Power Management Solutions
Mixed-signal Power Manager
Power management is a specific subset of features and requirements of total system management solutions, especially in high availability systems.
To create a reliable system you will naturally need to use complex devices, often mixing FPGAs, microprocessors, ASICs and ASSPs on the same board. Many of such devices require different power supplies to achieve their full functionality. Often these supplies must be applied in a predetermined and consistent order known as power sequencing. This power supply switching is often achieved by controlling point of load supplies (POLs) with some form of programmable device—a microcontroller or programmable logic device (PLD), for example. Proper sequencing will also limit any inrush current effects that can put strain on the system power supplies.
Two types of POLs exist: analog point of loads (APOLs) and digital point of loads (DPOLs). The two are very similar in that they both provide localized power to a given subsection of a board, can be enabled (switching on the power supply) and can monitor each supply. Figure 1 gives an example of both types of POLs. A DPOL is essentially an APOL with an I2C bus added. POLs can also be controlled to achieve any power-down sequencing requirements.
Figure 1: Examples of Point of Load Regulators
|Analog Point Of Load Regulator
||Digital Point Of Load Regulator
POLs allow voltage to be monitored via dedicated pins that become active if there is an issue with the output supply, letting the host system controller know there is an issue and correcting or compensating either locally or remotely. To ensure the correct operation of a system at extremes of voltage, the DPOL can be used to allow thorough testing of a circuit by setting the voltage using the PMBus in lab conditions.
Many systems, especially those that are deployed remotely, will incorporate some form of power monitoring circuitry to help in the determination of faults and other anomalous conditions. Most POL supplies have some form of "sense" output which indicates whether the supply is active or there is some other issue with the output. The output from a POL can often be trimmed using analog or digital techniques to optimize the supply rails for performance and/or power consumption.
Designing for power-up sequencing can be a complicated and time consuming task, especially if there are multiple devices with multiple rails that have to be sequenced correctly for correct operation. Having a dedicated software tool that enables the control of a power sequencing solution and can present a visualization of this helps designers quickly and efficiently achieve their desired power supply control.
Table 1 outlines the requirements for power controllers and how Microsemi's SmartFusion® customizable system-on-chip (cSoC) devices address these needs.