BM2P121W-Z & BM2P131W-Z PWM DC/DC Converter ICs ROHM Semiconductor BM2P121W-Z and BM2P131W-Z PWM DC/DC Converter ICs provide an optimum system for all products, including an electrical outlet. The ROHM Semiconductor ICs have a built-in startup circuit that can tolerate up to 650V. The devices also have a current detection resistor as an internal device and provide a low-power consumption solution ideal for small power supply designs.