Why does this datasheet show an example with an input voltage outside its recommended range?
From IRS2453(1)D(S) datasheet:



\$V_{CC}\$ can be from \$V_{CCUV+}\$ to \$V_{CLAMP}\$.  There is an internal 15.6V zener diode to keep \$V_{CC}\$ clamped below 15.6V (14.6V to 16.6V).  

Under-Voltage Lock-Out Mode prevents the chip from turning on until \$V_{CC}\$ is above \$V_{CCUV+}\$ (10V to 12V).  As long as \$V_{CC}\$ > \$V_{CCUV-}\$ (8V to 10V), the chip will oscillate.  The \$V_{CC}\$ under voltage lockout hysteresis \$V_{CCUVH}\$ typically is 2V or \$V_{CCUV+}\$ - \$V_{CCUV-}\$ = 10V - 8V = 2V.  You are driving ac loads, which means the power lines are going to be susceptible to noise.  This is just a safety range for the power. 

\$V_{CC}\$ can range from (8V to 10V) to (14.6V to 16.6V), once the chip turns on.  All of the tests were done with \$V_{CC}\$ = 14V, but 15V makes perfect sense.  If \$V_{CC}\$ = 16V, it may be clamped or not.