Sensores ópticos

OPT211

OPT211 - Monolithic Photodiode + Transimpedance Amp | Burr-Brown (TI)

The Burr-Brown OPT211 is a monolithic photodiode with on-chip FET-input transimpedance amplifier, providing wide bandwidth at very high gains. It integrates a silicon photodiode and a low-noise FET-input op-amp transimpedance stage in a single 8-pin DIP package (suffix P), with uncommitted input and feedback nodes for application-specific feedback networks. The device operates from +/-2.25 V to +/-18 V supplies. A monolithic photodiode plus transimpedance amplifier (TIA) combines a light-sensing element and a current-to-voltage conversion stage on one die. Photodiodes generate a small photocurrent proportional to incident light; a transimpedance amplifier converts that current into a usable voltage with high gain and low noise, which is critical in optical sensing front-ends. This category sits within optical sensors and front-end analog ICs, used wherever light must be measured precisely, from scientific instruments to industrial position sensing. Key features include very high transimpedance gain (up to 10^8 V/A typical), bandwidth up to several hundred kHz at moderate gain, low dark current due to on-chip FET input, and a wide dynamic range achievable through trade-offs between responsivity, bandwidth, and SNR. The uncommitted input and feedback pins allow designers to choose feedback resistor values for optimized noise-bandwidth trade-offs and to add filtering stages for specific applications. The OPT211's architecture pairs a diffused silicon photodiode with a precision FET-input op-amp transimpedance topology. Because the photodiode and amplifier share the same die, parasitic capacitance and leakage are minimized compared to discrete implementations, improving noise performance at high gain. The exposed feedback node allows external compensation, gain setting, or T-network feedback for very high effective transimpedance. Typical applications include precision photometry, optical position encoders, laser power measurement, smoke detectors, barcode scanners, spectrophotometers, and medical analytical instruments. It is well suited for low-light-level detection where the integrated front-end reduces PCB complexity and stray noise pickup. When designing with the OPT211, pay close attention to PCB layout: keep feedback components close to the feedback pin, use a guard ring around the input traces, and provide proper supply bypassing (0.1 uF ceramic in parallel with a larger tantalum or ceramic). Note that the OPT211 is a legacy Burr-Brown part now owned by Texas Instruments; long-term availability should be verified before new designs.