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Buffered 18bit octal A/D converter

The LTC2358-18, an 18bit, 8channel simultaneous sampling successive approximation register (SAR) A/D converter from Linear Technology – now part of Analog Devices – features integrated picoamp input buffers.

According to the company, the LTC2358-18 brings substantial space and cost savings by eliminating front end signal conditioning circuitry.

Picoamp inputs and 128dB CMRR over a 30VP-P common mode range is said to enable the LTC2358-18 to directly connect to a range of sensors without compromising measurement accuracy.

While converting eight channels at 200ksample/s per channel throughput, the LTC2358-18 provides added flexibility via independently configurable SoftSpan input ranges. Each channel can be programmed on a conversion-by-conversion basis to accept ±10.24V, 0V to 10.24V, ±5.12V, or 0V to 5.12V unipolar, true bipolar, fully differential or arbitrary input signals.

The differential analogue inputs operate over a 30V input common mode range, allowing the A/D converter to directly digitise a variety of signals while simplifying the signal chain design.

The input signal flexibility, combined with ±3.5LSB maximum INL, no missing codes at 18bits, and 96.4dB SNR, makes the LTC2358-18 suitable for high performance industrial process control, test and measurement, power line monitoring and motor control applications.

The converter features a precision internal reference with 20ppm/°C maximum temperature coefficient and an integrated reference buffer capable of accurate one-shot measurements.

In addition, the LTC2358-18 features pin-selectable SPI CMOS and LVDS serial interfaces. The digital output supply range allows the device to communicate with any CMOS logic between 1.8V and 5V.

Together, these I/O interface options enable the device to communicate equally well with legacy microcontrollers and modern FPGAs.

Operating in temperatures ranging from −40 to 125°C, the LTC2358-18 is offered in a 48lead 7 x 7mm LQFP package.

Author
Peggy Lee