ISL6551 is a zero voltage switching (ZVS) full-bridge PWM controller designed by Intersil for isolated power systems. This part implements a unique control algorithm for fixed-frequency ZVS current mode control, yielding high efficiency with low EMI. The two lower drivers are PWM-controlled on the trailing edge and employ resonant delay while the two upper drivers are driven at a fixed 50% duty cycle. This IC integrates many features in both 6x6 mm2 QFN and 28-lead SOIC packages to yield a complete and sophisticated power supply solution. Control features include programmable soft-start for controlled start-up, programmable resonant delay for zero voltage switching, programmable leading edge blanking to prevent false triggering of the PWM comparator due to the leading edge spike of the current ramp, adjustable ramp for slope compensation, drive signals for implementing synchronous rectification in high output current, ultra high efficiency applications, and current share support for paralleling up to 10 units, which helps achieve higher reliability and availability as well as better load regulation.
The ISL6551 is a ZVS full‑bridge PWM controller designed for isolated power applications. It provides high‑speed PWM up to 1 MHz, programmable soft‑start, resonant delay, and current‑share support for up to ten units.
Key features include a precision bandgap reference, adjustable dead‑time, leading‑edge blanking, and built‑in over‑current and short‑circuit protection. The device is offered in 6 × 6 mm QFN and 28‑lead SOIC packages and is suited for telecom, datacom, and high‑end server power supplies.
| PWM Frequency | up to 1 MHz |
|---|---|
| Supply Voltage Range | -0.3 V to 16 V |
| Unity Gain Bandwidth | 10 MHz |
The device can operate from –0.3 V up to 16 V on VDD, VDDP1 and VDDP2.
It supports high‑speed PWM operation up to 1 MHz.
The start‑up threshold (VDDon) is specified as 9.16 V.
The IC is offered in a 6 × 6 mm QFN package and a 28‑lead SOIC package.