LTC2485 24-Bit ∆Σ ADC with Easy Drive Input Current Cancellation and I2C Interface FeaTuresDescripTion n Easy Drive™ Technology Enables Rail-to-Rail Inputs The LTC®2485 combines a 24-bit plus sign No Latency with Zero Differential Input Current ∆Σ™ analog-to-digital converter with patented Easy Drive n Directly Digitizes High Impedance Sensors with technology and I2C digital interface. The patented sampling Full Accuracy scheme eliminates dynamic input current errors and the n GND to VCC Input/Reference Common Mode Range shortcomings of on-chip buffering through automatic n 2-Wire I2C Interface cancellation of differential input current. This allows large n Programmable 50Hz, 60Hz or Simultaneous external source impedances and input signals, with rail-to- 50Hz/60Hz Rejection Mode rail input range to be directly digitized while maintaining n 2ppm (0.25LSB) INL, No Missing Codes exceptional DC accuracy. n 1ppm Offset and 15ppm Full-Scale Error The LTC2485 includes an on-chip oscillator. The LTC2485 n Selectable 2x Speed Mode can be configured through an I2C interface to reject line n No Latency: Digital Filter Settles in a Single Cycle frequencies. 50Hz, 60Hz or simultaneous 50Hz/60Hz n Single Supply 2.7V to 5.5V Operation line frequency rejection can be selected as well as a 2x n Internal Oscillator speed-up mode. n Six Addresses Available and One Global Address for Synchronization The LTC2485 allows a wide common mode input range n Available in a Tiny (3mm (0V to V × 3mm) CC) independent of the reference voltage. The 10-Lead DFN Package reference can be as low as 100mV or can be tied directly to VCC. The LTC2485 includes an on-chip trimmed oscil- applicaTions lator eliminating the need for external crystals or oscil- n lators. Absolute accuracy and low drift are automatically Direct Sensor Digitizer n maintained through continuous, transparent, offset and Weight Scales n full-scale calibration. Direct Temperature Measurement L n , LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Strain Gauge Transducers No Latency ∆∑ and Easy Drive are trademarks of Linear Technology Corporation. All other n trademarks are the property of their respective owners. Instrumentation n Industrial Process Control n DVMs and Meters Typical applicaTion+FS Error vs RSOURCE at IN+ and IN– 80 VCC = 5V VCC 60 VREF = 5V V + IN = 3.75V V – = 1.25V 0.1µF 1µF 40 IN fO = GND 20 TA = 25°C 10k SCL I C DIFF = 0 REF+ VCC 2-WIRE IN = 1µF V + IN SDA I2C INTERFACE 0 SENSE LTC2485 CA0/f0 –20 +FS ERROR (ppm) V – 6 ADDRESSES IN CA1 –40 10k GND REF– 2485 TA01a 0.1µF –60 –80 1 10 100 1k 10k 100k RSOURCE (Ω) 2485 TA01b 2485fd For more information www.linear.com/LTC2485 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics (Normal Speed) Electrical Characteristics (2x Speed) Converter Characteristics Analog Input and Reference I2C Digital Inputs and Digital Outputs Power Requirements Timing Characteristics I2C Timing Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Applications Information Package Description Revision History Typical Application Related Parts
