To guarantee ultra-low voltage offset and eliminate drift over time and temperature, Maxim Integrated Products’ new instrumentation amplifiers MAX4208/MAX4209H feature the company's patented current-feedback architecture, a spread-spectrum autozeroing technique. The new autozeroing technology constantly measures and corrects the input offset voltage, thereby eliminating drift over time and temperature. The input offset voltage is 20 microvolts (maximum) at +25 °C, and 40 microvolts (maximum) over the -40 °C to +125 °C temperature range. The technology's compact design allows the MAX4208/MAX4209H to fit in a small, 3 mm x 5 mm microMAX package, making them suitable for use in a wide range of applications. The amplifiers can monitor the low-voltage, power-supply currents of the core, ASIC and microprocessor in laptop computers. The amplifiers are also aimed at automotive, industrial, and medical instrumentation.

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The MAX4208/MAX4209H feature an innovative, two-transconductance-amplifier architecture. This indirect current-feedback architecture allows designers to use the full dynamic range of input differential signals, even when the common-mode voltages are close to, or below, ground, said Maxim. This true low-side sensing capability is not offered by the common three-operational-amplifier approach, asserted Maxim.

The MAX4208/MAX4209H offer true ground sensing and an input common-mode voltage range of -0.1 V to VDD - 1.3 V. CMRR is guaranteed to be at least 106 dB.

The MAX4208 features an adjustable gain, with the gain set by the ratio of two external resistors. The MAX4209H uses internal laser-trimmed resistors to set a fixed gain of 100x. And offers a maximum gain error of ±0.25% at +25 °C , ±0.3% up to +85 °C, and ±0.35% over the entire -40 °C to +125 °C temperature range.

It also include an autozero reference-buffer amplifier, which allows the output to be level-shifted to VDD/2 using a simple resistor-divider or an external reference input with minimum loading error. This buffer increases system accuracy and is useful for bipolar signals in single-supply applications. The high-impedance inputs are optimized for small-signal differential voltages (±100 mV). All devices operate from a single 2.85 V to 5.5 V supply (or ±1.425 V to ±2.75 V dual supplies) with ground-sensing capability and ultra-low, 1pA (typ) CMOS-input bias currents.

Samples of the MAX4208/MAX4209H are available now. The MAX4208 and MAX4209H are priced at $1.65 each, in 1000 and higher pieces.