WM8255

w WM8255 Single Channel 16-bit CIS/CCD AFE with RGB LED Current Drive DESCRIPTION The WM8255 is a 16-bit analogue front end/digitiser IC which processes and digitises the analogue output signals from CCD sensors or Contact Image Sensors (CIS) at pixel sample rates of up to 12 MSPS. The device includes a complete signal processing channel containing Reset Level Clamping, Correlated Double Sampling, Programmable Gain and Offset adjust functions. Internal multiplexers allow fast switching of offset and gain for line-by-line colour processing. The output from this channel is time multiplexed into a high-speed 16-bit Analogue to Digital Converter. The digital output data is available in a 2 bit or 4-bit wide multiplexed format. An internal 4-bit DAC is supplied for internal reference level generation. This may be used during CDS to reference CIS signals or during Reset Level Clamping to clamp CCD signals. An external reference level may also be supplied. ADC references are generated internally, ensuring optimum performance from the device. The device includes an RGB LED current drive using current and PWM functionality to control the operation of sensor LEDs. The device typically uses an analogue supply voltage of 5.75V and a digital interface supply of 3.3V. BLOCK DIAGRAM FEATURES  16-bit ADC  12 MSPS conversion rate  Low power – 250 mW typical  5.75V and 3.3V supply operation  Single channel operation  Correlated double sampling  Programmable gain (8-bit resolution) ...