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Analog Angle Article

ADC drivers push power, THD down; bandwidth, slew, precision up

Analog signal-chain designers know that in many situations, the analog/digital converter (ADC) driver is as critical to meeting design objectives as the converter itself, as it (among other things) matches the source the ADC input while isolating the former from subtle input changes in the latter. The OPAx836 series of single- and dual-channel driver op amps from Texas Instruments is designed to ease the challenge and improve the result for portable, low- to medium-speed instrumentation in industrial and medical applications.

It does this by reducing power, and THD (total harmonic distortion), noise, and size specifications while improving the bandwidth, precision, and slew rate factors, commensurate with 12-, 14-, and 16-bit situations.

•P ower consumption is 1 mA per channel while providing 205 MHz of bandwidth for driving low-power SAR and delta-sigma ADCs.

205 MHz bandwidth with a slew rate of 560 V/µs, THD of 130 dBc and noise of 4.6 nV/vHz achieve what the vendor claims is the highest linearity, signal-to-noise ratio and spurious-free dynamic range in its class, resulting in enhanced sensitivity and data converter performance.

Typical input-offset voltage of 0.065 µV and drift of 1.1 mV/°C.

Ultra-small 2×2-mm WQFN package with integrated gain setting resistors reduces board space up to 75 percent, compared to the competitive offerings, says the vendor.

Tools and support: Evaluation modules (EVMs) are available today for the single-channel OPA836 (OPA836IDBVEVM) and dual OPA2836 (OPA2836IDGSEVM) for a suggested retail price of $99 and $149, respectively.  A reference design for the OPA836 is also available with the TI ADS7945 (ADS7945EVM-PDK) and ADS7946 (ADS7946EVM-PDK) converters.PSpice and TINA-TI Spice models and TINA-TI reference designs are also available for both devices.

Pricing and availability : Samples and production quantities of the single-channel OPA836 are available in two package options: 1) a 10-pin, 2 × 2-mm WQFN, or 2) a 6-pin, 3 × 3-mm SOT23. Suggested retail pricing for 1,000 units is $0.90. The dual OPA2836 is available today in three package options: 1) an 8-pin, 4 × 5-mm SOIC, 2) a 10-pin, 3 × 3-mm MSOP, or 3) a 10-pin, 2 × 2-mm WQFN. Suggested retail pricing for 1,000 units is $1.50.

For more information : Download the data sheet at www.ti.com/opax836ds-pr, or watch the video at www.ti.com/opax836v-pr.

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