AK8448 Datasheet, PDF (43/53 Pages) Asahi Kasei Microsystems – 6-Channel Linear Sensor compatible 10 Bit 40 MSPS x 3 Analog Pre-Processor

ASAHI KASEI
[AK8448]
„ Signal Polarity
The AK8448 accepts both positive and negative input polarities.
Either signal polarity is selected by setting Signal Polarity register ( R0,D5 ) to meet
sensor types to be used.
In general, CCD exhibits negative polarity characteristics and CIS exhibits positive
polarity characteristics. Either polarity can be selected, regardless of sensor I/F mode
setting.
z Negative polarity characteristics
Reference Level
Black (ADC code 000h
Data Level
z Positive polarity characteristics
Data Level
White (ADC code 3FFh
White (ADC code 3FFh
Reference Level
Figure 9 Signal Polarities
Black (ADC code 000h
„ Output Data Control
ADC output data is output in either 5 Bit-wide or 10 Bit-wide by setting Data Width
register ( R1, D3 ).
When 5 Bit-wide data mode is selected, data is output on each of three 5 Bit buses –
DA4 ~ DA0, DB4 ~ DB0 and DC4 ~ DC0 respectively which correspond to each ADC.
When 10 Bit-wide data mode is selected, data is output on 10 pins – DA4 ( MSB ) ~ DA0
and DB4 ~ DB0 ( LSB ).
In 5 Bit-wide data mode, the upper 5 Bit of data is output at the rising edge of ADCK, and
the lower 5 Bit at the falling edge of ADCK.
In 10 Bit-wide data mode, two different channel data are output at the rising edge and at
the falling edge of ADCK respectively.
It is also possible to output data at only the falling edge of ADCK in 10 Bit-wide data
mode, by setting ADCK Frequency register ( R0, D1 ).
In this operation, it is required to input ADCK at the frequency of a total sum of pixel rate
of all channels ( total pixel rate ). Un-used buses DB4 ~ DB0 and DC4 ~ DC0 such as a
case in 1 channel mode with 5 Bit-wide output, will output Low levels.
MS1513-E-00
43
2013/02