Datasheet AD7984 (Analog Devices) - 8

Data Sheet AD7984 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REF 1 10 VIO VDD 2 9 SDI AD7984 IN+ 3 8 SCK REF 1 10 VIO (EXPOSED VDD PAD)* 2 9 SDI AD7984 IN– 4 7 SDO IN+ 3 8 SCK TOP VIEW GND 5 6 CNV IN– (Not to Scale) 4 7 SDO
4 00
GND 5 6 CNV
3- -005 97
*EXPOSED PADDLE CAN BE CONNECTED
06
TO GROUND.
06973 Figure 4. 10-Lead MSOP Pin Configuration Figure 5. 10-Lead LFCSP Pin Configuration
Table 6. Pin Function Descriptions Pin No. Mnemonic Type1 Description
1 REF AI Reference Input Voltage. The REF range is 2.9 V to 5.1 V. This pin is referred to the GND pin and should be decoupled closely to the GND pin with a 10 μF capacitor. 2 VDD P Power Supply. 3 IN+ AI Differential Positive Analog Input. 4 IN− AI Differential Negative Analog Input. 5 GND P Power Supply Ground. 6 CNV DI Convert Input. This input has multiple functions. On its rising edge, it initiates the conversions and selects the interface mode of the part: chain mode or CS mode. In CS mode, the SDO pin is enabled when CNV is low. In chain mode, the data should be read when CNV is high. 7 SDO DO Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK. 8 SCK DI Serial Data Clock Input. When the part is selected, the conversion result is shifted out by this clock. 9 SDI DI Serial Data Input. This input provides multiple features. It selects the interface mode of the ADC as follows: Chain mode is selected if SDI is low during the CNV rising edge. In this mode, SDI is used as a data input to daisy-chain the conversion results of two or more ADCs onto a single SDO line. The digital data level on SDI is output on SDO with a delay of 18 SCK cycles. CS mode is selected if SDI is high during the CNV rising edge. In this mode, either SDI or CNV can enable the serial output signals when low. If SDI or CNV is low when the conversion is complete, the busy indicator feature is enabled. 10 VIO P Input/Output Interface Digital Power. Nominally at the same supply as the host interface (1.8 V, 2.5 V, 3 V, or 5 V). 1 AI = analog input, DI = digital input, DO = digital output, and P = power. Rev. B | Page 7 of 24 Document Outline FEATURES APPLICATIONS APPLICATION DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY THEORY OF OPERATION CIRCUIT INFORMATION CONVERTER OPERATION Transfer Functions TYPICAL CONNECTION DIAGRAM ANALOG INPUTS DRIVER AMPLIFIER CHOICE SINGLE-TO-DIFFERENTIAL DRIVER VOLTAGE REFERENCE INPUT POWER SUPPLY DIGITAL INTERFACE MODE, 3-CS WIRE WITHOUT BUSY INDICATOR CS MODE, 3-WIRE WITH BUSY INDICATOR CS MODE, 4-WIRE WITHOUT BUSY INDICATOR CS MODE, 4-WIRE WITH BUSY INDICATOR CHAIN MODE WITHOUT BUSY INDICATOR CHAIN MODE WITH BUSY INDICATOR APPLICATION HINTS LAYOUT EVALUATING THE AD7984 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE