Data sheet
	
		
			
				
					
						Physical
					
				
				
					 
				
			
			
				
					Case/Package
				
				
					SOIC
				
			
			
				
					Mount
				
				
					Surface Mount
				
			
			
				
					Number
  of Pins
				
				
					24
				
			
			
				
					
						Technical
					
				
				
					 
				
			
			
				
					Conversion
  Rate
				
				
					15 kS/s
				
			
			
				
					Dual
  Supply Voltage
				
				
					5
  V
				
			
			
				
					Interface
				
				
					SPI , Serial
				
			
			
				
					Max
  Dual Supply Voltage
				
				
					5.25 V
				
			
			
				
					Max
  Operating Temperature
				
				
					85
  °C
				
			
			
				
					
				
				
					
				
			
			
				
					Min
  Dual Supply Voltage
				
				
					4.75 V
				
			
			
				
					Min
  Operating Temperature
				
				
					-40 °C
				
			
			
				
					Number
  of A/D Converters
				
				
					1
				
			
			
				
					Number
  of Analog Inputs
				
				
					1
				
			
			
				
					Number
  of Bits
				
				
					20
				
			
			
				
					Number
  of Channels
				
				
					1
				
			
			
				
					Number
  of Converters
				
				
					1
				
			
			
				
					Number
  of Elements
				
				
					1
				
			
			
				
					Polarity
				
				
					Bipolar , Unipolar
				
			
			
				
					Resolution
				
				
					20
  b
				
			
			
				
					Sampling
  Rate
				
				
					15 kS/s
				
			
			
				
					Supply
  Type
				
				
					Dual , Analog , Digital
				
			
			
				
					
						Compliance
					
				
				
					 
				
			
			
				
					Lead
  Free
				
				
					Lead Free
				
			
			
				
					Radiation
  Hardening
				
				
					No
				
			
			
				
					RoHS
				
				
					Compliant
				
			
		
	
	20-BIT ANALOG-TO-DIGITAL CONVERTER
	The DDC101 is a precision, wide dynamic range, charge digitizing A/D converter with 20-bit resolution. Lowlevel current output devices, such as photosensors, can bedirectly connected to its input. The most stringent accuracy requirements of many unipolar output sensor applications occur at low signal levels. To meet this requirement, Burr-Brown developed the adaptive delta odulation
architecture of the DDC101 to provide linearly improving noise and linearity errors as the input signal level decreases. The DDC101 combines the functions of current-to-voltage conversion, integration, input programmable gain amplification, A/D conversion, and digital filtering to produce precision, wide dynamic range results. The input signal can be a low level current connected directly into the unit or a voltage connected through a user selected resistor. Although the DDC101 is optimized for unipolar signals, it can also accurately digitize bipolar input signals. The patented delta modulation topology combines charge integration and digitization
functions. Oversampling and digital filtering reduce system noise dramatically. Correlated Double Sampling (CDS) captures and eliminates steady state and conversion cycle dependent offset and switching errors that are not eliminated with conventional analog circuits. The DDC101 block diagram is shown below. During conversion, the input signal is collected on the Internal integration capacitance for a user determined integration period. A high precision, autozeroed comparator samples the analog input node. Tracking logic updates the internal high resolution D/A converter at a 2MHz rate to maintain the analog input at virtual ground. A user programmable digital filter oversamples the tracking logic’s output. The digital filter passes a low noise, high resolution digital output to the serial I/O register. The serial outputs of multiple DDC101 units can be easily connected together
in series or parallel if desired to minimize interconnections.