As stated in the data sheet under the Absolute Maximum ratings the MAX15158 can operate from -40ºC to +125ºC. The absolute maximum temperature rating of +150ºC is for Junction Temperature.
MAX15158
Production
MAX15158/MAX15158A is a high-voltage multiphase boost controller designed to support up to two MOSFET drivers and four external MOSFETs in single-phase...
Datasheet
MAX15158 on Analog.com
As stated in the data sheet under the Absolute Maximum ratings the MAX15158 can operate from -40ºC to +125ºC. The absolute maximum temperature rating of +150ºC is for Junction Temperature.