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FROM EDN EUROPE: Reprogrammable analogue-input chip cuts component count

You can cut the component count in the analogue front end of data-acquisition systems and other circuitry that interfaces to real-world signals with Lattice Semiconductor's ispPAC30 chip. The device is the latest member of Lattice's family of programmable analogue parts. Others in the series include ICs for general analogue-signal-processing functions and parts dedicated to filtering.

The ispPAC30 provides four instrumentation amplifiers with two associated analogue multiplexers, two precision references, and two output amplifiers, plus a "pool" of configurable routing resources. You can configure the interconnection of these elements, including the option of single-ended- or differential-amplifier inputs, and you can set all the required parameters, such as gain, offset, and filtering coefficients, to perform a variety of signal-conditioning functions. The performance envelope includes bandwidth as high as 1.5 MHz. Like other ispPAC devices, the filtering functions are continuous-time, and the response extends down nearly to dc. The device also features high-resolution gain setting in 0.01 steps and rail-to-rail outputs, and low-power operation includes a standby mode that uses only 10 µA. New in the ispPAC30 is the use of both EEPROM and SRAM configuration memory; you can store a power-up configuration in the EEPROM and then dynamically reconfigure the device using the SRAM. Settling time for a reconfiguration cycle is tens of microseconds. Dynamic reconfiguration can cover parametric settings only (changing gain settings, for example) or can involve a switch to a new circuit layout to perform a different function.

You can use the device as a front end to a wide variety of ADCs from multiple manufacturers, and, at $7 (1000), it gives you a smaller bill-of-materials cost for analogue components than one assembled from conventional parts. You configure the device with a Windows-based package and download the configuration file directly from the PC's parallel port; for production purposes, a conventional in-system-programming process loads a programming image. A development system, including an evaluation board, sells for $149.

Lattice Semiconductor, +44 1932 582941, www.latticesemi.com.