This circuit is from the datasheet of the famous [LTZ1000][1] voltage reference:

[![enter image description here][2]][2]

Can anyone explain in detail how the circuit works? Especially the 400 kΩ effect; what is the benefit of the 400 kΩ resistor?


  [1]: https://www.analog.com/media/en/technical-documentation/data-sheets/ltz1000.pdf
  [2]: https://i.sstatic.net/z2teZ.png