VI BRICK PRM+VTM Architectures and Applications

The PRM control system and supporting ASICs enable the VTM output voltage to be controlled using a choice of methods.

Local loop control is the simplest control scheme. Under local loop control, illustrated in Fig. 7, the PRM senses its own output voltage and regulates the Factorized Bus Voltage to a constant value. Load voltage will exhibit a "droop" proportional to the VTM output resistance.

Figure 7 - FPA with local loop control Click image for larger view

Under adaptive loop control, illustrated in Fig. 8, the VTM sends a signal back to the PRM to enable the PRM to adjust the Factorized Bus Voltage to compensate for the VTM output resistance. Adaptive loop control provides improved regulation over the simple local loop control — within +/- 1% — yet requires only a simple, non-isolated, feedback connection between the VTM and PRM.

Figure 8 - FPA with adaptive loop control Click image for larger view

Under remote loop control, illustrated in Fig. 9, the voltage at the load is sensed and fed back to the PRM. This feedback protocol provides the most accurate load regulation — within +/- 0.2% — but may require isolation in the feedback path.

Figure 9 - FPA with remote loop control Click image for larger view

With the addition of a (PI1004) Picor point-of-load IC, remote loop control can incorporate a digital control option compatible with the latest processor VID specifications.

Next >