@http://www.ac-heatingconnect.com/how-thermostatic-expansion-valves-txv-work/

Above link indicates that condenser pressure or the inlet pressure to TXV also is a parameter in pressure balancing equation

TXV Pressure Balance EquationTXV
P1+P4 = P2+P3
P1 = Bulb Pressure (Opening Force)
P2 = Evaporator Pressure (Closing Force)
P3 = Superheat Spring Pressure (Closing Force)
P4 = Liquid Pressure (Opening Force)
However in all other literature including WIKI & Danfoss educational media in the above equation P4 is totally absent



...My question is this equation universal or is design dependent. By the look of the valve operation I beileve the former is true but why many others aren't involving condenser pressure