The INA121U/2K5 is a precision instrumentation amplifier manufactured by Texas Instruments (TI). It is typically used in applications that require accurate differential voltage measurements, such as in industrial, medical, and sensor interface circuits. The device is part of the INA121 series, which is known for its low power consumption and high-precision measurement capabilities.
Pin Function Specifications and Circuit Principle
The INA121U/2K5 is packaged in a 8-pin SOIC (Small Outline Integrated Circuit) package, which is commonly used for surface-mount technology (SMT) applications. Below is the pinout of the INA121U/2K5 with a detailed explanation of each pin function:
Pin Number Pin Name Pin Function Description 1 REF The reference pin sets the output reference voltage. By applying a voltage at this pin, you can shift the output voltage accordingly. It allows for easier interfacing with single-supply systems. The typical range for the REF pin is from 0V to V+ voltage. 2 -IN Inverting input of the amplifier. This is one of the two differential input pins. It receives the signal that is to be subtracted from the non-inverting input. 3 +IN Non-inverting input of the amplifier. This is the other differential input pin. The signal applied to this input will be amplified relative to the signal applied to the -IN pin. 4 V- Negative supply pin for the operational amplifier. In typical applications, this would be connected to ground in a single-supply configuration or to a negative voltage in a dual-supply configuration. 5 OUT The output of the INA121U/2K5 amplifier. This pin provides the amplified differential voltage signal from the inputs, and the output voltage is proportional to the difference between the two input signals. 6 V+ Positive supply pin for the operational amplifier. This pin is typically connected to a positive supply voltage in single-supply or dual-supply configurations. 7 NC No connection pin. This pin is not internally connected to the chip and is typically left floating or unused. 8 NC Another no connection pin. Like pin 7, it is not used in the device's internal circuitry.Detailed Pin Function List
The INA121U/2K5 has 8 pins in total, and each pin has a specific function that is important for its operation within a circuit. A detailed list is provided above.
Frequently Asked Questions (FAQs)
What is the typical application for the INA121U/2K5? The INA121U/2K5 is typically used in applications that require accurate differential voltage measurement, such as sensor signal conditioning, medical devices, and industrial measurement systems. What is the voltage range for the REF pin? The REF pin typically operates within a voltage range of 0V to V+. What is the purpose of the V- pin? The V- pin is the negative supply pin. It is typically connected to ground in single-supply systems or to a negative voltage source in dual-supply configurations. Can I use a single-supply voltage with the INA121U/2K5? Yes, the INA121U/2K5 can be powered with a single-supply voltage. In this case, V+ is connected to a positive voltage (e.g., 5V), and V- is connected to ground. What is the maximum input voltage for the INA121U/2K5? The maximum input voltage should not exceed the supply voltages (V+ and V-), and the voltage difference between the two input pins should not exceed the device’s specified input range. How do I set the gain for the INA121U/2K5? The gain of the INA121U/2K5 is set using an external resistor between pins 1 (REF) and 8 (NC), according to the gain equation specified in the datasheet. What is the typical output voltage range for the INA121U/2K5? The typical output voltage range for the INA121U/2K5 depends on the supply voltages and the input signal. The output voltage will be proportional to the differential input voltage and gain. Can the INA121U/2K5 be used in high-speed applications? The INA121U/2K5 is not designed for high-speed applications. It is optimized for precision and low noise, making it suitable for sensor and low-frequency applications. What is the recommended input impedance for the INA121U/2K5? The recommended input impedance should match the needs of the application, but typically it is high to ensure minimal loading on the signal source.What is the maximum power supply voltage for the INA121U/2K5?
The INA121U/2K5 can operate with a maximum supply voltage of 36V (with V+ and V- being ±18V), though the typical voltage used is ±15V or single 5V supply.What is the typical offset voltage of the INA121U/2K5?
The INA121U/2K5 has a low offset voltage specification, typically in the microvolt range, which helps in maintaining accuracy in the output signal.Can the INA121U/2K5 be used for bridge sensor applications?
Yes, the INA121U/2K5 is well-suited for interfacing with bridge sensors, as it offers high input impedance and low offset, making it ideal for precise sensor measurements.How do I filter noise from the output of the INA121U/2K5?
Noise filtering can be achieved by using external filtering components, such as capacitor s or low-pass filters , on the output of the INA121U/2K5.Is the INA121U/2K5 available in different package types?
The INA121U/2K5 is available in the SOIC-8 package, but other versions of the INA121 family may be available in different packages.What is the typical power consumption of the INA121U/2K5?
The INA121U/2K5 has a low power consumption, typically around 500µA for a single-supply operation.Can the INA121U/2K5 be used for differential current measurement?
Yes, the INA121U/2K5 is suitable for differential voltage measurement, which can be used in applications like current sensing with a shunt resistor.What is the temperature range of the INA121U/2K5?
The operating temperature range for the INA121U/2K5 is typically from -40°C to 125°C, making it suitable for a wide range of environments.Can the INA121U/2K5 be used in automotive applications?
Yes, the INA121U/2K5 is rated for industrial applications and can be used in automotive applications where precision measurement is required.Is the INA121U/2K5 RoHS compliant?
Yes, the INA121U/2K5 is RoHS compliant, meaning it is free from hazardous substances like lead and can be used in environmentally friendly applications.What are the key features of the INA121U/2K5?
Key features include precision, low offset, high input impedance, low power consumption, and a wide input voltage range, making it suitable for sensor applications and differential signal processing.This completes the detailed explanation of the INA121U/2K5's pin function specifications, packaging details, pinout, and FAQ section.