it can be a shunt regulator, and there is even a circuit for its use as a switching regulator in the data sheet. To fully understand the 723 then is to fully understand low voltage linear regulators.

The circuit is centered around a TL431 programmable shunt regulator ... but it thrives on feedback. To make a voltage regulator from the LED circuit shown here, all you need to do is add a ...

The circuit has a shunt regulator, internal voltage and bias current generators, built-in power-on-reset and oscillator. The core is easily retargeted to any other CMOS technology with R-poly devices.