Microchip Technology MCP6031DM-PTPLS User Manual

DS51763A-page 6

© 2008 Microchip Technology Inc.

The MCP6031 Photodiode PICtail™ Plus Demo Board demonstrates how to use a 
transimpedance amplifier, which consists of MCP6031 high precision op amp and 
external resistors, to convert photo-current (I

S

) to voltage. The circuit was not calibrated 

for absolute accuracy.

The RC low-pass filter that is implemented in this circuit can remove the high frequency 
noise and interference from the signal path prior to the analog-to-digital (A/D) 
conversion.

The PICmicro

®

 on the Explorer 16 Development Board communicates with the 

MCP6031 Photodiode PICtail™ Plus Demo Board and completes the analog-to-digital 
conversion. 

The measured voltage (V

OUT

) and calculated illuminance (L) will be shown on LCD 

screen on board. The illuminance (L) will be calculated by the equation:

Figure 1-2 shows the block diagram of the MCP6031 Photodiode PICtail™ Plus Demo 
Board .

 

For high measurement accuracy, an external stand-alone ADC with higher 
resolution needs to be used.

⁄

(

) 10000 l

μ

(

)

RC Low-Pass 
Filter  

 10 Bit ADC Module               V

REF

 = 3.3V

LCD Screen

V

DD

 = V

REF

Vout = ___________ V
L = ____________ lx

V

OUT

I

S

       = 3.3V