Datasheet AD7691 (Analog Devices) - 9

AD7691 Data Sheet PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REF 1 10 VIO VDD 2 9 SDI AD7691 IN+ 3 8 SCK TOP VIEW REF 1 10 VIO IN– 4 (Not to Scale) 7 SDO VDD 2 9 SDI AD7691 GND 5 6 CNV IN+ 3 8 SCK TOP VIEW NOTES IN– 4 (Not to Scale) 7 SDO 1. THE EXPOSED PAD IS NOT CONNECTED
004 5
GND INTERNALLY. FOR INCREASED RELIABILITY OF
00
5 6 CNV
6- 6-
THE SOLDER JOINTS, IT IS RECOMMENDED THAT
614 0 14
THE PAD BE SOLDERED TO THE GROUND PLANE.
06 Figure 5. 10-Lead MSOP Pin Configuration Figure 6. 10-Lead LFCSP Pin Configuration
Table 8. Pin Function Descriptions Pin No. Mnemonic Type1 Description
1 REF AI Reference Input Voltage. The REF range is from 0.5 V to VDD. It 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 Differential Positive Analog Input. Referenced to IN−. The input range for IN+ is between 0 V and VREF, centered about VREF/2 and must be driven 180° out of phase with IN−. 4 IN− AI Differential Negative Analog Input. Referenced to IN+. The input range for IN− is between 0 V and VREF, centered about VREF/2 and must be driven 180° out of phase with IN+. 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 of the part, either chain or CS mode. 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 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, 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 Exposed Pad. The exposed pad is not connected internally. For increased reliability of the solder joints, it is recommended that the pad be soldered to the ground plane. 1AI = analog input, DI = digital input, DO = digital output, and P = power. Rev. E | Page 8 of 28 Document Outline FEATURES APPLICATIONS APPLICATION DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS Thermal Resistance 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 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 APPLICATION HINTS LAYOUT EVALUATING THE AD7691 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE