Signal-Chain-on-Chip Could Cut Cost and Power Draw of Handheld Instruments

SAN FRANCISCO – A new low-power microcontroller from Texas Instruments (TI) draws so little current that the company’s engineers are demonstrating it by using grapes to power it.

The MSP430F32x0 microcontroller--aimed at high-precision, low-cost measurement applications--is being described as the first-ever “signal-chain-on-a-chip” microcontroller because of its all-inclusive integration of analog components for such applications. The new device, which draws a real-time clock standby current of just 1.1 ìA, is said to be ideal for handheld devices such as altimeters, weight scales, multi-meters, and scuba diving pressure meters.

“The concept is to have one chip that will meet all the needs of customers who are interested in low-cost, high-precision measurement,” notes Juan Alvarez, marketing manager for MSP430 microcontrollers for TI.

In addition to its exceptionally low current draw, the new device’s claim to fame is its integration of the microcontroller, 16-bit analog-to-digital converter, programmable gain amplifier, 12-bit digital-to-analog converter, supply voltage supervisor, flash memory, LCD driver, and charge pump. In a sample altimeter application, TI engineers showed how the new microcontroller could cut end device unit costs from $7.95 to $2.95, simply by replacing discrete analog components with the single-chip solution.

The device’s low current draw, however, may be its premier feature. In addition to its 1.1 ìA draw in clock standby mode, it also uses just 250 ìA in its active mode. TI engineers demonstrate the MSP430’s low-power operation at trade shows by using grapes, zinc, and copper to make a makeshift battery of sorts.

“We connect the grapes in series and we’re able to do real-time clock operation,” Alvarez says. A TI speokesman says that the company has run a real-time clock consecutively for more than a day on grape power.

For handheld applications where space is at a premium, TI engineers say that the new microcontroller also serves as a means for reducing printed circuit board real estate. A sample handheld altimeter demonstrated for Design News incorporated a circuit board measuring less than 2 x 2 inches, about half the size of a conventional counterpart. The company claims it could easily reduce that circuit board to the diameter of a quarter, if required. TI engineers say that the device’s optimized peripherals are also ideal for creating a smaller, more accurate blood cholesterol meter for the medical industry.