nl2 - ATo

Judging by his stack size I think your opponent is definitely a bad player against which your TPTK has value. Apart from that, most strong hands have the tendency to check here and try a check/raise more often then not.

When he donks ~half pot I think his most likely holding is a weak made hand like weak Tx (T8, JT), 9x, maybe 88-77 or draw which can range from good flush draws (QJ :diamond:) to weak gutshots like 86. Knowing this and taking into account his stack size I think raising for value in an attempt to get all in on the flop is your best option, which you did. I think your raise size is also fine. After he 3bets you just continue with your plan of getting it all in against a range we have already decided we are ahead off.

Nh, wp!

Pretty much exactly what Manu said. His donking range has a ton of medium strength hands and draws in, when he raises all in his range does narrow but we're still ahead a large percentage of the time as he can have all sorts of draws and Tx