rosette
Newbie level 1
proximity like a led
Hi all,
I'm designing a device with a pwm-modulated rgb led module and need to measure ambient illuminance (from the environment) with a sensor mounted in close proximity. I'd like to use the same sensor to monitor led output, so I can't just rearrange things so that light from the led doesn't reach the sensor.
One obvious way to go, because the led is driven by a pwm signal, is to only measure light during the off periods. Thus, a photosensor + driver that behaves like a pixel with an electronic shutter and integration control would be very nice. Does anyone know of such a device (photo ic or driver ic)?
I've been using a hamamatsu s9706 for prototyping which has a digital control for integration. This is almost what I'm looking for, except that enabling integration automatically zeros the integration result, so the integration time cannot be split into multiple "slices." In order to get a good reading I need integration times longer than a couple of milliseconds, which is too long to keep the leds turned off...
Anyone know of any amplifier/sensor+amplifier modules with something equivalent to an electronic shutter?
Maybe I'm making the problem too hard and should just use a fast amplifier with enough gain to produce a good signal, and measure during the off periods..[/GVideo]
Hi all,
I'm designing a device with a pwm-modulated rgb led module and need to measure ambient illuminance (from the environment) with a sensor mounted in close proximity. I'd like to use the same sensor to monitor led output, so I can't just rearrange things so that light from the led doesn't reach the sensor.
One obvious way to go, because the led is driven by a pwm signal, is to only measure light during the off periods. Thus, a photosensor + driver that behaves like a pixel with an electronic shutter and integration control would be very nice. Does anyone know of such a device (photo ic or driver ic)?
I've been using a hamamatsu s9706 for prototyping which has a digital control for integration. This is almost what I'm looking for, except that enabling integration automatically zeros the integration result, so the integration time cannot be split into multiple "slices." In order to get a good reading I need integration times longer than a couple of milliseconds, which is too long to keep the leds turned off...
Anyone know of any amplifier/sensor+amplifier modules with something equivalent to an electronic shutter?
Maybe I'm making the problem too hard and should just use a fast amplifier with enough gain to produce a good signal, and measure during the off periods..[/GVideo]