## Overview of ADP7157ARDZ-02-R7 The **ADP7157ARDZ-02-R7** is a high-performance, ultra-low noise, high Power Supply Rejection Ratio (PSRR) Linear Regulator (LDO). It is manufactured by Analog Devices and is specifically designed to provide clean power to noise-sensitive precision analog circuits. --- ### Key Technical Specifications | Parameter | Value / Specification | | :--- | :--- | | **Input Voltage Range** | 2.3 V to 5.5 V | | **Output Voltage (Fixed)** | 1.2 V (indicated by the "-02" suffix) | | **Maximum Output Current** | 1.2 A | | **Noise (10 Hz to 100 kHz)** | 1.6 µV rms | | **PSRR** | >82 dB at 1 kHz; >55 dB at 1 MHz | | **Dropout Voltage** | 120 mV (typical at 1.2 A load) | | **Package Type** | 8-Lead SOIC_N_EP (Exposed Pad) | | **Operating Temperature** | -40°C to +125°C | --- ### Core Features and Benefits 1. **Ultra-Low Noise:** With a noise floor of 1.6 µV rms, it is ideal for powering high-resolution ADCs, DACs, and precision VCOs where power supply noise can degrade system performance. 2. **High PSRR:** It effectively filters out ripples from switching power supplies, ensuring a stable and "quiet" output even in noisy environments. 3. **Adjustable Soft Start:** Allows the user to control the ramp-up time of the output voltage to minimize inrush current. 4. **Precision Enable:** High-accuracy enable threshold allows the part to be used for precise power sequencing. 5. **Thermal Management:** The SOIC_N_EP package features an exposed thermal pad that must be soldered to the PCB to dissipate heat efficiently. --- ### Pin Configuration Summary | Pin No. | Name | Description | | :--- | :--- | :--- | | 1 | **VOUT** | Regulated Output Voltage. | | 2 | **VOUT_S** | Output Voltage Sense input for tight regulation. | | 3 | **VIN** | Regulator Input Supply. | | 4 | **VIN** | Regulator Input Supply (redundant for current capacity). | | 5 | **EN** | Enable Input. Drive high to turn on the regulator. | | 6 | **SS** | Soft Start pin. Connect a capacitor to set start-up time. | | 7 | **REF_FIL** | Reference Filter pin. Connect a capacitor to reduce noise. | | 8 | **GND** | Ground. | | EP | **PAD** | Exposed Pad. Must be connected to Ground for thermal relief. | --- ### Typical Application Circuit To ensure stability and low-noise performance, specific capacitor types are required: ```markdown - Input Capacitor (Cin): 10 µF (Ceramic, Low ESR) - Output Capacitor (Cout): 10 µF (Ceramic, Low ESR) - Noise Reduction Capacitor (Cref_fil): 1 µF - Soft Start Capacitor (Css): Optional (e.g., 10 nF) ```