ADPD188BI Ambient light suppression

Hi Evgeny,

A strong ambient light causes the signals to go up as more photodiode current is generated. Even though there is ambient light rejection due to the use of short LED pulses and bandpass filter, it's impossible to block the whole ambient current especially when the ambient light source is strong. That's why there is a spec called ambient light headroom which indicates how much ambient photodiode current ADPD188BI can handle without saturation. You can also measure the ambient current with either float mode or TIA ADC mode. 

Generally speaking, the way to reduce the ambient current is a clever mechanical design, which would depend highly on the application. For example, if this is a smoke detector application, you can use a chamber. Also, keeping the integration window short helps. 

Regards,

Yigit

Hi Evgeny,

A strong ambient light causes the signals to go up as more photodiode current is generated. Even though there is ambient light rejection due to the use of short LED pulses and bandpass filter, it's impossible to block the whole ambient current especially when the ambient light source is strong. That's why there is a spec called ambient light headroom which indicates how much ambient photodiode current ADPD188BI can handle without saturation. You can also measure the ambient current with either float mode or TIA ADC mode. 

Generally speaking, the way to reduce the ambient current is a clever mechanical design, which would depend highly on the application. For example, if this is a smoke detector application, you can use a chamber. Also, keeping the integration window short helps. 

Regards,

Yigit