Robin Williams Financially Protected His Kids ... With Strings Attached

Robin Williams protected his children by creating a trust, but he had the suspicions of a parent who worried the kids would squander the money when they were young.

TMZ has obtained Robin's trust ... which was created in 2009. Under the trust, his kids, 22-year-old Cody, 25-year-old Zelda and 31-year-old Zachary received money ... but in steps.

When each turned 21 they got 1/3 of the share. When they turned 25 they got half of what remained. When they turned 30 they each got their full share.

The trust was not dependent on Robin's death. The kids received their money, although Cody and Zelda have not been paid in full because of their age.

We do not know how much money was in the trust. We're told Robin had a significant amount of money outside the trust and his current wife, Susan Schneider, will almost certainly receive a significant amount.

As for how much Robin was worth ... there were estimates approaching $130 million in 2012. But in 2013 Robin did an interview saying he was on the verge of bankruptcy because of his 2 costly divorces.

Robin said at the time he was selling his $35 million estate to become solvent again.