ISL8273M - 80A Single Channel Digital PMBus™ Step-Down Power Module
Welcome to the product training presentation of the ISL8273M. The ISL8273M is the latest addition in Intersil’s family of fully encapsulated power management modules. This presentation will give you a brief overview of the device’s feature set and performances.
A Fully Integrated DC to DC Point-of-Load Solution
By integrating the switching controller, FET drivers, FET transistors, inductor and most passive components, a power module provides the simplest and fastest time to market architecture to implement a versatile and performing point of load. Intersil’s power modules only require a few external components to operate; they are easy to use and configure for a variety of operating points and conditions and offer some of the highest power densities on the market.
The ISL8273M is a complete DC to DC step-down power supply solution encapsulated in a single package. Operating from the industry standard 5V or 12V power rails, it is capable of providing up to 80A of continuous output current, can be programmed to output voltages as low as 0.6V and offers better than 90% efficiency on most conversion ratios. Its unique ChargeMode control loop architecture requires no external compensation, can operate up to 1MHz and allows the ISL8273M to react to any output current load step within one single clock cycle.
The ISL8273M implements a standard PMBus compliant interface providing not only a complete real time customization of all operating parameters but also advanced telemetry capabilities for system health report and monitoring. In addition to its digital interface, this device offers a pin-strap mode allowing most common operating parameters to be set through external resistors, virtually eliminating the need for any PMBus commands or programming to operate. For complex configurations, the ISL8273M incorporates on board non-volatile memory that can be programmed to the desired configuration and settings.
The ISL8273M is not only a standalone device, up to four modules can be paralleled to provide up to 320A in a single power rail thanks to the ISL8273M active current sharing mode. In this configuration, multi-phase or phase spreading operations are supported. Lastly, an array of built-in advanced protections ensure safe operations under abnormal operating conditions.
The ISL8273M incorporates, in a small 18mm x 23mm footprint thermally enhanced HDA package, all the main power components such as the controller, power FETs and inductors. It only requires a few external components to operate making it a solution of choice for an easy design in without sacrificing performance or reliability, and is ideally suited to power the latest generations of ASICs, DSPs, FPGAs, and memory.
Typical Standalone Application
The typical application diagram shown here is a good illustration of how easy the ISL8273M is to design in. Only a few external components are required to operate; input and output capacitors along with a few decoupling capacitors and resistors are the only required components to be chosen. A set of optional external pin-strap resistors allows users to easily configure the device for standard operations when typical values are required for a subset of operating parameters such as output voltage and switching frequency amongst others. In this mode, no programming or communication through the PMBus is required and usage can be made of the dedicated control pins which provide a direct mean to enable the device, perform some margining testing and monitor power good status. The ISL8273M datasheet provides precise guidance to select these components based on the exact operating mode and performance expected.
Additionally, Intersil’s PowerNavigator™, a design and configuration software, fully supports the ISL8273M providing the power designer with an intuitive and easy to use interface, reducing the development time for the overall power train solution.
The Intersil proprietary ChargeMode control loop architecture combined with high performance on board FETs allows the ISL8273M to operate at better than 90% efficiency on most voltage conversion ratios. The efficiencies can even reach about 93% on a typical 12V to 2.5V conversion for currents above 25A. This is a critical performance that reduces the thermal stress on the device and facilitates thermal management of the overall system. In addition, the ISL8273M can be configured to operate at up to 1MHz with its internal clock providing extreme flexibility when optimizing efficiency and transient response performances.
The ISL8273M control loop architecture not only provides flexibility in selecting the operating switching frequency, it also provides for an extremely fast control loop response to any output current load steps. The absence of any compensation components reduces the feedback loop response to a minimum and the ISL8273M is capable of reacting to an output load step within one single clock cycle. Additionally, digital knobs, the ASCR gain and residual, addressable through the PMBus or through an external pin-strap resistor, allow for fine customization of the control loop performance and therefore of the transient response.
This is a key benefit for the power designer. The ISL8273M does not require additional output capacitance to reduce the output voltage variations following a load step. Hence, the external capacitors footprint is kept to a minimum.
Thermal management is one of the greatest challenges in high power module design. Ultimate power rating, especially at high ambient temperature, is dictated by the module’s electrical and mechanical design. Using thermally efficient packages that can move the heat out of the module enables to deliver better thermal performance.
The ISL8273M is built upon Intersil’s patented single-layer conductive substrate in a high density lead frame array package (a.k.a. HDA). This technology provides excellent thermal conductivity to dissipate heat because of the single conductive layer of material. When combined with excellent efficiency, effectively reducing the amount of power dissipated inside the device, it allows the ISL8273M to supply close to 50A of continuous output current at 85°C of ambient temperature without any air flow on a 12V to 1V conversion.
Start/Stop and Sequencing
In addition to an outstanding electrical and thermal performance, the ISL8273M also offers a range of advance power management features. With high current/high power point of loads, it is often critical to precisely control how the power is delivered to the load as well as ensuring that various power rails, core voltage, memory or I/O voltages for instance, power up in a controlled and predictable order.
The ISL8273M provides fully programmable delay and ramp times that can be independently set to control not only the output voltage soft-start but also the soft-stop. Furthermore, when multiple power rails are present, the ISL8273M implements a complete programmable support for complex sequencing between the various power rails, through the single wire DDC bus, to precisely control the order at which the power rails are enabled as well as how they are disabled.
