There is a CONTROL signal turnoff configuration: Soft Off (with Sequencing) or Immediately Off. You can use this configuration to choose a desirable behavior.
For more FAQ please check the following document.
UCD90xxx Family Frequently Asked Questions and Answers
UCD9090 UCD9090A UCD90120 UCD90120A UCD90124 UCD90124A UCD90160 UCD90160A UCD90240 UCD90320 UCD90320U