How is LR745 start-up regulator IC grounded?

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grizedale

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Figure 3, page 5 of the LR745 SMPS startup regulator shows it being grounded to the VREF pin of the UC3844 PWM controller IC....

...But that is not ground....so how is it grounded?

...surely "ground" means "ground"?


LR745 DATASHEET:
**broken link removed**

UC3844 DATASHEET:
http://www.ti.com/lit/ds/symlink/uc3844.pdf
 

Why do you think, the IC must be grounded? The net connected to the GND terminal must be able to sink a few mA. The reason for using this circuit is clearly explained in the datasheet.
 
FvM:

I understand the connection on fig 3, page 5 perfectly well...its just that the UC3844 datasheet gives no suggestion that prior to start-up, there is a conductive path to ground via the UC3844's VREF pin.

.....there has to be such a path, for the LR745's current to flow through.....and for the biasing of all its internal circuitry.
 

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