My I is a constant source of 10 mA from Vsupply of 50V, so my R(load) can max at 5k at 10mA.
I(load) is going both directions.
My I(source) is constant, but I(load) is changing with varying R(load), why is that?
Thank you.
my voltage source is 50V, supplying a constant current mirror of 10mA, which is then feed to h bridge.
So Vsource could >5V if Rload>500, and Q5 and Q6 will switch on regardless of V1 V2?
My Rload will definitely > 500, while V1 and V2 are 5V. So how should I implement h bridge in my situation?
Best Answer
The best way to see what happens is for you to plot the base current of Q5 and Q6 as the voltage on the emitters (Q5, Q6) varies.
You will see that the base current changes as the emitter voltage changes. The only place that base current can come from is the current source.
Any current that is consumed by the E-B junctions of the transistors is not available to be sent to the load.
You also have other potential issues: if the magnitude of V1 and V2 isn't high enough, Q5 and Q6 will never turn off. But you don't mention the magnitude of the voltage sources, so I'm just warning you about the potential issue.