The MAX22256/MAX22258 integrated primary-side controllers and H-bridge drivers for isolated power-supply circuits feature a precision on-board oscillator, protection circuitry, and internal MOSFETs to provide up to 650mARMS of current to the primary winding of a transformer. These devices feature an internal 450kHz (typ) oscillator and can also be driven by an external clock to synchronize multiple devices and control EMI. An internal flip-flop stage guarantees a fixed 50% duty-cycle to prevent DC current flow in the transformer as long as the clock period is constant.The MAX22256/MAX22258 operate from a wide single-supply voltage range from 5V to 36V and include undervoltage lockout for controlled startup. Break-before-make switching is integrated to prevent cross-conduction of the H-bridge MOSFETs. A resistor-adjustable overcurrent limit allows primary-side limiting of load currents on the transformer’s secondary side and thermal shutdown circuitry provides additional protection against excessive power dissipation.The MAX22256A features a 30ns (typ) dead time for conventional H-bridge switching topologies. The MAX22256B/C feature a fixed dead time of 60ns (typ) and 100ns (typ), respectively, and are optimized for the zero-voltage switching of an LLC topology. The MAX22258 features a resistor-programmable dead time and a synchronized clock output (CLKO).ApplicationsIsolated Motor Drive Gate Power SupplyIsolated +24V PLC Field Supply