18-bit, 8-independent-channel multiplexed SAR ADC

February 24, 2016 // By Graham Prophet
LTC2335-18 is an 18-bit, 8-channel 1 Msps multiplexed input successive approximation register (SAR) ADC with independently configurable input ranges. Each SoftSpan input can be software configured on a conversion-by-conversion basis to accept ±10.24V, 0V to 10.24V, ±5.12V or 0V to 5.12V true bipolar input signals.

An on-chip sequencer allows the LTC2335-18 to be programmed to cycle through a sequence of channels and ranges without further user intervention. The differential analogue inputs operate over a wide -16.5V to 34V input common mode range, allowing the ADC to directly digitise a variety of signals to simplify signal-chain design. The input signal flexibility, combined with 96.7 dB SNR and 1 Msps throughput, suits the LTC2335-18 for high performance industrial process control, test and measurement, power line monitoring and instrumentation applications.

The LTC2335-18 features a precision internal reference with 20 ppm/°C maximum temperature coefficient and an integrated reference buffer capable of accurate one-shot measurements, providing space savings in densely packed circuit boards. Optionally, an external 5V reference may be used to expand the analogue input range to ±12.5V. The device dissipates 180 mW when converting at 1 Msps, and features nap and power-down modes to reduce power dissipation at slower throughputs.

The LTC2335-18 features pin-selectable SPI CMOS and LVDS serial interfaces. The wide digital output supply range allows the device to communicate with any CMOS logic between 1.8V and 5V. The serial LVDS mode offers low noise, high speed communications over greater distances using differential signalling. Together, these I/O interface options enable the LTC2335-18 to communicate equally well with legacy microcontrollers and modern FPGAs.

The LTC2335-18 joins a high performance family of multichannel 18-/16-bit SAR ADCs with true bipolar ±10.24V simultaneous sampling inputs (LTC2348). All specifications are guaranteed over the extended -40°C to 125°C temperature range. The LTC2335-18 is available now in a 48-lead, 7 x 7mm LQFP package for (1,000).

Linear Technology; www.linear.com/product/LTC2335-18