Question about one of the circuits in LM399 datasheet

[opa627bm]

Hello everyone,
                     Can someone tell me what is the functionality of the 12k, 2k and 20k resistors in the circuit? They seems formed a voltage divider to prevent the output from the trimpot goes too low?

[T3sl4co1l]

They control the output voltage.  The trimpot is just that, a trimpot, not a wide range control.

Tim

[c4757p]

Trimpots have shit temperature coefficients. This arrangement allows good quality, fixed resistors to exert most of the control over the output voltage.

[quantumvolt]

The left divider 12/2 gives an output (6.95*(2/(2+12)) which is a bit less than 1 volt and has internal resistance a bit less than 2k. Adding the 20k in series increases the source resistance to some small 22k. The 100k trim and the 2M makes a 6.95 volt source with resistance a bit more than 2M (a hundred times greater than 20k). So the trim will be able to alter the summed voltage with around  1 %. The right side 2k buffers the op amp and is small in order to not disturb the balance of the op amp bias (the two inputs should see appr. the same DC resistance, hence the left side arrangement so-so balances the 22k feedback resistor).