Intersil Active Clamp PWM Controller Simplifies Isolated DC-DC Converters
Intersil Corp. introduced a new current mode PWM controller that simplifies design through feature integration and reduced component count. In addition, the ISL6726 improves circuit reliability through a unique duty cycle clamp feature that reduces voltage stress on external components. The device is well suited for applications that require isolated active clamp forward and asymmetric half-bridge converter topologies, such as power systems in telecom and datacom equipment.
To provide improved reliability, the ISL6726 incorporates adjustable peak current limit as well as average current limit protection. The device includes both types of protection to ensure the output current is always within a safe operating range. The average current limit provides stable overload operation in applications requiring parallel or redundant converters and constant current applications such as battery chargers or LED drivers. For improved reliability in synchronous rectifier applications, the controller protects the switching components by clamping the minimum duty cycle. This prevents large negative output inductor currents during load transients.
For higher power applications, the ISL6726 provides a flexible and scalable solution that easily lends itself to design re-use. The ISL6726 includes a bi-directional synchronization option with 180° phase shift that enables interleaved topologies. Interleaving reduces RMS input current and simplifies thermal management. The controller also includes soft-start and soft-stop functionality, limiting electrical stress during the start-up and shut-down process.
The controller supports design of the active clamp reset topology that improves conversion efficiency in applications requiring a transformer isolated dc-dc converter. The ISL6726 further improves efficiency by providing precise duty cycle and deadtime control, enabling designers to use smaller power components to minimize board space.
The ISL6726 is available now in a 20-pin QSOP package, and is priced at $2.60 each in 1,000-unit quantities.
