Integrated Digital POL Power-Management System Simplifies Design, Cuts Costs

Power systems are becoming more complex. To satisfy different circuit power-supply voltage and current needs, more and more point-of-load (POL) regulators and dc-dc converters are crowding pc boards—to the point where they're becoming unmanageable. The problem is threefold: the amount of pc-board space being absorbed, the number of external components required, and the lack of coordination between the horde of POL converters.

By investing considerable resources to develop a digital silicon-based architecture, its Z-One architecture, Power One came up with a unique system that fully integrates a power system's management functions with those of the power-conversion circuitry. What results is a solution that cuts overall system-level costs by some 20% to 50% compared to existing approaches and allows an industry-record 32 POL converters to fully communicate with each other under the command of a single system controller (Fig. 1).

According to Power One, this is the most capable power-management system by far. The nearest competitor, it claims, offers only 12 POL converters with limited functionality and the need for external tracking field-effect transistors (FETs).

Central to Power One's Z-One system shown in Figure 1 is the company's single-wire Z-One digital bus. The high-speed bidirectional bus provides both frequency synchronization and data transfer and can access all POL converters in a single communication cycle. It carries all the information to and from the POL converters and the Power Digital Manager (PDM), including all parameters for each POL converter, such as the output voltage, sequencing, tracking, monitoring, interleaving, protection thresholds, feedback loop configuration, and fault-management information. The digital POL converters can operate with a wide input voltage range from 3 to 13 V.

The Z-One system integrates two ASICs, the ZM7100 PDM, and the maXyz ZY7000 series of POL converters. Both are based on Power One's custom silicon.

The ZM7100 PDM is a centralized system manager that programs and controls sequencing, tracking, supply supervision, and intelligence for the analog-to-digital converters (ADCs) with margining, reset, and environmental-monitoring capabilities (Fig. 2). The Z-series non-isolated POL converters receive commands from the ZM7100 PDM that change the settings but also communicate their status back to the controller. Everything can be controlled by Power One's Z-series Intelligent Operating System (ZIOS), which features a graphical-user interface (GUI). Engineers can easily configure and simulate power architectures during system design. To add more flexibility and control to the system, users can program the ZM7100 controller through an industry-standard I²C interface.

The ZM7100 can program and manage up to 32 POL converters. It continuously monitors their output voltages, currents, and temperatures. In addition, it monitors the intermediate bus voltage, accepts external programmable interrupts, initiates crowbar protection, and controls dc-dc front ends, including those not manufactured by Power One.

In developing this new power-management system, Power One created several key pieces of intellectual property. A significant number of patents related to the implementation of the overall system's architecture, including control and configuration, as well as patents in the design and implementation of the digital pulse-width-modulated (PWM) controller have been filed.

The first POL converter to be available is the 20-A ZY7120 with an input between 3 and 13 V dc and a programmable output of 0.5 to 5.5 V dc within a tolerance of 1%. The 5-A ZY7105 and the 10-A ZY7110 POL converters and ZX7000 series power blocks are planned series expansions.

Each POL converter features current sharing and active control of the low-side FET for turn-on with 100% pre-biased outputs. The 20-A converters come in surface-mount packages for either vertical or horizontal mounting, with respective dimensions of 1.25 by 0.3 by 0.55 in. and 1.25 by 0.63 by 0.3 in. (Fig. 3).

The converters use digital PWM control. The 20-A products can handle current densities of up to 52 A/in.² They can also be used as standalone components without the ZM7100 controller, via default tracking, sequencing, and protection settings, as well as resistor output-voltage programming, or a standard VID code.

GUI PROVIDES FLEXIBILITY Power One's ZIOS GUI, along with its GUI development tool, provides a comprehensive set of management and design capabilities for a power-management system, including output tracking and sequencing, POL-converter frequency synchronization and interleaving, and the setting of thresholds for overvoltage, undervoltage, and overcurrent protections. Four independent OK signal lines are available for comprehensive fault management.

Various system configuration windows can be set up for programming and viewing a host of power-system activities. For example, ZY7000 POL converters can be set up in groups to accelerate the programming process (Fig. 4).

Pricing for the ZM7100 DPM controller is $12 to $15, and the 20-A POL converter is expected to cost $16 to $20, in prototype quantities. Availability is expected in the third quarter.

Power One Corp.www.power-one.com (803) 987-8741