Intersil Unveils ISL88550A Synchronous PWM Controller

Intersil Corp. (Milpitas, CA) unveiled its new ISL88550A device, which integrates a synchronous buck, pulse-width modulated (PWM) controller to generate VDDQ, a sourcing and sinking low-dropout linear regulator to generate VTT, and a 10 mA reference output buffer to generate VTTR. The ISL88550A is suitable for DDR, DDR II, and DDR III memory power supplies; desktop computers, notebooks and desknotes; graphics cards; game consoles; and networking and RAID applications.

The ISL88550A buck controller drives two external N-channel MOSFETs to generate output voltages down to 0.7 V from a 2 V to 25 V input with output currents up to 15 A. The LDO can source up to 2.5 A and sink up to -2.0 A continuously. Both the low-dropout output and the 10 mA reference buffer output can be made to track the REFIN voltage via a built-in resistive divider. The PWM controller in the ISL88550A uses constant-on-time PWM architecture with a programmable switching frequency of up to 600 kHz. This control scheme handles wide input/output voltage ratios with ease and provides 100 nsec "instant-on" response to load transients while maintaining high efficiency and a relatively constant switching frequency.

The ISL88550A offers full programmable under-voltage protection/over-voltage protection and skip-mode options that are suitable in portable applications. The VTT and VTTR outputs track to VREFIN/2. The high bandwidth allows transient response without the need for bulk capacitors, thus reducing the cost and size. The ISL88550AIRZ and ISL88550AIRZ-T devices in lead-free packaging are both priced at $2.85 for quantities between 100 and 999 units.