Current-sense amp integrates precision shunt resistor, in single package

July 10, 2015 // By Graham Prophet
Texas Instruments says it is making, “high-accuracy measurement more attainable with the first current-sense amplifier to integrate a high-precision, low-drift 2 mΩ shunt resistor,” - the device can cut calibration effort, system cost, and footprint for test and measurement, communications load monitoring, and power supplies.

For highly accurate measurements over a wide temperature range, TI’s INA250 integrates the shunt resistor with a bi-directional, zero-drift current-sense amplifier to support both low-side and high-side implementations. It enables high-accuracy current measurements at common-mode voltages that can vary from 0 to 36V. The family of devices will be available in four output scales; 200, 500 and 800 mV/A, and 2 V/A; the maximum current through the shunt resistor is 10A at the full rated temperature of 125C, or 15A at up to 85C. Its accuracy and low drift reduce or may even eliminate designers' calibration effort for many systems. This integration also enables lower system cost and a smaller board footprint compared to alternative solutions.

Test and measurement designers can achieve required performance levels and potentially eliminate calibration while reducing cost to around one-quarter of prior configurations, TI asserts. High-performance enterprise and telecom equipment designers can achieve distributed measurement to maximise system efficiency and enhance system management.

The INA250 current-sense amplifier is, TI adds, the most accurate integrated solution available – the integrated 2-milliOhm shunt resistor offers 0.1% tolerance as well as low drift of 15 pmm/°C from -40 to 125C. The amplifier offers offset current of 12.5 mA with temperature drift of 250 µA/C and gain drift of 30 ppm/C. The integrated packaging technology ensures an optimised Kelvin connection between the IC and the resistor.

The amplifier enables a maximum error of 0.75% over the temperature range of -40 to +125C. Board footprint can be reduced to one-third that of alternative solutions by integrating the shunt resistor. Maximum power consumption of 300 µA minimises the load that the measurement methodology adds to the system.

The INA250 evaluation module (EVM) is available for $49. INA250 TINA-TI and TINA-TI Spice models are available for download.

The INA250 current-sense amplifier comes in a 5 x 6.4-mm thin-shrink small outline package (TSSOP) at $1.40 (1000).

Texas Instruments;  www.ti.com/ina250-pr-eu