust the output voltage to 1V when the Vin is 16V? From the minimum on time it seems not, is it correct ?
Hi @francesco.cassarini ,
The MPM3551C has 65ns min on time, but that’s the typical value. There is no minimum value listed for that spec, so it can theoretically support 1Vout @ 16Vin. The efficiency chart shows that it can support 3.3Vout @ 36Vin with fsw = 2.2MHz, which is about 41.7ns on-time:
Nevertheless, I can help you select a module that can support 1Vout @ 16Vin with written-out specs. Most likely we would need a module that uses constant on-time control. Do you have any voltage/current requirements to take in account of transients?
Thanks,
Rubas
Thanks for your reply,
The target rail is 1.0V from 16V input, with 1.5A nominal load. At the moment we do not have a detailed transient profile from the load. As a first assumption, please consider a load step from 0A to 2A, with output voltage remaining within ±3% of 1.0V. Also please consider automotive qualification.
Another option is to keep the MPM3551C but having two DCDC stages . For example 1st stage 16 to 5V, 2nd stage 5 to 1V, will be this option more efficient compared to the 16 to 1V solution? Do you have other efficiency charts for Vout lower than 3.3V?
Thanks
Hi @francesco.cassarini ,
I was going to recommend the MPM3632S, which uses constant on-time control method. However, now that you mentioned automotive use-case, it’s better to use a current mode control method to make sure the frequency is consistent to prevent cross-talk in the automotive system.
Yes, generally a two-stage DCDC is more efficient than dropping from 16V to 1V in a single-stage. I will look into further to see what we can provide for single-stage and two-stage.
Thanks,
Rubas