I want to have a +-12.0V square wave output from an opamp fed from a 3.3 and 5V power supply. The signal is 2.5kHz with a low duty cycle of 3-10% generated by an MCU. Peak voltage at both ends need to be within 0.1V from +-12V. The load I am driving is 1kOhm so max 12mA. The slew rate requirement is 20V/us.
I have have tried a 5V to +-12V DC/DC converter as well as chargepump a. Given the low load I would think a chargepump is the most econimical. Using rail to rail opamps gave me 11.9V but I have never found an opamp with high enough slew rate. Meaning the rail to rail opamps seemed to0 slow.
Then I have searched for ‘trimmable’ charge pumps at say +-12.5V that would drive a faster opamp with a 0.5V output drop but have just not found it.
Was just wondering if you guys could help me with this. My situation is just easier with a more accurate 12V output. Even 11.9 has some downsides. Thanks
EDIT: Built the circuit per first answer. It works great!. Albeit the output is inverted. I solved this by modifying the circuit. Removed the inverting transistor for the +12V and added a second inverting transistor for the -12V side. But other than what I had expected, the circuit became clearly 'slower' in the second, non-inverting case than it was in the inverting case per the first answer.
I learned (by doing) that switching at 3.3V is slow and at 12V it is fast. What I do not understand is why the transistor M22 that I added makes the circuit slower. It is switched at 12V. What can I do to make my signal faster? (note that I simulate at 1Mhz and will build at 2.5kHz).
Probably better way to switch a -12V signal with at the inverse of a 3.3V signal than what I have done. Help appreciated!!