Datasheet AD7946 (Analog Devices) - 8

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Data Sheet AD7946 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REF 1 10 VIO REF 1 10 VIO VDD 2 9 SDI AD7946 VDD 2 9 SDI IN+ 3 8 SCK AD7946 TOP VIEW IN+ 3 TOP VIEW 8 SCK IN– 4 (Not to Scale) 7 SDO (Not to Scale)
004
IN– 4 7 SDO GND 5 6 CNV 5 6
04656-
GND CNV NOTES
Figure 4. 10-Lead MSOP Pin Configuration
1. EXPOSED PAD. THE EXPOSED PAD MUST BE CONNECTED TO GROUND. THIS
005
CONNECTION IS NOT REQUIRED TO MEET ELECTRICAL PERFORMANCES.
04656- 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 from 0.5 V to VDD, and is referred to the GND pin. This pin should be decoupled closely to the pin with a 10 µF capacitor. 2 VDD P Power Supply. 3 IN+ AI Analog Input. It is referred to IN−. The voltage range, that is, the difference between IN+ and IN−, is 0 V to REF. 4 IN− AI Analog Input Ground Sense. Connect to the analog ground plane or to a remote sense ground. 5 GND P Power Supply Ground. 6 CNV DI Convert Input. This input has multiple functions. On its leading edge, it initiates the conversions and selects the interface mode, chain, or CS. In CS mode, it enables the SDO pin when 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 14 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 Exposed Pad. The exposed pad must be connected to ground. This connection is not required to meet electrical performances. 1 AI = analog input, DI = digital input, DO = digital output, and P = power. Rev. B | Page 7 of 24 Document Outline Features Applications Typical Application Circuit 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 Input Driver Amplifier Choice Voltage Reference Input Power Supply Supplying the ADC from the Reference Single-Supply Application Digital Interface CS/ MODE 3-Wire, No BUSY Indicator CS/ Mode 3-Wire with BUSY Indicator CS/ Mode 4-Wire, No BUSY Indicator CS/ Mode 4-Wire with BUSY Indicator Chain Mode, No BUSY Indicator Chain Mode with BUSY Indicator Application Guidelines Layout Evaluating the Performance of the AD7946 Outline Dimensions Ordering Guide