WM8253: Single Channel CCD/CIS ADC


The WM8253 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 6MSPS. 

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 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 uses an analogue supply voltage of 3.3V and a digital interface supply of between 1.8V and 3.3V. The WM8253 typically only consumes 132mW when operating from a single 3.3V supply.


  • 16-bit ADC
  • 6MSPS conversion rate
  • Low power - 132mW typical
  • 3.3V single supply or 3.3V/1.8V dual supply operation 
  • Single channel operation
  • Correlated double sampling
  • Programmable gain (8-bit resolution) 
  • Programmable offset adjust (8-bit resolution)
  • Programmable clamp voltage
  • 4-bit wide multiplexed data output format
  • Internally generated voltage references 
  • 20-lead SSOP package
  • Serial control interface