OP2177ARMZ

The OP2177ARMZ is a high-precision dual operational amplifier from Analog Devices, part of the OPx177 family that includes single (OP1177), dual (OP2177), and quad (OP4177) versions. The ‘ARMZ’ suffix indicates the MSOP-8 (Mini Small Outline Package) surface-mount package. Designed for precision analog applications, the OP2177 combines exceptional DC accuracy with low noise and low power consumption. The input offset voltage of just 25µV typical (60µV maximum) and offset drift of 0.2µV/°C typical (0.7µV/°C max) make it suitable for precision measurement applications across wide temperature ranges. The OP2177 uses a bipolar input stage with bias current cancellation to achieve input bias currents of just 2nA maximum – significantly lower than typical precision bipolar op-amps. This low bias current, combined with low voltage noise (7.9nV/√Hz) and low current noise (0.2pA/√Hz), provides excellent noise performance for a wide range of source impedances. A unique feature of the OP2177 is its input overvoltage protection. Internal 500Ω series resistors on the inputs allow input signals to exceed the supply voltages by several volts without causing phase reversal or damage, a valuable feature in industrial and sensor applications where input overload conditions can occur. The device operates from dual supplies of ±2.5V to ±15V, consuming only 400µA per amplifier. The output is unity-gain stable and can drive capacitive loads of over 1000pF without oscillation. With its compact MSOP-8 package and -40°C to +125°C operating temperature range, the OP2177ARMZ is well-suited for space-constrained industrial and automotive precision applications.

The OP2177ARMZ is a precision voltage-feedback operational amplifier using a bipolar input stage with advanced features for high accuracy: 1) Input Stage: The differential input stage uses NPN bipolar transistors with an active load. A bias current cancellation circuit reduces the effective input bias current to the nanoampere range – much lower than would be expected from the input transistor base currents alone. Internal 500Ω series resistors protect the input transistors from overvoltage conditions and help prevent phase reversal when inputs exceed the supply rails. 2) Gain Stage: The intermediate gain stage provides high voltage gain using active loads. The combination of multiple gain stages achieves the very high open-loop gain of 2,000 V/mV (126dB) typical. 3) Output Stage: A class AB push-pull output stage provides low output impedance and can source/sink up to ±10mA. The output is stable with capacitive loads up to 1000pF without external compensation, thanks to internal frequency compensation. 4) Frequency Compensation: Internal Miller compensation ensures unity-gain stability. The compensation network is optimized to provide 1.3MHz of gain-bandwidth product while maintaining stability. 5) Precision Trimming: Laser trimming during manufacturing is used to trim the input offset voltage to very low levels, achieving the 25µV typical and 60µV maximum specifications. This trimming also optimizes the offset drift characteristics. 6) Supply Operation: The OP2177 operates from dual supplies of ±2.5V to ±15V (or single supply of 5V to 30V). The PSRR of 125dB ensures that supply voltage variations have minimal effect on the input offset voltage. 7) Noise Performance: With 7.9nV/√Hz voltage noise density and 0.2pA/√Hz current noise density, the total noise seen at the output depends on the application’s source resistance. The optimum source resistance for lowest total noise is approximately 40kΩ (where voltage and current noise contributions are equal). 8) No Phase Reversal: Unlike many op-amps that can exhibit output phase reversal when inputs are overdriven, the OP2177’s input stage design prevents this phenomenon, ensuring predictable behavior even under overload conditions.

MSOP-8 pinout (RM suffix). Standard dual op-amp pin configuration, compatible with industry-standard dual op-amp pinouts.

• Precision instrumentation amplifiers and measurement circuits
• Thermocouple, RTD, and strain gauge signal conditioning
• Precision active filters (low-pass, high-pass, band-pass)
• Shunt current and voltage sensing for power monitoring
• Wireless base station and optical network control circuits
• High-resolution ADC front-end buffer and signal conditioning
• Precision voltage and current references
• Portable and battery-operated test equipment