The HP iPAQ 1945 illustrates the ongoing progress in shaving cost for color PDA devices. While much of the advance comes in the form of collapsing digital IC content, an intriguing mix of mixed-signal integration and still-prevalent discrete power management tell the rest of the story.
Introduced in June 2003, the HP iPAQ 1945 uses Microsoft's Pocket PC 2003 Pro operating system. The PDA design is centered around Samsung's 266 MHz S3C2410X02 ARM920T-core based RISC processor which also supports on-chip cache, memory management, expansion memory interface, and an LCD controller. Additionally, the Samsung part targets squarely at PDAs, and as such integrates several analog supporting roles. An internal 8- channel 10-bit A/D converter is used for voice note capture in the iPAQ and the resistive touch screen is interfaced directly to a built-in controller. An internal phase lock loop is also provided for assisting with system clock generation.
Not all analog content is cooked into the Samsung part however. To support a fairly rich audio capability, the iPAQ uses a Philips UDA 1380 combination stereo CODEC and headphone amplifier chip, with a National Semiconductor LM4890 audio power amplifier further boosting signal for the built-in speaker. Local area wireless for the iPAQ is handled with a Bluetooth module manufactured by Zeevo of Taiwan. Both digital baseband and transceiver radio circuitry are combined on a common IC"only a separate flash memory is paired with the Zeevo chip in the ceramic module.
Despite all this integration, the iPAQ continues the trend of discrete power management. A Semtech battery charger chip, TI DC/DC converter, and Maxim white LED driver are joined by an array of LDO regulators and their related passive components. On balance, a distributed, small-scale integration design addressed system unique power management needs for the iPAQ"simple, safe, and sometimes cheapest. Rapidly evolving handheld designs often demand the design flexibility made possible by taking the road less integrated.
So just how Analog is your Personal Digital Assistant? Of the roughly 600 electronic components used in the HP design, only a small fraction formed the binary heart of the system"testimony to the challenges of analog design and related opportunities in the component space. With design needs ranging from amplification to regulation to EMI control, it seems unlikely that small-scale analog devices will disappear any time soon.
David Carey is President of Portelligent. The Austin, Texas company produces teardown reports and related industry research on Wireless, Mobile, and Personal Electronics.