Multi-phase operations, also known as phase spreading or phase interleaving, is desirable when several converters share the same input power rail or are paralleled for higher output current capabilities. This technique, effectively forcing each channel to switch at a different time within the switching period, reduces both the output voltage ripple and total amount of input and output capacitance required for a given design.
As a standalone 80A capable device, the ISL8273M already operates in a 180° dual phase mode. When implemented along with other converters, up to 16 operational phase offsets can be selected as long as all converters are synchronized to the same clock.
Active Current Sharing
Powering up the latest generation of ASICs, FPGAs and memories often requires an output current capability above what a single converter or power module can achieve. Paralleling several power modules, thus summing up their maximum respective output currents, achieves the desired higher output current rail. In this configuration, in addition to the multi-phase operations described earlier on, it is important to balance as equally as possible the current each converter provides to the common output power rail and therefore reduce the input and output filter stress and equally spread the thermal dissipation between modules.
Up to four ISL8273M can be paralleled to achieve an output current of up to 320A. In this configuration, all modules, synchronized to the same clock, automatically adjust the phase offset for all channels achieving an automatic multi-phase conversion. They also implement an active current sharing mode through a master/slave configuration that effectively allows the master or reference module to broadcast and set the reference operating output current to all the slave modules through a single wire inter module communication interface, the DDC bus. Slave or member modules then adjust a digitally controlled output droop resistance to increase or decrease their respective output current to align with the reference output current achieving a perfect current and thermal balancing between modules.
Advance Power Management - Protection and Faults Management
With high output power capability often powering very expensive ASICs and FPGAs, it is critical to protect the load as efficiently and reliably as possible. The ISL8273M provides a built-in advanced protection scheme that ensures safe operations under abnormal operating conditions. Several operating parameters such as output current, input/output voltages and temperature are constantly monitored through four independent levels, two warning and two fault levels. Specific behavior to each individual fault can be configured from immediate shutdown to restart attempts. Furthermore, ISL8273M can broadcast its fault status forcing other modules or converters sharing the same DDC bus, to immediately shutdown based on their own configuration. This allows the fastest fault response and maximum load protection, as it does not require any system commands. In addition, upon detection of a fault condition, the ISL8273M takes a snapshot of its operating parameters and stores it in its non-volatile memory for later review; providing exact data on what caused the fault to occur.
Modern electronic equipment and systems are not only required to operate reliably but also required to monitor the system health and power consumption as well as being able to adjust parameters in real time to optimize performance. The ISL8273M, through an industry standard PMBus serial interface, enables the system to measure and monitor several operating parameters. It also allows the user to adjust any of the conversion parameters in real time, effectively optimizing the system for various conditions.
Power Up and Operational Modes
Several power up configuration and control modes are available with the ISL8273M. All options can be used exclusively or in conjunction with one another.
The ISL8273M comes preprogrammed with an internal default configuration bank which sets all default values for the operational parameters. Combined with the external resistor pin-strap option which sets basic operational settings such as output voltage, switching frequency, current sharing mode and soft-start amongst others, this mode allows the user to enable the device through its hardware control pins, without requiring any programming or access to the PMBus and often speeds up the powering up of the system during the development phases.
This same default internal configuration bank can be complemented by a user configuration bank, addressable through the PMBus or loaded through a commercially available programmer, to selectively customize all parameters and settings of the ISL8273M for advanced and complex configurations.
Lastly, during operations, any operational configuration and settings can be modified through a PMBus command for real time device and performance optimization, and potentially saved and stored in the user bank for it to be immediately active after the next power up.
While the ISL8273M does not require any programming to operate, the full extent of its features, versatility and performance is reached when taking advantage of both its internal non-volatile memory and PMBus digital interface. The ISL8273M, as Intersil’s most advance power module, supports in system programming as well as commercially available memory programmers. Intersil provides free software tools, PowerNavigator and the Production Configuration Tool (a.k.a. PCT), to develop, generate, load, and verify configuration files for its advance power modules family.
Design Tools - PowerNavigator
All Intersil’s advance power modules, including the ISL8273M, and more generally all Intersil digital power devices are supported through the PowerNavigator software. This software tool, available for free on Intersil’s website, provides a full dashboard and development environment for all the advance power architecture and solutions. It allows real time customization, monitoring, optimization, and creation of configuration files.
Full documentation, samples and evaluation boards are available to download or order online. Visit the ISL8273M product page for the latest information on the device and access to all online tools and resources.
Power Modules – Advance Power Line Up
Intersil’s family of power management modules span from performance analog to advance power solutions supporting multiple input power rails, output currents and a variety of basic and advanced power management features. The ISL8273M complements an already existing and comprehensive portfolio of advance power modules which shares most of the features reviewed during this presentation. This family also provides pin-to-pin compatibility to further facilitate the design reuse and migration between various levels of output current and point of loads. The ISL8273M is pin-to-pin compatible with the 50A ISL8272M device offering an easy upgrade to an 80A capable point of load.
Power Module Benefits
Intersil’s power management modules provide the simplest and fastest time to market architecture to implement a versatile and performing point of load. Its patented encapsulation and packaging technology allows the most compact form factor and reaches some of the highest power density on the market. This unique technology also brings significant improvements and benefits in reliability and manufacturing over a traditional approach with discrete power components.
Thank you attending this brief presentation on the ISL8273M. For further information and access to the latest documentation on this device as well as the latest news and information on all Intersil’s products, please visit our website at www.intersil.com.