The retry count is reset whenever the rail stays above the POWER_GOOD threshold for a TON_MAX_FAULT_LIMIT amount of without having a glitch. If TON_MAX_FAULT_LIMIT is set to 0, 4 seconds are used for the time.
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