Hi:
I am trying to figure out the total current drain. LTSpice says 140mA and Paul Malvino's
electronic worksheet says 417 mA (http://malvino.com/).
I would think that the formula should be Idrain = Ibias + Iavg + ICQ.
Ibias = (Vcc - 1.4 ) / (Rb1 + Rb2) = (20V - 1.4V) / (180Ω + 180Ω) = 50mA
Isat = Vceq / RL = 10V / 10Ω = 1A
Iavg = Isat / π = 1A / 3.14 = 318mA
Given that ICQ = Ibias as long as diodes and transistors are matched.
∴ Idrain = 50mA + 50mA + 318mA = 418mA
but why is LTS different?
David
I am trying to figure out the total current drain. LTSpice says 140mA and Paul Malvino's
electronic worksheet says 417 mA (http://malvino.com/).
I would think that the formula should be Idrain = Ibias + Iavg + ICQ.
Ibias = (Vcc - 1.4 ) / (Rb1 + Rb2) = (20V - 1.4V) / (180Ω + 180Ω) = 50mA
Isat = Vceq / RL = 10V / 10Ω = 1A
Iavg = Isat / π = 1A / 3.14 = 318mA
Given that ICQ = Ibias as long as diodes and transistors are matched.
∴ Idrain = 50mA + 50mA + 318mA = 418mA
but why is LTS different?
David
Attachments
-
2.2 KB Views: 15