Analysis of the advantages of digital power management

These environments require power management functionality to be integrated into the building blocks.

And constitute a complete working and sound power system. Power management includes: power system monitoring. Sequencing and tracking monitoring and failure protection. In fact, each function is isolated from the high current circuit of DC-DC conversion.

In a typical 48V power system using an intermediate bus (IB) and power management, a single brick converter generates the intermediate bus voltage. This voltage feeds a number of POL converters that provide each low voltage output rail. The brick converter also maintains isolation from the 48V input circuit (see Figure 1).

Potentia Semiconductor's PS-1006 power management device can be used on the 48V primary side to handle input start-up limit, start-up and shutdown control . Another power management device, the PS2406, is used on the secondary side to control start - up sequencing and output voltage regulation and provide failure protection for overvoltage and undervoltage conditions.

This dedicated digital power management device is far superior to the commonly used analog methods or general-purpose microcontroller or PLD methods.

The PS24O6 can control all output rail voltages in real time. Its internal logic can protect startup and shutdown. Follow the required timing sequencing under all conditions without relying on the power converter startup time or time delay circuit. Internally lock the startup threshold. Prevent enabling a rail until the previous rail has started correctly. Failure management logic ensures that the remaining rails are still shut down in time after a failure occurs.

Digital Fault Detection Overvoltage and undervoltage fault detection is usually based on multiple voltage sampling. Use ADC and digital averaging to identify fault conditions and instantaneous voltage transients. This can improve system performance by shutting down quickly in a fault condition and avoiding incorrect shutdown. The ADC is selected for fast sampling so that it can react to faults faster than a general purpose microcontroller. Fault detection voltage thresholds and timing are configurable to suit the application.

The DC-DC converter regulation input is driven by a dedicated DAC within the PS-2406 under the control of the device's I2C interface. This technique allows precise adjustment of settings and can be driven by system software. This makes it easy to implement software-based features such as long-term output voltage stability and automatic margin control.

All voltage thresholds are based on an internal reference and have an overall accuracy better than 0.5% while time delays and digital filters derive timing values ​​from the device clock. The timing values ​​can be particularly accurate especially if the clock is controlled by a crystal or ceramic resonator.

The PS-2406's I2C interface allows the board controller to read all output voltages in real time. This enables comprehensive power system monitoring. Current shunts can be added if necessary. Output current measurements can be made via the I2C interface.

When the PS-1006 is used for primary management (Figure 1), the primary status can also be controlled through the secondary I2C interface. The PS-1006 can measure primary parameters and report status to the PS-2406 through the isolated PI-Link interface. These parameters include input voltage, output current, fuse status, input overvoltage and power saving.

Once the design is approved, the same configuration files are used for all units during board assembly and test. Performance is consistent between units and does not vary, unlike in analog designs where component tolerances can cause variation.

Startup Sequence In any complex on-board power system, a significant portion of the total design effort requires defining and implementing power management functions. This is the functionality required for control and monitoring of power converters. Power management functions include startup and shutdown sequencing and tracking, real-time voltage and current measurement and readout, fault protection and output voltage regulation control. Many applications require isolation between the primary and secondary portions of the power system, which complicates the design when remote readout of system voltage and current is required. In addition, when developing related products, especially when the power system is embedded on the circuit board, its requirements are bound to change significantly.

Traditional power system design relies on discrete analog circuits to implement power management functions, and relies on amplifiers, comparators, and RC time delays to set parameters. As the design progresses, any changes require component changes, and often require reprocessing of printed circuit boards. The use of dedicated digital power management devices allows operating parameters to be set through configuration software rather than circuit components. With this method, parameters can be easily changed as needed during the design process without making hardware changes.

Configuration Software All PS-2406 functions are configured using the associated Power Center Designer software. The initial configuration of the power converter (power topology) and the required startup sequence are entered graphically via on-screen graphics and check boxes.

Once the power topology is entered, the operating parameters (such as voltage levels, time delays, voltage adjustment settings, and GPIO pin functions) are configured on the parameter input screen. Overvoltage and detection time parameters for each rail can be set separately. Overvoltage detection is also suitable for intermediate bus voltage detection. To further simplify the design process. All parameters are automatically set to typical default values ​​in the PowerCenter Designer software, and designers only need to fine-tune a few values ​​to suit the application.

When all parameters are entered as required, they are downloaded to the PS-2406 using the programming cable via I2C terminal 13. If any parameters need to be adjusted during development, they can be edited and reloaded in just a few minutes without removing possible devices from the board.

If a general-purpose microcontroller is used for power management, custom software must be developed for each application, and implementation modifications are complex. Extensive testing is required to confirm the correct logical performance of the software under all functional and failure conditions.

Using a device designed specifically for power management applications, its internal logic is predetermined, and only the configuration can be changed to suit different applications. Changing the configuration only takes a few minutes and does not require the development and testing of any custom software.

Dedicated digital power management controllers can greatly improve end-product performance, allowing power system monitoring to be fully integrated into product management software.