the uc1846/7 family of control ics provides all of the necessary features to implement fixed frequency current mode...

Dual 500mA Boost/Flyback/Push-Pull DC/DC Controller, 8V-40V, 13.5V Output, SOIC-16

Dual ended 500KHz current mode PWM controller, -40C to 85C 16-SOIC -40 to 85

Dual 500mA Boost/Flyback/Push-Pull DC/DC Controller, 40V, 85°C, QCCJ Package
Boost/Flyback/Push-Pull DC/DC Controller, 2 Outputs, 40V, 500mA, 85°C, PLCC
Dual ended 500KHz current mode PWM controller, -40C to 85C 16-SOIC -40 to 85