With industry's call for the highest possible system efficiencies taking center stage, today's DC/DC conversion ICs for advanced telecom, datacom, telecom, and portable products are taking on more power-management duties.
Ever power-hungry systems aside, it's a difficult assignment complicated by endless cost considerations, much the result of more complex microprocessor-based system requirements and the sheer volume of today's portable and wireless applications. That leaves chip makers with a few ways to go: More advanced designs that embrace the system-on-a-chip idea, chips that focus on higher efficiency through digital power conversion, and sophisticated development systems that enable the designer to grasp and maintain an effective design process for faster time-to-market.
A sampling of the more notable devices shows some very condensed power-with-power management chips, including the AS3653 from austriamicrosystems (Raleigh, NC), which has perhaps produced the most highly integrated chips to date. The IC, which includes general purpose audio circuitry for portables, and thus approaches the system-on-a-chip, touts complete support for the entry-level GSM and CDMA market. It includes 10 LDOs, a chemistry-independent battery charger, backup charger, gas gauge, real time clock, microphone biasing circuitry, support for LED lighting, and eight general-purpose I/O lines.
Texas Instruments (Dallas) says its TPS65023 is the first power management IC fully optimized to support multimedia systems that employ DaVinci processors, i.e., a DSP-based system solution for developing tailored digital video applications. It includes three step-down converters (1.5, 1.2, 1 amp) and two general-purpose 200-mA LDOs. Suited for portable media players, digital still cameras and the like, the device provides dynamic voltage scaling and an efficiency of up to 95 percent.
STMicroelectronics' (Lexington, Mass.) STw4810 is for application processor engines (APEs), such as ST's STN881x Nomadik processors. It's a USB on-the-go transceiver that includes two DC/DC step-down regulators (up to 600 mA at 1.5 volts for the core supply and 600 mA at 1.8 volts for I/O functions) and three LDOs for auxiliary devices and peripherals. It includes processor supply monitoring and reset functions and two I2C interfaces.
Other systems include the LP5552 energy management unit and APC2 advanced power controller from National Semiconductor (Santa Clara, Calif.) to provide extended functionality to prolong battery life. The combination can reduce power consumption in existing high data-rate processors by 70 percent. The LP5552 includes two adaptive 600-mA, 0.6-1.2 volt buck regulators that enable the processor to scale its supply voltage to the minimum level required. Five programmable regulators power the various I/O, oscillator, and PLL circuitry and embedded and external memories. Communicating with the LP5552 via the system's PowerWise (PWI 2.0) interface, the APC2 is a macrocell that includes a hardware performance monitor to support adaptive voltage and frequency scaling. It automatically calibrates for process and temperature variations.
Primarion's (Torrance, Calif.) dual-phase PX7520, part of the company's Di-POL family, sets claim to the industry's first dual-phase programmable digital-power conversion and power management IC. The stand alone device, a digital point-of-load controller, incorporates two PWM outputs for high-current buck converter topologies. Up to four such controllers can be synchronized for multiphase operation. Its I2C PMBus serial interface coordinates control and monitoring.
With the digital power conversion plus management idea taking hold, digital signal controller (DSC, versus DSP) solutions are also coming into use. More specifically, there's a growing grey line between where power conversion ends and power management begins. A sampling of some of the more interesting devices for the more basic systems include TI's TMS320F28044 DSC, which manages up to 16 DC/DC converters. Similarly, Freescale's (Austin, Texas) 56F8000 DSC is suited to motor control as well as digital power conversion. Another DSC chip from Microchip (Chandler, Ariz.) uses the company's highly integrated dsPIC devices. In addition, Zilker Labs (Austin, Tex.) ZL2105, a state machine, claims the most power-with-power management facility for 3-amp designs. Power-One's (Camarillo, Calif.) ZM7300, also a "digital power" device, has a good measure of power management (click here for a summary on digital power chips such as offered by Freescale, Microchip, Power-One, and Zilker).
With microprocessors in the fray, system complexity is a bear fast getting out of control. To help keep a cap on the power management issue, TI's DSP Starter Kit , a hardware/software development product, allows designers to plan, optimize and accurately gauge real-time power consumption for the company's TMS320C55x DSP designs. The development kit includes USB-based measurement hardware from National Instruments for power monitoring.
With the wireless and portable arena still growing, Lattice Semiconductor (Hillsboro, Ore.) specifically addresses the cost of dedicated power management with its ispPAC-POWR607, a second-generation device in the company's Power Manager II family that's priced at less than $1 each in high volumes. The device, which supports 16- and 32-bit microprocessor-based systems, uses an on-chip macrocell CPLD and four programmable timers to monitor up to six circuit-board power supplies and generate the appropriate CPU reset and power supply fault-interrupt signals. Earlier, their macrocell-based supervisors in the ispPAC-POWR1014/1014A family, which provides monitoring of multiple supplies, sequencing and tracking, trimming and margining, voltage measurementl and status monitoring through a PC interface, are designed to provide a smaller footprint and more features at a lower cost, in this case about $1.95 each in 10k quantities. The ispPAC-POWR1014 is suited to monitoring applications in consumer, telecom, and automotive applications, and plasma display TVs. The ispPAC-POWR1014A addresses midrange applications that require power supply voltage measurement, including mezzanine cards, base station line cards, and servers.
Among the more populated ICs for portables, Summit Microelectronics' (San Jose, Calif.) SMB118, part of a second generation of multi-output programmable power manager ICs, integrates six precision programmable regulators and a programmable battery charger. It incorporates three synchronous step-down regulators, one step-up regulator, one configurable step-up or step-down regulator, and one LDO. It also includes a battery charger. Designers program the chip via a GUI.
In addition, the SC905 from Semtech (Camarillo, Calif.) features nine ultralow dropout (ULDO) regulators that source from 80 to 300 mA for cell phone applications. Five of the devices power analog functions (audio, RF), three power digital circuitry, and one can be used as a general supply or as a vibrator motor supply that delivers up to 150 mA.