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Analog Angle Article

In-amp arena gets a new player

Chandler, Ariz.—When an op amp just won't suffice for critical sensor signal conditioning and interfacing, you need an instrumentation amplifier, which is a specialized amplifier with the ability to significantly reject common-mode noise and extract tiny signals despite the presence of far larger signals and power-supply imperfections (even 100 dB). [Don’t know what an in-amp is? You should!]

Relatively few analog-IC vendors make in amps, for various reasons, but the supplier list has a new entry: Microchip Technology. Their MCP6N11 Features Microchip’s proprietary mCal technology, which is an on-chip calibration circuit which enables low initial-offset voltage and a means to control offset drift, which results in higher accuracy across time and temperature—both factors which can seriously harm in-amp system-level performance.

The device uses CMOS process technology for low power consumption, while providing a gain bandwidth product of 500 kHz, and it features a hardware-shutdown pin for even more power savings. 1.8V operation allows two 1.5V batteries to be drained beyond typical use, and its rail-to-rail input and output operation enables full-range use, even in low-supply conditions.

Gain of 1, 2, 5, 10, or 100 V/V is set by two user-supplied external resistors. At G = 100, common mode rejection ratio (CMRR) is typically 100dB and can be as high as 115dB, while power supply rejection ratio (PSRR) is 112 dB at G= 100. Supply current is typically 800 µA, and the device operates from a supply of 1.8 to 5.5 V. It is specified over the -40° to +125° C span.

Packaging, availability, and pricing :  The MCP6N11 instrumentation amplifier is available now, in an 8-pin SOIC package and an 8-pin 2mm × 3mm TDFN package, for $1 each in 10,000-unit quantities.

Support and more information : The MCP6N11 is supported by the Wheatstone Bridge Reference Design (part # ARD00354), which is priced at $34.99. For more details, go to http://www.microchip.com/get/KQ76.

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