## Overview of the BP104FASR The **BP104FASR** is a high-speed Silicon PIN Photodiode known for its high sensitivity and fast response times. It is specifically designed for applications involving infrared radiation, featuring a built-in daylight filter to minimize interference from visible light. --- ### Technical Specifications The following table summarizes the key electrical and optical characteristics of the BP104FASR: | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Peak Sensitivity Wavelength** | $\lambda_p$ | 950 | nm | | **Spectral Range of Sensitivity** | $\lambda_{0.1}$ | 800 — 1100 | nm | | **Radiant Sensitive Area** | $A$ | 4.02 | $mm^2$ | | **Open-Circuit Voltage** | $V_O$ | 350 ($E_e=0.5 mW/cm^2$) | mV | | **Short-Circuit Current** | $I_{SC}$ | 38 | $\mu A$ | | **Rise and Fall Time** | $t_r, t_f$ | 20 | ns | | **Reverse Voltage (Max)** | $V_R$ | 20 | V | --- ### Key Electronic Components & Features 1. **PIN Structure**: Unlike standard PN junctions, the PIN photodiode includes an intrinsic (undoped) layer between the P and N layers. This allows for a lower junction capacitance, resulting in significantly **faster switching speeds** and higher sensitivity. 2. **Daylight Filter**: The device is encapsulated in a black epoxy resin. This material acts as a physical band-pass filter that blocks visible light (below 800nm) and allows infrared light to pass through. This makes it ideal for remote controls and outdoor IR sensors. 3. **Surface Mount Technology (SMD)**: The "SR" suffix typically denotes its packaging style, which is designed for automated "Pick and Place" assembly on PCBs. It features a compact, flat-top design. 4. **High Linearity**: The output current is highly linear in relation to the incident light intensity, making it reliable for precision measurement. --- ### Typical Circuit Application When using the BP104FASR, it is commonly operated in **Photoconductive Mode** (reverse biased) to achieve the fastest response times for data transmission. ```python # Simple Transimpedance Amplifier (TIA) logic # Photodiode Current (Ip) -> Voltage (Vout) Vout = Ip * Rf # Rf is the Feedback Resistor ``` #### Usage Scenarios: * **High-speed IR data transmission** (IRDA). * **Industrial Automation**: Light barriers and counters. * **Remote Controls**: TV and Air Conditioning receivers. * **Security Systems**: IR beam detectors. ---