LTC2440 FUNCTIONAL BLOCK DIAGRAM INTERNAL VCC OSCILLATOR GND AUTOCALIBRATION AND CONTROL fO (INT/EXT) IN+ + IN– – SDO ADC SCK SERIAL CS DECIMATING FIR INTERFACE SDI BUSY DAC 2440 F01 EXT + – REF+ REF– Figure 1. Functional Block DiagramTEST CIRCUITS VCC 1.69k SDO SDO 1.69k CLOAD = 20pF CLOAD = 20pF Hi-Z TO VOH VOL TO VOH V Hi-Z TO VOL 2440 TA03 OH TO Hi-Z VOH TO VOL V 2440 TA04 OL TO Hi-Z APPLICATIONS INFORMATION CONVERTER OPERATION CONVERT Converter Operation Cycle The LTC2440 is a high speed, delta-sigma analog-to-digital SLEEP converter with an easy to use 4-wire serial interface (see Figure 1). Its operation is made up of three states. The converter operating cycle begins with the conversion, followed by the low power sleep state and ends with the FALSE CS = LOW AND data output (see Figure 2). The 4-wire interface consists SCK of serial data input (SDI), serial data output (SDO), serial TRUE clock (SCK) and chip select (CS). The interface, timing, DATA OUTPUT operation cycle and data out format is compatible with 2440 F02 the LTC2410. Figure 2. LTC2440 State Transition Diagram 2440fe For more information www.linear.com/LTC2440 9 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Typical Performance Characteristics Pin Functions Typical Application Related Parts