Petr Sladek st. sk. 107 10.11.2002 ================ nejmensi Rload: ================ bez zateze: Uout se zatezi: kUout; k = 1-(max_%dV/100); max_%dV=1%. delic: U o---+ | Ϋ Rupper (Ra1,2; Ra) | +---o Uout | Ϋ Rlower (Rb1,2; Rb) | GND o---+---o GND Ri = Rupper||Rlower. Ri Uout o---[===]---+----o kUout | Ϋ Rload | GND o-----------+----o GND kUout <= (Uout*Rload)/(Rload+Ri) /Uout \_________ _________/ | >= nez Umin = kUout k*Rload+k*Ri <= Rload k*Ri <= Rload*(1-k) kRi<=Rload(1-k) kRi/(1-k) <= Rload ΙΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝ» Ί kRi (1-max_%dV/100)Ri Ί Ί Rload >= -------- ;= ------------------ Ί Ί 1 - k max_%dV/100 Ί ΘΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΌ protoze Ri = Ra*Rb / (Ra+Rb) a U-Uout = U* Rb/(Ra+Rb) Uout = U-(U*Ra/(Ra+Rb)) kRi/(1-k) <= Rload z cehoz vyplyva: Ri <= Rload*(1-k)/k potom Ra*Rb ------- <= Rload*(1-k)/k (Ra+Rb) Uout = U(1- Ra/(Ra+Rb)) Ra Uout = U (1- -------- ) (Ra+Rb) Ra 1-(Uout/U) = ------- rozsirime Rb/Rb: Ra+Rb Ra*Rb Rb*(1-(Uout/U)) = ------- { <= Rload*(1-k)/k } (Ra+Rb) Rload*(1-k) Rb*(1-(Uout/U)) <= ----------- k Rload*(1-k) Rb <= -------------------- k*(1-(Uout/U)) U = U1 Uout = U2 Rload = Ri k= 1-(max_%dV/100), d= max_%dV/100 = delta_max/100 ΙΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝ» Ί Ri*d U2 Ί Ί Rb <= ------ / (1- ---- ) Ί Ί 1-d U1 Ί Ί Ί ΘΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΌ NOTE: U2 je vystupni napeti BEZ zatizeni U2 = U2req * (1+d) ============================================================================= addenum: ------------- proc Ri = Rupper||Rlower (=Ru||Rl) 1) Uout = U*Rl/(Ru+Rl) 2) Ri = dUout/dIout 3) dUout = U*(Rl/(Ru+Rl)) - U*((Rl||Rload)/(Ru+Rl||Rload)) dIout = U*((Rl||Rload)/(Ru+Rl||Rload)) / Rload dUout = U*((Rl/(Ru+Rl)) - ((Rl||Rload)/(Ru+Rl||Rload)) ) ( (Rl/(Ru+Rl)) - ((Rl||Rload)/(Ru+Rl||Rload)) ) Ri = ============================================== Rl||Rload -------------- Ru+Rl||Rload ---------------------- Rload 1. Ru+Rl||Rload: Rl*Rload Ru*Rl + Ru*Rload + Rl*Rload Ru+Rl||Rload = Ru + -------- = ------------------------------ Rl+Rload Rl+Rload 2: Rl||Rload -------------- / Rload = Ru+Rl||Rload Rl*Rload -------- Rl+Rload Rl =============================== = ----------------------------- Rl*Ru + Ru*Rload + Rl*Rload Rl*Ru + Ru*Rload + Rl*Rload ---------------------------- Rl+Rload 3. - ciatel: ((Rl||Rload)/(Ru+Rl||Rload)) ) = Rl*Rload -------- Rl+Rload Rl*Rload =============================== = ============================ Rl*Ru + Ru*Rload + Rl*Rload Rl*Ru + Ru*Rload + Rl*Rload ---------------------------- Rl+Rload Rl 4. jmenovatel: ----------------------------- Rl*Ru + Ru*Rload + Rl*Rload Rl Rl*Rload ----- - --------------------------- Ru+Rl Rl*Ru + Ru*Rload + Rl*Rload Ri = =========================================== Rl ----------------------------- Rl*Ru + Ru*Rload + Rl*Rload Rl^2*Ru + Ru*Rload*Rl + Rl^2*Rload - Ru*Rl*Rload - Rl^2*Rload ---------------------------------------------------------------- (Rl*Ru + Ru*Rload + Rl*Rload)(Ru+Rl) Ri = ================================================================== Rl ----------------------------- Rl*Ru + Ru*Rload + Rl*Rload Rl^2*Ru ---------------------------------------------- (Rl*Ru + Ru*Rload + Rl*Rload)(Ru+Rl) Ri = ================================================== Rl ----------------------------- Rl*Ru + Ru*Rload + Rl*Rload ΙΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝ» Ί Ί Ί Ri = Rl*Ru/(Ru+Rl) Ί Ί Ί ΘΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΝΌ