Part Number:LM5021
I am using the LM5021 in an isolated flyback circuit. 24V DC in and 16V out.
In order to ensure that the device starts up at a usable voltage I cannot use the internal regulator but instead I create a 9V supply (from a linear regulator, there is no start-up winding) and connect this to both VIN and VIN, i.e. the internal regulator is by-passed.
My question is what is the maximum permitted value of VCC?
The data sheet SNVS359E –MAY 2005–REVISED DECEMBER 2014 is contradictory:-
"All other pins to GND 7V" but this van't be true because Vcc is 8.5V nominal!
"VCC Output only of a linear bias supply regulator. Nominally 8.5 V."
"VCC Output only of a linear bias supply regulator. Nominally 8.5 V."
and later
"It is not recommended that the bias winding be connected to the VCC pin of the LM5021. Doing so can cause the device to operate incorrectly or not at all."
We ll I can repor tthat it works just fine with VIN=VCC=+9V from an external source. What I would like to know hoever is what is the maximum for Vcc so that I can tick a box in my circuit review.