Energiaallika jaoks: E1 I 1-E 6 I 6 + E5 I 5 =2(-1 )-11(-3 ) +12=33 Tarbija jaoks: I 21R1 + I 22R 2+ I 23R 3 + I 24R 4 + I 25R5 + I 26R6 =¿ ¿ 12+ 42+91+ 11+41+ 91=33 33 = 33 3. Arvutada vool I5 ekvivalentse generaatori meetodil Lihtsustatud takistuste skeem: 4 1 3 2 R2R1 22 Rg = R 3 + R6 + R 1+ R 2 R 4 1+1+ = (2+2 1 3 ) = =0,75 R R 22 4 R 3+ R 6+ 2 1 + R4 1+1+ 2+2 +1 R 1 + R2 6 E g=3 -2 leiame 3 ilma R5 ja E5
inverting input has a low enough impedance that the current is negligible. This will allow us to examine the inverting input only. Figure 9.2 shows the effect of input resistance, Ri, from the inverting to noninverting inputs. If we assume that the input resistance is equal to the typical value, 3 MW, then the opamp output equation looks like this: R1Ri + R2Ri Vo = R1Ri + R2R1+ R2Ri + R1Ri Av Figure 9.2 Opamp input resistance. 216 Analog Interfacing to Embedded Microprocessors If Av is very large, then the /AV term goes to zero, the Ri term cancels out, and the result is equal to the ideal equation. So the effect of input resistance is dependent on the open-loop gain of the opamp.
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