Hello there,
I'm totally new to SMPS design, this is my first attempt. The plan is to have a module with USB type C PD input that will power up DACs and preamps. There are 4 power supplies in this design.
Analogue PS consists of LT8582 as a boost converter and a inverting boost converter with LT3045-1 and LT3094 LDOs in VOIC mode (in the LT8582s' feedback loop).
Digital PS is two SEPIC converters delivering 5V (or any other low voltage). The LDO setup is the same.
I would greatly appreciate it if somebody could verify my design. Any tips and corrections are greatly appreciated!
Have a nice weekend
I'm totally new to SMPS design, this is my first attempt. The plan is to have a module with USB type C PD input that will power up DACs and preamps. There are 4 power supplies in this design.
Analogue PS consists of LT8582 as a boost converter and a inverting boost converter with LT3045-1 and LT3094 LDOs in VOIC mode (in the LT8582s' feedback loop).
Digital PS is two SEPIC converters delivering 5V (or any other low voltage). The LDO setup is the same.
I would greatly appreciate it if somebody could verify my design. Any tips and corrections are greatly appreciated!
Have a nice weekend
Your first schematic is ok. The second schematic does not look ok regarding PG and SHDN pins.
I have built a few of similar designs with LT8582 and LT30xx. Layout is the key to reach noise levels of LT30xx datasheets. VIOC is not very useful if you have a fixed output voltage. IME it just increases noise. All in all LT8582 is not my favourite as it seems to be too fragile for such an expensive chip.
Here is one of my designs ("SilentSwitcher XL").
I have built a few of similar designs with LT8582 and LT30xx. Layout is the key to reach noise levels of LT30xx datasheets. VIOC is not very useful if you have a fixed output voltage. IME it just increases noise. All in all LT8582 is not my favourite as it seems to be too fragile for such an expensive chip.
Here is one of my designs ("SilentSwitcher XL").
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To get actual USB PD support you will need an IC that communicates the USB PD capability and the corresponding acceptable profiles to compatible chargers or powerbanks. Last time I checked, most of the purpose built ICs that can be implemented without writing code were out of stock. Same thing for the LT8582 switcher IC and the ultra low noise regulators. I have a similar design basically ready to order, but I guess it will be a few more months of waiting.
Thank you for a detailed answer. You are right, I messed up the SHDN and PG pins on the second schematic.
Do I understand that coils in SEPIC and the inverting circuit should be on the same core (dual coil)?
What do you mean LT8582 is fragile? How it can break easily? Overload? Any other ICs that are nicer?
VOIC might be noisier since it makes the FB loop longer, true. I might redesign it to be omitted.
At least based on simulations coupled inductor (dual coil) has lower current swings at startup. But heating may be more of an issue if load current is high.
I don't exactly know what is the problem with LT8582. E.g. one of them burst with a bang while the board was idling with no load. Maybe oscillations or just bad chip. Luckily the LDOs survived.
If +/-15V@200mA is sufficient then LT3471 may be a better choice. I've never had any issues with it.
I don't exactly know what is the problem with LT8582. E.g. one of them burst with a bang while the board was idling with no load. Maybe oscillations or just bad chip. Luckily the LDOs survived.
If +/-15V@200mA is sufficient then LT3471 may be a better choice. I've never had any issues with it.