Configurable applications processor tackles multiple mobile environments
This "Product How-To" article focuses how to use a certain product in an embedded system and is written by a company representative.
Today's technologies and ever-greater consumer expectation levels result in high-end mobile handsets that contain an arsenal of computing power. To minimize development risk, time-to-market demands, and cost pressures, handset designers are driven to employ proven platforms for the major elements of their designs.
As a result, semiconductor vendors offer application processor platforms that include ICs, software stacks, reference designs, and design tools to produce complete but proprietary ecosystems. These different environments require intelligent power management for as many as thirty or more individual power domains, posing product designers a complex set of requirements that ideally require a uniform solution.
Space and complexity constraints render discrete power-management devices obsolete for today's high-end mobiles. In their place, dedicated power-management ICs — or PMICs — are available that use a system-level approach to supporting the various mobile environments. Besides the obvious advantages of saving board space, reducing the bill-of-materials and manufacturing costs, such devices may also integrate other circuit functions that simplify the design. Examples include audio CODECs, backlight LED drivers, and interfaces for memory cards and touchscreens.
In addition, PMICs often include a multimode battery charger that autonomously provides charger detection, charge control, and safety supervision for the battery pack. The result is a PMIC that significantly improves space efficiency and battery life, but that really only suits a particular vendor's mobile environment. For instance, Dialog Semiconductor's DA9035 specifically targets Marvell's W-CDMA platforms.
Flexibility adds value
While target-specific PMICs achieve vast performance improvements over their discrete-component predecessors, product designers would ideally prefer a single PMIC that they can tailor to suit a multitude of applications—and without incurring any significant compromises that would make this more flexible approach unattractive.
In this way, designers could re-use the same underlying PMIC architecture in a number of products, amortizing development costs and extending product lifetimes. Moreover, if the mobile platform is available in a variety of versions with different peripherals that suit various applications, being able to reconfigure the PMIC may enable the same basic design to reach a greater customer base at the lowest possible incremental development cost.
By means of example this video illustrates this by adding a camera module to an existing design. Click on picture to view.
Because each mobile platform defines resources such as the host processor, RF system, peripherals, hardware accelerators, multimedia coprocessors, and memory—all of which require power management support—designing a suitably flexible PMIC is quite a challenge. Most often, the power supplies for the processor core come from the dc/dc converters within the PMIC, and its low drop-out regulators (LDOs) then deliver clean and tightly-regulated system supplies.
As a result, every major platform change invokes the need for a change in power requirements—typically requiring new power supplies and a method to control power sequencing, ideally without adding overhead to the host processor.
Clearly, any configurable PMIC must offer sufficient hardware resources to maximise its applications potential but without making the silicon prohibitively expensive. The device must also be easy for product designers to apply, which implies the need for software and a programming interface that's easy to use and affordable. Ideally, it should also be possible to apply the PMIC to a given mobile reference platform without requiring any change of system software.
It's also highly desirable for the PMIC to be able to adapt to the multiple operating modes that high-end mobiles employ, at the same time ensuring robust power-up and power-down sequencing for the processor, co-processors, and peripherals. Ideally, the PMIC should detect and initiate power/wake-up and then relinquish power-management control to the host processor as the handset transitions between its operating modes.
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