How "digital" is your Digital Still Camera?

The surge in popularity of digital still cameras (DSC) has been a bright spot for the beleaguered component industry, finally consuming meaningful quantities of semiconductor content. In many digital electronics hold the majority seat of DSC NAND flash, NOR flash, and SDRAM storage typically surround a mix of DSP-Core ASICs and microcontrollers. Nonetheless, digital cameras also owe their success to the quiet but critical support from a broad range of analog components.

Examining the recently-released Olympus C50, one sees strong analog content in three areas- image capture front end, optical control, and power management. Image capture remains a centerpiece of analog art. The C50 uses the 5-megapixel MN39593 CCD imager from Matsushita. Output from the CCD device is a serialized string of analog voltage levels corresponding to individual pixel values from the sensor. CCD output signals are quickly shuttled into an analog front-end CCD processor chip, the Analog Devices AD9846A, where correlated double sampling (to remove low-frequency noise) and programmable gain control (to adjust 'exposure') are dealt with prior to analog-to-digital conversion and subsequent digital picture processing. The Fujitsu MB3883 provides a six-channel DC-to-DC converter for producing the myriad of supply voltages needed by the CCD and associated circuitry.

In addition to the CCD voltage supply, a total of nine smaller voltage regulators are sprinkled throughout the C50 camera to manage local supplies for system devices. In the optics arena, motor controllers for zoom optics combined with sophisticated motor control loops for the focus optics are implemented in a Mitsubishi #M50232 motor controller IC. Additional important analog functions in the C50 include high-voltage controlled discharge for the flash strobe lamp, and conversion of digital images to high-quality analog video for external viewing on a TV.

In the end image capture and display are intrinsically analog functions-the human eye responds to brightness, color, clarity, saturation, and dynamic range, not megahertz and megabytes. While the DSC is indeed a largely digital product, it is analog content that ultimately provides the critical pieces to bring it all together and deliver film-quality images.

David Carey is President of Portelligent (www. teardown.com). The Austin, Texas company produces teardown reports and related industry research on Wireless, Mobile, and Personal Electronics.