Datasheet AD7687 (Analog Devices) - 10

Data Sheet AD7687 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REF 1 10 VIO REF 1 10 VIO VDD 2 9 SDI AD7687 VDD 2 9 SDI IN+ AD7687 3 8 SCK TOP VIEW IN+ 3 TOP VIEW 8 SCK IN– 4 (Not to Scale) 7 SDO (Not to Scale) IN– 4 7 SDO GND 5 6 CNV
02972-005
GND 5 6 CNV
6
NOTES
00 2-
1. FOR THE LFCSP ONLY, THE EXPOSED
97
PADDLE MUST BE CONNECTED TO GND.
02 Figure 4. 10-Lead MSOP Pin Configuration Figure 5. 10-Lead LFCSP Pin Configuration
Table 8. Pin Function Descriptions Pin No. Mnemonic Type1 Function
1 REF AI Reference Input Voltage. The REF range is from 0.5 V to VDD, referred to the GND pin. Place a 10 μF decoupling capacitor as close to the pin as possible. 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 leading edge, it initiates a conversion and selects the interface mode: chain or CS (depending on the state of SDI). In CS mode, CNV enables the SDO pin when low. In chain mode, the data is read while CNV is high. 7 SDO DO Serial Data Output. The conversion result is output on this pin. It is synchronized to SCK. SDO also acts as the BUSY indicator if the feature is enabled. 8 SCK DI Serial Data Clock Input. This input primarily shifts data out on SDO when data is valid. In chain mode, the state of SCK determines if the BUSY indicator feature is enabled. If SCK is low during the CNV rising edge, the BUSY feature is disabled. If it is high during the CNV rising edge, the BUSY feature is enabled. 9 SDI DI Serial Data Input. This input serves multiple functions. 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 16 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, and 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). EPAD N/A For the LFCSP only, the exposed paddle must be connected to GND. 1AI means analog input, DI means digital input, DO means digital output, P means power, and N/A means not applicable. Rev. E | Page 9 of 26 Document Outline FEATURES APPLICATIONS TYPICAL APPLICATION CIRCUIT GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS Timing Diagrams ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TERMINOLOGY TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION CIRCUIT INFORMATION CONVERTER OPERATION Transfer Functions TYPICAL CONNECTION DIAGRAM ANALOG INPUT DRIVER AMPLIFIER CHOICE SINGLE-TO-DIFFERENTIAL DRIVER VOLTAGE REFERENCE INPUT POWER SUPPLY SUPPLYING THE ADC FROM THE REFERENCE DIGITAL INTERFACE CS\ MODE, 3-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 APPLICATIONS INFORMATION LAYOUT EVALUATING THE PERFORMANCE OF THE AD7687 OUTLINE DIMENSIONS ORDERING GUIDE