Abstract

In enterprise server applications, the latest Intel® VR14 specification introduces the requirement for accurate system input power monitoring. This allows tracking of average system input power, estimating the execution time of high power bursts, and signaling to reduce power when system input power exceeds a critical threshold. System input power can be directly monitored using an input-power signal or indirectly using system input current and system-input voltage as alternatives.

This application note demonstrates accurate and high-speed system input current monitoring using TPS25984, TPS25985, or TPS25990 eFuses to implement PSYS™ and PSYS_CRIT#™ in a VR14 multi-phase controller. This document begins with the definitions of PSYS™ and PSYS_CRIT#™, along with their accuracy and bandwidth requirements. Next, the implementation of the PSYS monitor is discussed. Then, the ISYS register and gain selection guidelines in conjunction with TPS25984, TPS25985, or TPS25990 eFuses are depicted, along with a design example. After that, the functional verification of PSYS™ and PSYS_CRIT#™ in the TPS536C9T VR14 controller are presented. Finally, the aggregation of the voltage outputs from multiple PSYS monitors connected to the same input power supply is illustrated in detail.