## Overview of the ADR121AUJZ-R2 The **ADR121AUJZ-R2** is a precision, low power, low voltage **Band Gap Voltage Reference** manufactured by Analog Devices. It is designed to provide a stable and accurate output voltage despite variations in input voltage, load, or temperature. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Output Voltage ($V_{out}$)** | 2.500 V | | **Input Voltage Range ($V_{in}$)** | 2.8 V to 18.0 V | | **Output Current Capability** | 5 mA (source) | | **Quiescent Current** | 95 $\mu$A (max) | | **Temperature Coefficient** | 25 ppm/°C (max) | | **Initial Accuracy** | ±0.24% (±6 mV) | | **Package Type** | TSOT-23-5 (UJ-5) | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Functional Description The ADR121 belongs to the ADR12x family of precision references. Unlike traditional Zener-based references, it uses a high-performance **Band Gap** architecture to achieve low dropout and low power consumption. #### Core Features: * **Low Dropout Voltage:** It requires very little "headroom" (only 300mV above the output voltage) to maintain regulation. * **High Stability:** It offers excellent line and load regulation, ensuring that the 2.5V output remains constant even if the supply voltage fluctuates or the load changes. * **No Output Capacitor Required:** While stable with capacitive loads, it does not strictly require an external output capacitor for stability, saving board space. --- ### 3. Pin Configuration (TSOT-23-5) | Pin Number | Name | Function | | :--- | :--- | :--- | | 1 | **DNC** | Do Not Connect | | 2 | **GND** | Ground | | 3 | **DNC** | Do Not Connect | | 4 | **$V_{out}$** | Reference Voltage Output (2.5V) | | 5 | **$V_{in}$** | Input Voltage Supply | --- ### 4. Typical Applications This component is commonly found in precision systems where a reliable "yardstick" for voltage is needed: 1. **ADC Reference:** Providing the reference voltage for 12-bit to 16-bit Analog-to-Digital Converters. 2. **Battery Powered Systems:** Due to its low 95 $\mu$A current draw, it is ideal for handheld devices. 3. **Precision Instrumentation:** Used in sensors and measurement equipment to maintain calibration accuracy. 4. **Process Control:** Used in industrial loops (4-20mA systems) for signal conditioning. --- ### 5. Part Number Breakdown The suffix **AUJZ-R2** provides specific details about the packaging and grade: * **A:** Grade (standard accuracy/temp-co). * **UJ:** TSOT-23 package. * **Z:** RoHS compliant (Lead-free). * **R2:** 7-inch tape and reel (usually containing 250 units).