DC converter output voltage

DC-DC converter output voltage is adjustable

Generally speaking, the output voltage of the DC-DC converter is fixed, like the picture above,

As long as a simple circuit is added to this diagram, the output voltage can be controlled through Vc.

Vout - Vr = (Vfb - Vr) (R1+R2)/R2

R1 = 20 kΩ and R2 = 10 kΩ
VOut – Vr = 3(Vfb – Vr)
VOut = 3 Vfb – 2 Vr(4)
Vr = 2 VR ef – VC

VOut = 3 Vfb – 4 VRef + 2 VC

3 Vfb = 4 VR e

VOut = 2VC

U1=0.8V, select R7=10 kΩ, R8=3.16 kΩ
Vref=0.6V

In this way, C1 reduces the output of U2 and ensures the stability of the U1 feedback loop.