who provide VDD of bandgap??

[gwdbsuccess]

figure as shown below


I want to use bandgap in DC/DC controller
before normal operation,the reference voltage have to be provided first
the common VDD maybe: VDD+-10% or 3~12V

but the commercial product has very large range of Vin
ex:LT8300 Vin:6~100V
View attachment 8300f.pdf
have any circuit provide bandgap's VDD by transferring Vin???

plz help me with this problem.m(_ _)m

 

[dick_freebird]

For the bandgap to be accurate across that range,
you want to limit the portion of that range that it
"sees". Like perhaps a "poor-boy LDO" that comes
up quick and then plateaus as VIN rises, making a
"VDD_int" on-chip supply (if this is an integrated
design, as the schematic style implies). A shunt
reference with a trickle feed is good here, either
zener based or stack-of-diodes based; the temp
variation would be not-good but can be lumped
with the bandgap core tempco for trimming /
targeting. The on-chip LDO will greatly improve
DC PSRR and the right kind can really help HF
PSRR too.

This schematic lacks a startup circuit, so don't
despair if your simulations fail.

 

[gwdbsuccess]

dick_freebird

Thanks for your explanation !!m(_ _)m