Datasheet AD7890 (Analog Devices)

LC2MOS 8-Channel, 12-Bit Serial Data Acquisition System AD7890 FEATURES FUNCTIONAL BLOCK DIAGRAM Fast 12-bit ADC with 5.9 μs conversion time V MUX SHA REF OUT/ DD OUT IN REF IN Eight single-ended analog input channels Selection of input ranges: V SIGNAL IN1 2kΩ SCALING1 2.5V ±10 V for AD7890-10 REFERENCE V SIGNAL 0 V to 4.096 V for AD7890-4 IN2 SCALING1 0 V to 2.5 V for AD7890-2 VIN3 SIGNAL SCALING1 C Allows separate access to multiplexer and ADC EXT VIN4 SIGNAL On-chip track/hold amplifier SCALING1 MUX On-chip reference VIN5 SIGNAL SCALING1 High-speed, flexible, serial interface CONVST VIN6 SIGNAL 12-BIT Single supply, low-power operation (50 mW maximum) SCALING1 ADC Power-down mode (75 μW typ) VIN7 SIGNAL SCALING1 TRACK/HOLD GENERAL DESCRIPTION VIN8 SIGNAL SCALING1 OUTPUT/CONTROL REGISTER AD7890
The AD7890 is an 8-channel 12-bit data acquisition system. The
CLOCK
1 00 part contains an input multiplexer, an on-chip track/hold 7- 35 01 amplifier, a high speed 12-bit ADC, a 2.5 V reference, and a
AGND AGND DGND CLK SCLK TFS RFS DATA DATA SMODE
high speed, serial interface. The part operates from a single 5 V
IN OUT IN
supply and accepts an analog input range of ±10 V (AD7890-10),
1NO SCALING ON AD7890-2
0 V to 4.096 V (AD7890-4), and 0 V to 2.5 V (AD7890-2). Figure 1. The multiplexer on the part is independently accessible. This Power dissipation in normal mode is low at 30 mW typical and the allows the user to insert an antialiasing filter or signal part can be placed in a standby (power-down) mode if it is not conditioning, if required, between the multiplexer and the required to perform conversions. The AD7890 is fabricated in ADC. This means that one antialiasing filter can be used for all Analog Devices, Inc.’s Linear Compatible CMOS (LC2MOS) eight channels. Connection of an external capacitor allows the process, a mixed technology process that combines precision user to adjust the time given to the multiplexer settling to bipolar circuits with low power CMOS logic. The part is available include any external delays in the filter or signal conditioning in a 24-lead, 0.3" wide, plastic or ceramic dual-in-line package or in circuitry. a 24-lead small outline package (SOIC_W). Output data from the AD7890 is provided via a high speed
PRODUCT HIGHLIGHTS
bidirectional serial interface port. The part contains an on-chip 1. Complete 12-Bit Data Acquisition System-on-a-Chip. control register, allowing control of channel selection, The AD7890 is a complete monolithic ADC combining an conversion start, and power-down via the serial port. Versatile, 8-channel multiplexer, 12-bit ADC, 2.5 V reference, and a high speed logic ensures easy interfacing to serial ports on track/hold amplifier on a single chip. microcontrollers and digital signal processors. 2. Separate Access to Multiplexer and ADC. In addition to the traditional dc accuracy specifications such as The AD7890 provides access to the output of the linearity, full-scale, and offset errors, the AD7890 is also multiplexer allowing one antialiasing filter for 8 channels— specified for dynamic performance parameters including a considerable savings over the 8 antialiasing filters required if harmonic distortion and signal-to-noise ratio. the multiplexer is internally connected to the ADC. 3. High Speed Serial Interface. The part provides a high speed serial interface for easy connection to serial ports of microcontrollers and DSP processors.
Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
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