Maxim Integrated Products introduced the MAX127/MAX128 12-bit data-acquisition systems. These devices operate on a single 5V supply and accept analog inputs above the power-supply rail and below ground. Each device has eight analog input channels that are independently software programmable for a variety of ranges: +/-10V, +/-5V, 0 to 10V, or 0 to 5V for the MAX127; and +/-Vref, +/-Vref/2, 0 to Vref, or 0 to Vref/2 for the MAX128.

Range switching increases the effective dynamic range to 14 bits and provides the flexibility to interface a 5V system with sensors powered by +/-12V, +/-15V, or a 4-20mA current loop. Fault protection to +/-17V prevents the conversion results on a selected channel from being affected by a fault on any other channel. Other features include a 5MHz-bandwidth track/hold, an 8ksps throughput rate, and a choice of an external reference or the internal 4.096V reference.

A 2-wire serial interface allows communication among multiple devices. A hardware shutdown input and two software-compatible power-down modes (standby and full power-down) enable low-current shutdown between conversions. To eliminate start-up delays, the reference buffer remains active during standby mode.

The press release almost suggests that range-switching is separate from some other details and it would have been more accurate to start the 2nd paragraph with "This." However, these are excellent products and continue the theme that is gaining popularity that, in a way, dumbs down the work needed by the design engineer. The +/-16.5-V fault-protected 8-channel multiplexer feeds a programmable-gain amplifier and the 5-MHz track-and-hold before the ADC. The same solution could be put together with discrete parts and you might even be able to do it for slightly less money, but you'd have to sweat a lot more.

I like the 2-wire interface, the internal/external reference choice, the power down modes and the packages chosen. The maximum current the parts might take could be up to 18 mA with bipolar ranges while full shutdown is about 120ưA. Also note that the small-signal bandwidth is directly proportional to the range switching in use and can go down to 1.25 MHz for 0 to 5 V. This are nice products that should do extremely well in automatic testing and battery-powered/medical instrumentation. They are available in either a 24-pin DIP or 28-pin SSOP and are priced at $9.25 in 1000-piece lots