Op amp has offset calibration to 200 μV
By Paul Rako, Technical Editor -- EDN, May 18, 2009
Microchip Technology’s new MCP651/2/5 operational amplifier targets use in microphone preamplifiers, optical-detector circuitry, digital scales, industrial instrumentation, H-bridge drivers, bar-code scanners, transmission-line drivers, and medical equipment for patient monitoring and ultrasound functions. The device has a maximum supply voltage of 5.5V and a minimum supply voltage of 2.5V. Input-noise voltage density is 7nV/
with a flicker-noise corner of 30 kHz. The device has a 50-MHz-gain-bandwidth product and can output 95 mA of current. The op amp has rail-to-rail outputs and an in input structure that allows input-common-mode voltages 300 mV below the negative-supply voltage. It requires 1.3V of common-mode head room below the positive-supply voltage. The output-slew rate is 30V/μsec, and the supply current is 6 mA. The typical input-bias current is 6 pA, and the maximum is 5000 pA at 125°C.
The device comes in a 10-pin DFN package with an extra pin for the calibration function. When you pull the pin low, the part enters calibration routine using an onboard DAC and memory and delay counters. The pin initiates an offset-voltage correction within 200 msec. Another version comes in a standard eight-pin-package pinout without calibration pins, so it performs the correction only on power-on and within 4 msec. The device has an operating-temperature range of −40 to +125°C. Samples are available now, and the vendor is accepting volume orders. The single-amp MCP651, dual eight-pin MCP652, and dual 10-pin MCP655 cost $1.21, $1.49, and $1.58 (10,000), respectively.
