The **ADP161AUJZ-R7** is a high-performance, low quiescent current, low dropout (LDO) linear regulator manufactured by Analog Devices. It is specifically designed for portable and battery-powered applications where power efficiency and space are critical. --- ## 1. Key Specifications | Feature | Specification | | :--- | :--- | | **Input Voltage Range** | 2.2V to 5.5V | | **Output Voltage** | 3.3V (Fixed) | | **Maximum Output Current** | 150 mA | | **Dropout Voltage** | 60 mV at 150 mA load | | **Quiescent Current** | 45 µA (at no load) | | **Shutdown Current** | < 1 µA | | **Package Type** | 5-Lead TSOT (UJZ suffix) | | **PSR (Power Supply Rejection)** | 72 dB at 1 kHz | --- ## 2. Core Functional Components The internal architecture of the ADP161 consists of several critical electronic stages: ### A. Pass Element (P-Channel MOSFET) Unlike bipolar regulators, the ADP161 uses a **P-channel MOSFET** as its pass device. This allows for extremely low dropout voltages, as the device acts like a resistor between the input and output when the input voltage approaches the target output voltage. ### B. Internal Reference & Error Amplifier The device includes a high-precision internal voltage reference. The **Error Amplifier** constantly compares a fraction of the output voltage (via a resistor divider) against this reference. If the output drops, the amplifier increases the gate drive to the MOSFET to restore the voltage. ### C. Protection Circuitry * **Thermal Overload Protection:** Automatically shuts down the device if the junction temperature exceeds approximately 150°C. * **Short-Circuit Protection:** Limits the output current to prevent damage during a fault condition. * **Under-Voltage Lockout (UVLO):** Ensures the device stays off until the input voltage reaches a valid threshold (approx. 2.0V). --- ## 3. Pin Configuration | Pin No. | Name | Description | | :--- | :--- | :--- | | 1 | **VIN** | Regulator Input Supply. | | 2 | **GND** | Ground reference. | | 3 | **EN** | Enable Input. High = On, Low = Off. | | 4 | **NC/ADJ** | No Connect (for fixed versions) or Adjust (for adjustable versions). | | 5 | **VOUT** | Regulated Output Voltage. | --- ## 4. Application Logic The ADP161 is optimized for **Stability with Ceramic Capacitors**. It requires small 1 µF ceramic input and output capacitors to maintain stability. This reduces the overall PCB footprint compared to older LDOs that required bulky electrolytic or tantalum capacitors. ---