Silicon Imaging , Inc. 2004 Page 17 of 39 Company Confidential
The full formula for calculating the pixel integration time is:
T_INT = ((65536 x R Reg0x09) * Row_Clocks - P1 + 132 - Reg0x0C) * Clock_rate
Row_Clocks = Width + P1 +P2 +P3
P1
= Frame Start Blanking #1 (Row Binning)
331 if Reg0x22[5-4] = 0, normal
673 if Reg0x22[5-4] = 1, Bin 2x
999 if Reg0x22[5-4] = 2, Bin 3x
P2 = Frame Start Blanking #2 (Column Binning)
38 if Reg0x23[5-4] = 0, normal
22 if Reg0x23[5-4] = 1, Bin 2x
14 if Reg0x23[5-4] = 2, Bin 3x
P3 = Horizontal_Blanking set by Reg0x05 (min value = 21)
Note: P1 + P2 + P3 = 331 + 38 + 21 =
390
for min values and no binning
Flickerless Operation
While the user can adjust the integration time to the desired value according to the aforementioned formula, not all
integration times may be desired under certain lighting conditions. If the light source has a flicker component, then
the integration time needs to be set properly to avoid banding in the image. Under 60Hz flicker, the integration time
must be a multiple of 1/120 of a second to avoid flicker. Under 50Hz flicker, the integration time must be a multiple of
1/100 of a second to avoid flicker.
Short Exposure ( Less than 1 Row Time)
To set the SI-3300 to an integration time less than 1 row, the shutter width register 0x09 must first be set to 1.
Shorter integration times are controlled by the Shutter Delay register 0x0C.
T_INT = (Reg0x09 * Row_Clocks) - P1 + 132 - Reg0x0C * Clock_rate
For an image width of 2048, no binning, Reg9 set to 1, the sub-row short exposure time is calculated as follows:
T_INT
= (1 * Row_Clocks) – P1 + 132 - Reg0C
Row_Clocks = width + P1 +P2 +P3
= Width + 390
P1
= 331 (673 = Bin2x, 999, Bin 3x)
Reg0C
= 21 (minimum value)
T_INT
= Row_Clocks – 331 + 132 – Reg0x0C * clock_rate
= (Width + 390) – 199 – Reg0x0C * clock_rate
= Width + 191 – Reg0x0C * clock_rate
Width
(Reg4 + 1)
Row_cntr
(Width + 191)
Reg09
(1 Row)
Reg0C
(short exposure)
Exposure Clocks
Row_Cntr - Reg0c
Exposure_Time
20MHz (50ns)
Exposure_Time
40MHz (25ns)
2048
2239
x0001
x085b (2139)
100
5.0 usec
2.5 usec
2048
2239
x0001
x07f7 (2039)
200
10 usec
5.0 usec
2048
2239
x0001
x06cb (1739)
500
25 usec
12.5 usec
2048
2239
x0001
x04d7 (1239)
1000
50 usec
25 usec