cube007
Full Member level 6
Hello,
For explaining my problem I give you an example of the application:
Situation: Let’s say there are three light sources (red, green and blue). These can be modulated with an analog signal. All of these have a different reaction time (different delay from the input signal).
The analog input signals from the light sources are modulated with a DAC, so three DACs are needed (in the future there will be more colors: cyan, magenta, yellow). The output off all three light sources should be at the same time. So the input signal must have a different timing (adapted to the color). That means that each DACs needs a different LDAC (load DAC) signal which must be adjusted for the light sources.
Requirements: The analog signal can be modulated up to 200 kHz (5 us). The reaction time differs from 0 to 50 us. The DACs should be in the same package for a small board layout.
Here are some possibilities to solve the problem.
1. Using a separated DAC for each color (too many devices)
2. Using a multiple DAC with different LDAC signals (I haven’t found such devices with the desired sample rate)
3. Designing an analog circuit to put this between the DAC and the color input.
Another possibility is to use a multiple DAC with one LDAC (there are a lot of on the market). To achieve different output timings the controller has to update the internal DAC registers for the colors at different time. When one register was updated the controller asserts the LDAC which will update all output registers but only one registers is changing (so only the desired analog signal is changing). That means that the controller has to update the registers faster than in normal operation. Does the DAC also need a faster settling time when updating the output registers “asynchronously”?
What do you think about this problem? I hope it is clear what I want. Explaining something in a foreign language is not easy.
Bye,
cube007
For explaining my problem I give you an example of the application:
Situation: Let’s say there are three light sources (red, green and blue). These can be modulated with an analog signal. All of these have a different reaction time (different delay from the input signal).
The analog input signals from the light sources are modulated with a DAC, so three DACs are needed (in the future there will be more colors: cyan, magenta, yellow). The output off all three light sources should be at the same time. So the input signal must have a different timing (adapted to the color). That means that each DACs needs a different LDAC (load DAC) signal which must be adjusted for the light sources.
Requirements: The analog signal can be modulated up to 200 kHz (5 us). The reaction time differs from 0 to 50 us. The DACs should be in the same package for a small board layout.
Here are some possibilities to solve the problem.
1. Using a separated DAC for each color (too many devices)
2. Using a multiple DAC with different LDAC signals (I haven’t found such devices with the desired sample rate)
3. Designing an analog circuit to put this between the DAC and the color input.
Another possibility is to use a multiple DAC with one LDAC (there are a lot of on the market). To achieve different output timings the controller has to update the internal DAC registers for the colors at different time. When one register was updated the controller asserts the LDAC which will update all output registers but only one registers is changing (so only the desired analog signal is changing). That means that the controller has to update the registers faster than in normal operation. Does the DAC also need a faster settling time when updating the output registers “asynchronously”?
What do you think about this problem? I hope it is clear what I want. Explaining something in a foreign language is not easy.
Bye,
cube007