The INA128 U is an instrumentation amplifier manufactured by Texas Instruments. It is typically used in applications where high-precision signal amplification is required, such as medical instrumentation, industrial process control, and sensor signal conditioning.
Package and Pinout Information
The INA128U is available in a SOIC-8 (Small Outline Integrated Circuit) package, which has 8 pins. Below is a detailed explanation of the pin functions, including a table to list all the pins' functions.
Pin Function Specification for INA128U (SOIC-8 Package) Pin Number Pin Name Pin Function Description 1 V+ Power Supply Pin (positive voltage input, typically +5V to +36V) 2 Ref Reference Input (used to set the output voltage reference, can be tied to ground or a reference voltage) 3 -Input Negative Input (inverting input for differential signal) 4 +Input Positive Input (non-inverting input for differential signal) 5 Output Output Voltage (the amplified output voltage of the differential input signal) 6 -V Power Supply Pin (negative voltage input, typically -5V to -36V) 7 NC No Connection (leave unconnected, reserved for future use) 8 NC No Connection (leave unconnected, reserved for future use)Detailed Pin Function Descriptions:
Pin 1 - V+ (Power Supply Pin): This pin provides the positive power supply for the device. The voltage should typically range from +5V to +36V, depending on the required operational voltage for the circuit. Pin 2 - Ref (Reference Pin): The reference pin is used to set the output reference voltage. In typical applications, this pin can be connected to ground, but it may also be tied to a specific reference voltage to shift the output range of the INA128U. Pin 3 - -Input (Negative Input): This is the inverting input for the instrumentation amplifier. It is one of the differential signal inputs that the INA128U amplifies. Pin 4 - +Input (Positive Input): This is the non-inverting input for the instrumentation amplifier. It is the second differential input signal, which will be amplified relative to the negative input. Pin 5 - Output (Output Pin): The output pin provides the amplified version of the differential input signal. The voltage at this pin is determined by the input signal and the gain set via the external resistor network (if used). Pin 6 - -V (Negative Power Supply Pin): This pin provides the negative power supply for the device. The voltage should typically range from -5V to -36V, depending on the required operational voltage for the circuit. Pin 7 - NC (No Connection): This pin is a "No Connection" pin, meaning it has no function in the circuit. It can be left unconnected. Pin 8 - NC (No Connection): Similar to Pin 7, this is another "No Connection" pin, which is not used in the operation of the INA128U.INA128U Frequently Asked Questions (FAQ)
Q: What is the recommended operating voltage for the INA128U? A: The INA128U can operate with a supply voltage range of +5V to +36V (V+) and -5V to -36V (V-), with the common mode input voltage range extending from -V+ to +V-.
Q: Can the INA128U operate on a single supply voltage? A: Yes, the INA128U can operate on a single supply voltage as long as it is within the specified range of +5V to +36V and -5V to -36V.
Q: What is the function of the Ref pin on the INA128U? A: The Ref pin allows you to set the reference voltage for the output. It can be tied to ground or any desired voltage to shift the output range of the amplifier.
Q: How does the gain of the INA128U get set? A: The gain is set by the external resistor connected between the RG pins (pins 1 and 8 in the SOIC-8 package). The gain formula is: [ \text{Gain} = 1 + \frac{50k\Omega}{R_G} ]
Q: Can I use the INA128U for amplifying small sensor signals? A: Yes, the INA128U is designed for high-precision signal amplification, making it ideal for small sensor signals.
Q: What is the typical output impedance of the INA128U? A: The typical output impedance is very low, typically around 0.1Ω, making it suitable for driving load circuits directly.
Q: Is the INA128U a low-noise amplifier? A: Yes, the INA128U is designed to have low noise, making it suitable for applications requiring high signal integrity.
Q: What is the common-mode rejection ratio (CMRR) of the INA128U? A: The INA128U typically has a CMRR of up to 120dB, which ensures excellent rejection of common-mode signals.
Q: Can the INA128U be used with both AC and DC signals? A: Yes, the INA128U can be used to amplify both AC and DC signals, as long as the input signals are within the common-mode voltage range.
Q: What is the output voltage swing range of the INA128U? A: The output voltage swing range is typically from V- + 0.5V to V+ - 0.5V, depending on the load and supply voltage.
Q: Can the INA128U be used in differential input applications? A: Yes, the INA128U is specifically designed for differential input applications, such as measuring the difference between two sensor outputs.
Q: How do I calculate the gain for the INA128U? A: The gain of the INA128U can be calculated using the formula: [ \text{Gain} = 1 + \frac{50k\Omega}{RG} ] Where ( RG ) is the resistor connected to the RG pin.
Q: What is the input voltage range for the INA128U? A: The input voltage range is typically from -V+ to +V- for both differential inputs, provided the common-mode voltage is within the specified range.
Q: Can I use the INA128U in a system that operates with both positive and negative voltages? A: Yes, the INA128U can operate with both positive and negative voltages, making it ideal for systems requiring dual power supplies.
Q: Does the INA128U have a shutdown mode? A: No, the INA128U does not have a dedicated shutdown mode. Power down the device by turning off the supply voltage.
Q: How can I improve the performance of the INA128U in terms of noise rejection? A: To improve performance, use proper PCB layout techniques, shield the amplifier from noise sources, and ensure that the reference pin is tied to a stable voltage.
Q: What is the temperature range for the INA128U? A: The operating temperature range for the INA128U is typically from -40°C to +85°C.
Q: Can the INA128U be used for high-speed applications? A: While the INA128U is suitable for precision applications, it is not designed for ultra-high-speed applications. It is typically used for signals with relatively low frequencies.
Q: What type of load can the INA128U drive? A: The INA128U can drive a range of loads, but it is optimized for low-impedance loads, typically up to 10kΩ.
Q: What is the noise performance of the INA128U? A: The INA128U has low noise, with a typical input voltage noise density of 4nV/√Hz at 1kHz, making it suitable for sensitive measurements.
This is a detailed explanation of the INA128U instrumentation amplifier, including the pin functions, pinout, and common FAQs. If you need any additional clarifications or details, feel free to ask!
