## ADP125ACPZ-R7: Technical Overview The **ADP125ACPZ-R7** is a high-performance, low quiescent current, linear regulator (LDO) manufactured by **Analog Devices**. It is designed specifically to provide a stable output voltage from a wide input range, making it ideal for battery-powered and space-constrained applications. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Type** | Adjustable Low Dropout Regulator (LDO) | | **Input Voltage Range** | 2.3 V to 5.5 V | | **Output Voltage Range** | 0.8 V to 5.0 V (Adjustable) | | **Maximum Output Current** | 500 mA | | **Dropout Voltage** | 130 mV @ 500 mA Load | | **Quiescent Current ($I_q$)** | 45 µA (Typical at no load) | | **Package Type** | 6-lead LFCSP (2mm x 2mm) | | **PSRR** | 60 dB at 100 kHz | --- ### 2. Functional Features * **Adjustable Output:** Unlike fixed-voltage regulators, the ADP125 uses an external resistor divider to set the output voltage, providing design flexibility. * **Low Dropout (LDO):** The very low dropout voltage (130mV) allows the device to maintain regulation even when the input voltage is very close to the desired output voltage. * **Enable Input:** Includes a dedicated precision enable pin to power down the device, reducing current consumption to less than 1 µA in shutdown mode. * **Stability:** Optimized for stable operation with small, low-ESR ceramic capacitors (minimum 1 µF). --- ### 3. Pin Configuration (6-Lead LFCSP) | Pin No. | Mnemonic | Description | | :--- | :--- | :--- | | 1 | **VIN** | Regulator Input Supply. | | 2 | **GND** | Ground. | | 3 | **EN** | Enable Input. Drive high to turn on; low to turn off. | | 4 | **ADJ** | Adjustable Input. Connect to resistor divider to set $V_{out}$. | | 5 | **NC** | No Connection (internally not connected). | | 6 | **VOUT** | Regulated Output Voltage. | | EP | **Exposed Pad** | Should be soldered to the PCB ground plane for thermal dissipation. | --- ### 4. Typical Application Circuit To set the output voltage, use the following formula: `VOUT = 0.8V * (1 + R1 / R2)` ```text Input (VIN) ----[ C1: 1uF ]----| ADP125 |----[ C2: 1uF ]---- Output (VOUT) | | | ADJ |----[ R1 ]----| | | | |________| [ R2 ] | Ground ``` --- ### 5. Common Applications * **Mobile Phones:** Powering digital cores or analog peripherals. * **Portable Medical Equipment:** Heart rate monitors and diagnostic tools. * **Post-Regulation:** Cleaning up noise from switching DC-DC converters. * **Sensor Power:** Providing clean, stable power to sensitive MEMS or imaging sensors.