Tuesday, December 01, 2009

LTC2656 DAC Has 0.1 Percent Gain Error


Linear Technology has introduced the LTC2656, a 16-bit octal digital-to-analogue converter (DAC) that offers +/-4LSB INL maximum over temperature. The combination of 0.1 per cent (max) gain error and +/-2mV (max) offset error ensure that LTC2656 remains accurate near the supply rails and provides the user with a wider effective-output range.

The LTC2656's precision specifications make it suitable for multichannel open- and closed-loop systems typically found in communication systems, industrial process control, automated test equipment (ATE) and programmable logic controllers. The converter integrates a precision reference that achieves 2ppm/C typical and 10ppm/C maximum temperature coefficient. By integrating the reference in its 20-pin 4 x 5mm QFN and TSSOP packages, the LTC2656 offers further space reduction for densely packed circuit boards.

Operating from a single 2.7 to 5.5V supply, supply current is 375uA per DAC with the reference activated. The LTC2656 offers 8.5us settling time for a half-scale step and less than 1nVs crosstalk, resulting in minimal disturbance between DAC channels. The DAC communicates via a four-wire SPI-compatible interface up to 50MHz and offers a range of options to meet application-specific requirements. Designers can choose between 16 or 12-bit resolution and an internal 1.25 or 2.048V reference, which produces a full-scale output voltage of 2.5 or 4.096V.

Alternatively, an external reference up to half the supply voltage can be for rail-to-rail operation. The LTC2656 also includes a hardware option to power up the DAC outputs at zero scale or midscale. 16- and 12-bit DACs are available in production volumes along with the LTC2657, an I2C-compatible 16-bit octal DAC.

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