Smart Power Stages Increase Accuracy While Simplifying Designs

06 December 2016

Vishay Siliconix?SiC645 and SiC645A smart power stages. Source: Vishay. Vishay Siliconix?SiC645 and SiC645A smart power stages. Source: Vishay. Meeting the need for real-time processor and memory power consumption monitoring in high-performance telecom equipment and datacenter servers, Vishay Intertechnology, Inc. has introduced two 60 A VRPower® smart power stages with integrated current and temperature monitors for multiphase DC/DC systems. Combining power MOSFETs, an advanced driver IC, and a bootstrap FET in the thermally enhanced, low-profile 5 mm × 5 mm × 0.66 mm PowerPAK® MLP55-32L/QFN package, the Vishay Siliconix SiC645 and SiC645A simplify designs and deliver higher accuracy than comparable standard DrMOS products, while offering a 16% smaller footprint than similar competing devices.

Unlike solutions that monitor power consumption using inductor DCR sensing—a technique with lower accuracy that requires external components such as a thermistor for temperature compensation—the SiC645 and SiC645A use low-side MOSFET RDS(ON) sensing to accurately report current (IMON) and temperature (TMON) using 5 mV/A and 8 mV/C signals, respectively. This method of current sensing is accurate over a wide load range, and is internally temperature-compensated, simplifying designs by removing the need for external circuitry. In addition, it eliminates current sense traces while delivering fast performance without noise or external filtering.

The power stages’ improved accuracy meets Intel’s stringent VR13 and VR13.x current-monitoring accuracy requirements, and allows for better utilization of a server CPU’s turbo boost capability—a critical advantage for datacenter customers requiring improved performance without increasing costs. Light-load efficiency is supported by a dedicated low-side FET control pin.

The devices offer an input range of 4.5 V to 18 V, and are optimized for high-frequency and high-efficiency VRMs and VRDs to power microprocessors and memory for servers, networking and cloud computing; GPUs in high-performance graphic cards and video game consoles; as well as general purpose multiphase point-of-load (POL) DC/DC converters. The package of the SiC645 and SiC645A can be cooled on both sides, while low package parasitic resistance and inductance enable high switching frequencies of up to 2 MHz.

Fault protection features for the RoHS-compliant, halogen-free devices include high-side FET short and over-current protection, over-temperature protection, and under-voltage lockout (UVLO). The power stages feature open-drain fault reporting output. The SiC645 and SiC645A support 5 V and 3.3 V PWM tri-level input, respectively, and are compatible with Intersil’s ISL68/69xx and ISL958xx digital multiphase controllers.

Samples and production quantities of the smart power stages are available now, with a lead time of 10 weeks.

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