Tina:
It is possible to anticipate that various different smoke detectors use different chips!! I cannot be certain about the chip part number in the unit that I pried open. I had some reservation about opening the ionization chamber to look directly at the chip.

In looking at the data sheet you linked to I guess I connected to the equivalent of pins 9 or 10 (Horn Driver). You should experiment within your unit with a o-scope.

Michael Karas