Microcontrollers continue to shrink in size and cost. For example, Microchip's latest six-and eight-pin PIC10Fs have a footprint of only 2 by 3 mm, which is 30% less than a SOT-23 package (Fig. 1). Many discretes are larger than these devices.
Because of an on-chip oscillator, these microcontrollers can utilize all of the pins except for the power and ground pins for peripherals. This is critical when the number of I/O pins is half a dozen or fewer.
The PIC10F family sports an 8-bit PIC core with up to 1k instructions and 41 bytes of RAM driven by an 8-MHz internal oscillator (Fig. 2). These microcontrollers also have an 8-bit timer and a watchdog timer. The 8-bit analog-to-digital converter (ADC) and comparators are optional. The sleep mode uses only 100 nA, and the chip will run on 2 to 5.5 V. The pins can sink up to 25 mA.
These tiny controllers can still do a lot, even with a limited complement of pins. They can handle traditional chores like flashing LEDs. They also can be used to implement a digital combination lock using a variety of input devices such as keypads decoded digitally or via the 8-bit ADC.
Programming these little chips for dedicated functions can change the way designers create products. Multiple, identically programmed chips can simplify system expansion as well as reduce the complexity of the system (see "EiED Online: Building A Six-Pin PIC Network" at www.electronicdesign.com, ED Online 9804). They also can be an interesting complement to single-chip ZigBee systems, providing intelligent sensor information to the wireless transport system.
Microchip isn't alone in delivering compact platforms. Other microcontroller vendors have tiny offerings as well. Silicon Labs' C8051F300 family packs an 8051 into an 11-pin, 3- by 3-mm quad flat no-lead (QFN) package that sports a comparator and an eight-channel, 8-bit ADC plus 8 kbytes of flash and 256 bytes of RAM. These devices even offer a UART and SMBus support. Pricing for the C8051F300 starts at $2.15, while Microchip's PIC10F costs $0.44. Still, you could hide either chip in the space needed for a surface-mount LED and resistor. All you need is power, and not much of that.
So what kind of dedicated devices are you building with these tiny chips? Drop me an e-mail and let me know.