Hi there. I am looking at using a LTR-329ALS-01 as a high speed detector for counting the pulses of an LED but i cant find the rise and fall times for the device. I need to know that i am going to get a clean high/low logic trigger as the pulses are going to be fast in some case’s, up-to 12ps. Can you help???
Hello @spark-doctor,
The LTR-329ALS-01 is a surface mount ambient light detector:
- response similar to human eye
- analog output proportional to light intensity
- I2C interface
The speed at which data may be pulled from the device is dependent on the I2C clock. With 16 bits this is not trivial. It is also dependent on the “integration time” and the “measurement rate.” By default, this is a 100 ms sensor.
This is very very slow compared to your 12 ps specification.
Let me do some more research to see if we can find something faster. In the interim, could you tell us more about your product?
Best wishes,
APDahlen
Hello @spark-doctor,
As I suspected, the response of an ALS appears to be a function of the physics package itself. A typical device such as the APDS-9008-020 has a 5 ms rise time in response to a moderately bright light. There are also question of noise which could impact measurement. This is likely the reason datasheets talk about integration.
Recommend an alternative technology such as Photodiodes.
Please let us know more about your application including wavelength requirements so that we may better assist.
Best wishes,
APDahlen
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Hi and thanks for the information. Sorry, i cant discuss the project in a open forum but if you can email me, i should be able to give you more details. Ian
No worries, @spark-doctor,
You can message me by clicking on my avatar icon to the left of this note.
However, I would ask that you be a public as possible. There are truly talented people reading these posts. I appreciate when they challenge my work and identify alternative solutions.
Sincerely,
Aaron