The Photodiode Light Detector Demo Board showcases how to use a transimpedance amplifier U1 (MCP6021) and external resistors, to convert photocurrent (IP) from a photodiode to an output voltage.
This board has two different circuit implementations, photovoltaic and photoconductive mode.
In the photoconductive topology, the photodetector needs to be reverse biased. Amplifier U2 provides a reverse bias of VDD/2 to the photodetector, where the photodetector's anode is the circuit GND.
In the photovoltaic topology, Amplifier U2 generates a reference voltage of VDD/2 so, that the circuit provides an output that is referenced to VDD/2 and allows an Analog-to-Digital Converter (ADC) to sample the signal with reference to the circuit GND.
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Using MCP6491 Op Amps for Photodetection Applications | 09 May 2013 | Link | Application Notes |
Amplifying High-Impedence Sensors ? Photodiode Example | 25 Jul 2006 | Link | Application Notes |
Product |
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Product |
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MCP6021 | Rail-to-Rail Input/Output, 10 MHz Op Amps | MCP6021 | Rail-to-Rail Input/Output, 10 MHz Op Amps |
MCP6491 | 7.5 MHz, Low-Input Bias Current Op Amps | MCP6491 | 7.5 MHz, Low-Input Bias Current Op Amps |
MCP6031 | 0.9 µA, High-Precision Op Amps | MCP6031 | 0.9 µA, High-Precision Op Amps |