Other Parts Discussed in Thread: LM339, OPA462, TINA-TI
Hallo, I am trying to create an high voltage, high gain level shifting circuit.
This should be able to raise the waveform's amplitude to an higher level.
I've chosen the OPA454 to do the job, in its non-inverting amplifier configuration, but I'm experiencing some issues during my tests.
My needs are as following: given a digital input (different cases, from different MCUs, so 3.3 to 5.0 volts), square wave PWM, 50% duty cycle, variable frequency (1 kHz to 200 kHz, user selectable) and providing a source of 100VDC (10-100V, user selectable), I would like to have , as output, a PWM which have to be identical in the waveform (frequency, duty cycle, square shape), but with the sample amplitude as fed by the source (so 10-100V, as decided by the user).
The input voltage is varied externally to the op-amp, the same for the frequency and the DTC (which are controlled by the MCUs).
The desired output current doesn't exceed 40 mA.
I thought that it was simply to accomplish because I've previously and successfully done a similar thing with an LM339 (with lower voltages as a source, of course) but the OPA454 has the E/D + Status pins that I can't figure out how to manage correctly (if those are required).
The main, and dangerous, issue I have is the identification of the pin 1: there is NO dot on my SOP8 packages (Texas Instruments original op-amps)!!! On the chip there is a vertical line followed by the chip name, the brand (TI) and some other text.
The second doubt I have is related to the use of the pull-up resistor (1 MOhm, as per the specifications on the datasheet), between the V+ and the Status pins...
Finally the E/D (Enable/Disable) feature: is it mandatory? I've read, on the datasheet, that these pins can be left floating/unconnected...
Last, but not least, at the output, I need to connect an inductive load which has - as expected - huge back-emf spikes (this is by design and these spikes has NOT to be suppressed), so my concern is not to damage the OPA454 with such spikes.
Any help will be appreciated a lot, thank you in advance to everyone.
Fabrizio, Rome - Italy
fabrizioricciarelli@gmail.com
P.S.: I'm not an electronic engineering, only an enthusiastic hobbiest, dedicated to the alternative energies research