The **ADP2138ACBZ-1.5-R7** is a high-efficiency, low quiescent current, step-down (buck) DC-to-DC converter manufactured by Analog Devices. It is designed for portable applications where space and power efficiency are critical. --- ## 1. Key Specifications The following table summarizes the primary electrical characteristics of the device: | Parameter | Specification | | :--- | :--- | | **Manufacturer** | Analog Devices | | **Output Voltage** | 1.5 V (Fixed) | | **Input Voltage Range** | 2.3 V to 5.5 V | | **Output Current** | 800 mA (Maximum) | | **Switching Frequency** | 3 MHz | | **Package Type** | 6-ball WLCSP (Wafer Level Chip Scale Package) | | **Operating Temperature** | -40°C to +125°C | --- ## 2. Core Features The ADP2138 series is popular in mobile electronics due to several advanced internal features: * **High Efficiency:** Uses a synchronous rectification internal switch to achieve up to 95% efficiency, extending battery life. * **3 MHz Switching Frequency:** The high frequency allows the use of tiny, low-profile inductors and ceramic capacitors, reducing the overall PCB footprint. * **Power Saving Mode:** Automatically switches from PWM (Pulse Width Modulation) to PSM (Power Save Mode) at light loads to maintain high efficiency. * **Internal Compensation:** Simplifies the design process by minimizing the need for external components. * **Protection Circuitry:** Includes undervoltage lockout (UVLO), soft start, thermal shutdown, and short-circuit protection. --- ## 3. Pin Configuration & Application The device is housed in a very small **0.5 mm pitch WLCSP** package. Below is a typical application schematic overview: ### Typical Component Values | Component | Recommended Value | | :--- | :--- | | **Input Capacitor ($C_{IN}$)** | 4.7 µF (Ceramic) | | **Output Capacitor ($C_{OUT}$)** | 10 µF (Ceramic) | | **Inductor ($L$)** | 1.0 µH | ### Common Applications 1. **Mobile Phones:** Powering baseband processors or I/O rails. 2. **Wearables:** Smartwatches and fitness trackers requiring small footprints. 3. **Digital Cameras:** Powering image sensors or internal logic. 4. **Portable Medical Devices:** Handheld diagnostic tools. --- ## 4. Part Number Breakdown Understanding the suffix codes helps in procurement: * **ADP2138:** Base model number. * **ACBZ:** Package code (WLCSP). * **1.5:** Fixed output voltage (1.5 Volts). * **R7:** Packaging format (7-inch reel, typically containing 3,000 units).