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Maximum values for HighGain, LowGain and Combined modes for MityCAM-CIS1910

Added by Anton Bakulev almost 3 years ago

I tested maximum values in images acquired from MityCAM-CIS1910 and got that
for HighGain and LowGain there is 2047
for Combined mode there is 61380

2047 is 11111111111 (11bits)
61380 is 1110111111000100 (16bits)

According to CIS1910 specification it should be 12bit values in HighGain and LowGain modes and full 16bits in Combined mode.
Why there is so strange values in MityCam ?


Replies (1)

RE: Maximum values for HighGain, LowGain and Combined modes for MityCAM-CIS1910 - Added by Michael Williamson almost 3 years ago

I do not see a specification for the ADC converters to be 12 bit, only 11 bit. Can you please provide me a reference spec version and paragraph that indicates 12 bits?

There is a DOUT [ 11 ] pin, but that is only a flag that indicates a multiplexor value (the high gain data output can be used to multiplex high gain outputs and low gain outputs based on the the ADC value in the high gain channel, see section "2.3 Sensor Data"). Is this what you are looking at for 12 bits? The ADCs are only 11 bits.

With 2047 maximum values, the theoretical maximum combined value is:

2047+30*2047 = 63457.

However, full well is actually a little lower than the maximum ADC count in the low gain channel and is also sensitivy to the VTX2_NEG voltage level (which controls anti-blooming), so you may not reach all the way up to that level.

At a 1.7 DN/e- spec'd level with >= 33000 e- of full well spec, you may see a maximum combined count that is closer to ~55,000 counts on various pixels (that is the maximum low gain value at x1 setting will be 0.055 * 33000, or 1815 maximum value unscaled instead of 2047).

-Mike

-Mike

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