INA826AIDR

The INA826AIDR from Texas Instruments is a cost-effective precision instrumentation amplifier offering extremely low 200μA power consumption and wide 3V to 36V supply range. A single external resistor sets any gain from 1 to 1000 with excellent gain drift of only 35 ppm/°C max (G>1). The device achieves 104dB min CMRR at G=10 (maintaining 100dB at 5kHz), 150μV max offset voltage, and rail-to-rail output for maximum dynamic range. Input protection circuitry limits input currents to less than 8mA for voltages up to ±40V beyond the supplies, providing robust fault tolerance in industrial environments.

The INA826 uses a current-feedback three-op-amp instrumentation amplifier topology. The input stage employs matched PNP transistors (Q1, Q2) that level-shift the input voltages up by a diode drop, enabling the common-mode range to include the negative supply rail. Internal amplifiers A1 and A2 drive current through the gain-setting resistor RG, and the resulting differential current is mirrored to the output stage A3. The gain equation is G = 1 + (49.4kΩ / RG), where a single external resistor RG sets the gain from 1 (RG open) to 1000 (RG ≈ 49.4Ω). The rail-to-rail output stage maximizes dynamic range at low supply voltages. Input protection uses series resistors and clamping diodes to limit current to 8mA for input voltages up to ±40V beyond the supplies.

• Wheatstone bridge sensor conditioning (load cell, pressure, strain gauge)
• Industrial 4-20mA current loop receiver front-end
• Medical ECG/EEG differential signal acquisition
High-side/low-side current sensing with shunt resistors
• Battery cell voltage monitoring in multi-cell packs