Value of INTVcc when input is 5V

Hello,

the internal LDO will regulate towards 5.3V when enough headroom is available:

When Vin is lower than 6V the INTVCC voltage depends on the drop and the operating current, as you assumed already.

Thank you Marcus,

Sorry I have not replied earlier but I was on vacation last week.

So does the INTVcc need to be stable? I am now thinking that this device only requires the LDO to provide the voltages it requires when the Vin exceeds 6V, the output of the LDO, does not need to be regulated, and the LTC3833 will function happily within it input range.

I do not have any voltage other than 5V that I can take power from, although I can sneak a few mA from a 12V supply that is designated for other uses. There will be 18 of these devices of varying power to provide a power solution to a ultrascale+ SOC

Thank you Marcus,

Sorry I have not replied earlier but I was on vacation last week.

So does the INTVcc need to be stable? I am now thinking that this device only requires the LDO to provide the voltages it requires when the Vin exceeds 6V, the output of the LDO, does not need to be regulated, and the LTC3833 will function happily within it input range.

I do not have any voltage other than 5V that I can take power from, although I can sneak a few mA from a 12V supply that is designated for other uses. There will be 18 of these devices of varying power to provide a power solution to a ultrascale+ SOC

Hello,

the part will work with 5V as well, at least we have stated it to operate from 4.5V onwards. I assume the INTVCC value is not tested for voltages beyond 6V. So go ahead. What are your power requirements, Vout etc?

Most are 2-4A, a variety of voltages from 0.9 to 3.3V but 2 will be 12.5A 0.85V. Transistors are GaN EPC devices. The LT-Spice simulation looks good. I am wondering if I need to connect to the INTVcc eternally other than to add cap as the input 5V can drive the signals nominally connected to it and that is stabilised. It could be noisier compared to a LDO output, but only if the LDO is regulating.