Datasheet AD7890 (Analog Devices) - 9

AD7890 Pin No. Mnemonic Description
14 SHA IN Track/Hold Input. The input to the on-chip track/hold is applied to this pin. It is a high impedance input and the input voltage range is 0 V to 2.5 V. 15 AGND Analog Ground. Ground reference for track/hold, comparator, and DAC. 16 VIN1 Analog Input Channel 1. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 17 VIN2 Analog Input Channel 2. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 18 VIN3 Analog Input Channel 3. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 19 VIN4 Analog Input Channel 4. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 20 VIN5 Analog Input Channel 5. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 21 VIN6 Analog Input Channel 6. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 22 VIN7 Analog Input Channel 7. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 23 VIN8 Analog Input Channel 8. Single-ended analog input. The analog input range on is ±10 V (AD7890-10), 0 V to 4.096 V (AD7890-4) and 0 V to 2.5 V (AD7890-2). The channel to be converted is selected using the A0, A1, and A2 bits in the control register. The multiplexer has guaranteed break-before-make operation. 24 REF OUT/REF IN Voltage Reference Output/Input. The part can be used with either its own internal reference or with an external reference source. The on-chip 2.5 V reference voltage is provided at this pin. When using this internal reference as the reference source for the part, REF OUT should decoupled to AGND with a 0.1 μF disc ceramic capacitor. The output impedance of this reference source is typically 2 kΩ. When using an external reference source as the reference voltage for the part, the reference source should be connected to this pin. This overdrives the internal reference and provides the reference source for the part. The REF IN input is buffered on-chip. The nominal reference voltage for correct operation of the AD7890 is 2.5 V. Rev. C | Page 8 of 28 Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TERMINOLOGY CONTROL REGISTER THEORY OF OPERATION CONVERTER DETAILS CIRCUIT DESCRIPTION AD7890-10 Analog Input AD7890-4 Analog Input AD7890-2 Analog Input TRACK/HOLD AMPLIFIER REFERENCE TIMING AND CONTROL CEXT FUNCTIONING SERIAL INTERFACE SELF-CLOCKING MODE Write Operation EXTERNAL CLOCKING MODE Read Operation Write Operation SIMPLIFYING THE INTERFACE MICROPROCESSOR/MICROCONTROLLER INTERFACE AD7890 TO 8051 INTERFACE AD7890 TO 68HC11 INTERFACE AD7890 TO ADSP-2101 INTERFACE AD7890 TO DSP56000 INTERFACE AD7890 TO TMS320C25/30 INTERFACE ANTIALIASING FILTER PERFORMANCE LINEARITY NOISE DYNAMIC PERFORMANCE EFFECTIVE NUMBER OF BITS OUTLINE DIMENSIONS ORDERING GUIDE