Microchip has developed a single-I/O bus UNI/O EEPROM devices in miniature, wafer-level chip-scale and TO-92 packages, in addition to the 3-pin SOT-23 package.
Measuring 0.85 mm x 1.38 mm, the wafer-level chip-scale package (WLCSP) is approximately the size of a die and supports a manufacturing flow using standard pick-and-place machines. The long-leaded, 3-pin, TO-92 package is commonly used when the manufacturing flow is a hand-assembly process, or when it is mounted directly on cable assemblies.
The current market trend is to offer consumer products with more features than previous models, but smaller in size and lower in cost. This can be accomplished with higher levels of integration, the selection of smaller components with fewer pins or the utilisation of smaller packages. Because the UNI/O devices only need a single I/O port to communicate with the microcontroller, selecting components in a chip-scale package is the next step to take in further reducing the overall product size. Even though small size is a factor in any design, the lower overall manufacturing costs from a hand-assembly process can also drive package selection. This is where the through-hole TO-92 package can be utilised.