I am looking for a simple and inexpensive way to replace 12V 12mA piezo buzzer with 1.8~3V 50~80mA vibration motor, something like VC1034H025L. The piezo is driven by 30ms pulses at intervals varying from 570ms down to nothing (i.e. continuous 12V). Note that the actual output is open collector. I have no access to switching element, so I can either assume it does not support much more than 12mA or do some destructive testing (which I'd rather avoid).
Here are some options I've considered:
Option 1: DC-DC regulator, like AP62200. Problem - input capacitor will most likely draw much more than 12mA on start-up. Also these are designed to switch on/off by enable pin, not crude input power application.
Option 2: LDO, like AP7370. The problem is that this will not reduce current, plus a lot of heat to dissipate.
Option 3: 12V capable timer (like NA555) configured for fixed PWM. Problem - while this can reduce median voltage down to 3V, the actual voltage amplitude will still be 12V, and I am not sure tiny motors will be happy with this.
Option 4: boost OC output current capacity by external switch, somehow. Then use either of the options 1-3 above to drive the motor.
Which of the options above would you recommend? Or maybe there is much better solution?