4 Hz h bridge inverter, using pwm

Hello,

I am trying to create a 4 hz square wave inverter (alternating current). It needs to be around 36 volts, and will only pass a few tens of mili-amps (20-100 max)

I would think there would be a H-Bridge inverter chip that could do this...perhaps driven by pwm using a tl494 or 555 or other similar timer. I know there are alot of monolithic chips out there that are for motor controllers and the such, but do not know if they would be suitable for such a purpose. Many of the ones I have come across are run by changing the duty cycle, which means I would have to create some cleaver circuit which would change the duty cycle 4 times a second in order to control the "inverter" frequency, or use a micro controller, which I would Really like to avoid.

Does anybody know of any such simple solutions?

You have to feed a 4 Hz square wave to the H-bridge. What has the problem to do with PWM?

I assume this would have to be a pnp high side and npn low side h bridge?

Many of the ICs I have found have duty cycle which controls their fets. Can anyone suggest a model number that I could use a pwm IC with?