link to page 17 AD7940PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONSSOT-23MSOPV8CSV6CSDD1DD1AD7490GND7SDATAGNDAD7940225SDATATOP VIEWTOP VIEWGND6NCV34SCLKIN3(Not to Scale)(Not to Scale)V5SCLK 03305-0-023 IN4 Figure 3. SOT-23 Pin Configuration NC = NO CONNECT 03305-0-003 Figure 4. MSOP Pin Configuration Table 5. Pin Function Descriptions Pin No.Pin No.SOT-23MSOPMnemonic Function 1 1 V range for the AD7940 is from 2.5 V to 5.5 V. DD Power Supply Input. The VDD 2 2, 3 GND Analog Ground. Ground reference point for all circuitry on the AD7940. All analog input signals should be referred to this GND voltage. 3 4 V Analog Input. Single-ended analog input channel. The input range is 0 V to V . IN DD 4 5 SCLK Serial Clock. Logic input. SCLK provides the serial clock for accessing data from this part. This clock input is also used as the clock source for the AD7940's conversion process. 5 7 SDATA Data Out. Logic output. The conversion result from the AD7940 is provided on this output as a serial data stream. The bits are clocked out on the falling edge of the SCLK input. The data stream from the AD7940 consists of two leading zeros followed by 14 bits of conversion data that are provided MSB first. This will be followed by four trailing zeroes if CS is held low for a total of 24 SCLK cycles. See the Serial Interface section. 6 8 CS Chip Select. Active low logic input. This input provides the dual function of initiating conversions on the AD7940 and framing the serial data transfer. N/A 6 NC No Connect. This pin should be left unconnected. Rev. A | Page 7 of 20 Document Outline Table of Contents Specifications1F Timing Specifications Absolute Maximum Ratings ESD Caution Pin Configurations and Function Descriptions Terminology Typical Performance Characteristics Circuit Information Converter Operation Analog Input ADC Transfer Function Typical Connection Diagram Digital Inputs Modes of Operation Normal Mode Power-Down Mode Power vs. Throughput Rate Serial Interface Microprocessor Interfacing AD7940 to TMS320C541 AD7940 to ADSP-218x AD7940 to DSP563xx Application Hints Grounding and Layout Evaluating the AD7940 Performance Outline Dimensions Ordering Guide