OPA227U-2K5 Detailed explanation of pin function specifications and circuit principle instructions

The model " OPA227U/2K5 " is a precision operational amplifier (op-amp) produced by Texas Instruments. It belongs to the OPA227 series of operational amplifiers, which are well-known for their low noise, low offset voltage, and high precision in various applications.

Packaging and Pin Function Specifications

The OPA227U is typically available in a Dual In-line Package (DIP-8) or Surface-Mounted Package (SO-8). The most common package for this part is the DIP-8, which has 8 pins. Below is a detailed explanation of the pin functions and circuit principles for the DIP-8 package.

Pin Function List for OPA227U/2K5 (DIP-8) Pin Number Pin Name Pin Function Description Pin 1 Offset Null This pin is used to adjust the offset voltage of the operational amplifier. It is connected to an external potentiometer or other means to provide offset adjustment. Pin 2 Inverting Input (−) This is the inverting input terminal of the op-amp. The signal applied here will be inverted in phase and amplified based on the circuit configuration. Pin 3 Non-Inverting Input (+) This is the non-inverting input terminal. The input signal applied here will be passed through without inversion but will be amplified based on the circuit design. Pin 4 V− (Negative Supply) This is the negative supply voltage terminal. The op-amp operates within the voltage limits specified between V+ and V−. This pin connects to the negative power supply in a dual supply configuration. Pin 5 Offset Null Similar to Pin 1, this pin is used for fine adjustment of the input offset voltage. In some configurations, Pin 1 and Pin 5 can be connected to adjust the offset voltage. Pin 6 Output This is the output terminal where the amplified signal is available. The output voltage depends on the input voltage and the gain set by the surrounding components in the op-amp circuit. Pin 7 V+ (Positive Supply) This is the positive supply voltage terminal. The op-amp operates within the voltage limits specified between V+ and V−. This pin connects to the positive power supply in a dual supply configuration. Pin 8 NC (No Connection) This pin is not connected to any internal circuitry of the op-amp. It can be left unconnected in most applications.

OPA227U Pin Function Specifications Table

Pin Number Pin Name Function Description 1 Offset Null Adjusts the input offset voltage using an external potentiometer. 2 Inverting Input (−) This is where the signal enters and is inverted by the operational amplifier. 3 Non-Inverting Input (+) This is where the signal enters and is amplified without inversion. 4 V− (Negative Supply) Connects to the negative power supply voltage. The OPA227U operates within the specified voltage range. 5 Offset Null This pin helps fine-tune the offset voltage adjustment. 6 Output The output terminal where the amplified signal is generated. 7 V+ (Positive Supply) Connects to the positive power supply voltage. 8 NC (No Connection) Unused pin, typically left unconnected.

Circuit Principle and Operating Conditions

The OPA227U operates as a low-offset, low-noise operational amplifier. The key feature of this device is its extremely low input offset voltage, making it suitable for precision applications such as instrumentation, data acquisition systems, and high-fidelity audio amplifiers.

The device has a dual power supply configuration—meaning it requires both a positive and a negative voltage source. The range for the supply voltage is typically ±2V to ±18V for optimal performance, with the output being a faithful representation of the amplified input signal based on the gain set by external resistors.

20 Common FAQs about OPA227U

1. What is the typical application for the OPA227U?

Answer: The OPA227U is used in precision measurement circuits, instrumentation, audio systems, and sensors that require low noise and low offset voltage.

2. How do I adjust the offset voltage in the OPA227U?

Answer: You can adjust the offset voltage using the Offset Null pins (Pins 1 and 5) with an external potentiometer to achieve zero offset.

3. What is the operating voltage range of the OPA227U?

Answer: The OPA227U operates with a supply voltage range from ±2V to ±18V for dual supply configurations.

4. Can the OPA227U be used with a single supply voltage?

Answer: Yes, the OPA227U can be used with a single supply voltage, but care must be taken to ensure proper input voltage ranges.

5. What is the power consumption of the OPA227U?

Answer: The OPA227U typically consumes around 500µA of current from the power supply, depending on the operating conditions.

6. What is the input impedance of the OPA227U?

Answer: The input impedance of the OPA227U is typically very high, around 10^12 ohms, making it suitable for high-impedance signal sources.

7. What is the output impedance of the OPA227U?

Answer: The output impedance is low, typically around 10 ohms, which is suitable for driving low-impedance loads.

8. What is the output voltage swing range for the OPA227U?

Answer: The output voltage swing typically ranges from V− + 1.5V to V+ − 1.5V, depending on the load and supply voltages.

9. What is the temperature coefficient of the input offset voltage?

Answer: The input offset voltage temperature coefficient is typically 0.3µV/°C, which is very low and contributes to the stability of the amplifier over temperature variations.

10. How do I implement a feedback loop with the OPA227U?

Answer: A feedback loop is typically implemented by connecting external resistors between the output and input pins (Pins 2 and 3) to set the gain of the amplifier.

11. What is the common-mode rejection ratio (CMRR) of the OPA227U?

Answer: The CMRR of the OPA227U is typically 130dB, which ensures that common-mode signals are rejected with minimal impact on the output.

12. Can I use the OPA227U for high-speed applications?

Answer: The OPA227U is a precision op-amp optimized for low noise and low offset, but its bandwidth (typically 1MHz) limits its use in high-speed applications.

13. What is the typical slew rate of the OPA227U?

Answer: The typical slew rate of the OPA227U is 0.3V/µs, which is relatively slow compared to high-speed op-amps.

14. Is the OPA227U suitable for audio applications?

Answer: Yes, the OPA227U is well-suited for high-fidelity audio applications due to its low noise and low distortion.

15. What is the input bias current for the OPA227U?

Answer: The input bias current is typically 10pA, which is very low and helps to minimize errors in precision circuits.

16. Can the OPA227U be used in automotive applications?

Answer: Yes, it can be used in automotive applications, particularly for sensor interfacing or precision signal conditioning.

17. What type of capacitor s should be used with the OPA227U for stability?

Answer: A 0.1µF ceramic capacitor is often used for decoupling the power supply pins (V+ and V−) to reduce noise and improve stability.

18. How does the OPA227U perform in low-voltage systems?

Answer: The OPA227U can operate down to ±2V, making it suitable for low-voltage systems where precision is still needed.

19. What is the output short-circuit protection of the OPA227U?

Answer: The OPA227U is internally protected against short circuits at the output, but continuous short circuits can lead to thermal damage.

20. How do I choose the appropriate gain for the OPA227U?

Answer: The gain is determined by the external resistor network around the op-amp. Choose the resistor values according to the required amplification and stability criteria for your application.

These detailed specifications, pin descriptions, and FAQs should give a complete understanding of the OPA227U's functionality and help in its effective use in various applications.