Tool/software:
Hi Team TI,
I need to generate a biphasic current pulse as shown below.
I tried to use a improved Howland current pump for the same.
Below is the output waveform I obtained .It's waveform is completely different from my required waveform.
My circuit is given below.
May I know how to obtain the waveform as shown in the first image.
Hi Ron,
"A less complicated solution is to use a microcontroller to generate two outputs, one high for positive phase, the other high for negative phase. Run one output to Howland non inverting input the other to Howland inverting input. "
I simulated the above method.But my current waveform remains the same.My voltage waveform (VF1) looks like the
required current waveform.
Hari,
I made the PG run in separate phases, just 1us of overlap (optional). More dead time than high time (less than 50%)
Two cycles of operation over 800us
Hi Ron,
I simulated the file you provided.
I am getting slightly different waveform
Hari,
The red line says 150Hz. That makes this time be 1,000,000us / 150Hz = 6667us
Visually, most of the red line time is 0mA current. However the green horizontal arrow says this time is 100us
100us is not a majority of 6667.
Hari,
This simulates well minus the pulse counter and start button and optional end of stream indicator.
Pulse duration is set by dual linear taper PD potentiometer (10us to 500us). Frequency is set by another potentiometer, this control is inverse scale (time is linear through rotation [33.3ms to 6.7ms]). The simulation works best using "zero initial conditions"; that is why I "pre-charge" the storage cap instead of waiting for it to charge for the simulation. In reality the cap will charge up under 1 second.
For the counter, I'll let the logic team suggest chips(s) for that. Run 1 to 10 cycles
