a FEATURES Four 8-Bit DACs with Output Amplifiers Skinny 20-Pin DIP, SOIC and 20-Terminal Surface Mount Packages Microprocessor Compatible TTL/CMOS Compatible No User Trims Extended Temperature Range Operation Single Supply Operation Possible
LC2MOS Quad 8-Bit D/A Converter AD7226 FUNCTIONAL BLOCK DIAGRAM
APPLICATIONS Process Control Automatic Test Equipment Automatic Calibration of Large System Parameters, e.g., Gain/Offset
The AD7226 contains four 8-bit voltage-output digital-toanalog converters, with output buffer amplifiers and interface logic on a single monolithic chip. No external trims are required to achieve full specified performance for the part.
1. DAC-to-DAC Matching Since all four DACs are fabricated on the same chip at the same time, precise matching and tracking between the DACs is inherent.
Separate on-chip latches are provided for each of the four D/A converters. Data is transferred into one of these data latches through a common 8-bit TTL/CMOS (5 V) compatible input port. Control inputs A0 and A1 determine which DAC is loaded when WR goes low. The control logic is speed-compatible with most 8-bit microprocessors.
2. Single Supply Operation The voltage mode configuration of the DACs allows the AD7226 to be operated from a single power supply rail.
Each D/A converter includes an output buffer amplifier capable of driving up to 5 mA of output current. The amplifiers’ offsets are laser-trimmed during manufacture, thereby eliminating any requirement for offset nulling. Specified performance is guaranteed for input reference voltages from +2 V to +12.5 V with dual supplies. The part is also specified for single supply operation at a reference of +10 V. The AD7226 is fabricated in an all ion-implanted high speed Linear Compatible CMOS (LC2MOS) process which has been specifically developed to allow high speed digital logic circuits and precision analog circuits to be integrated on the same chip.
3. Microprocessor Compatibility The AD7226 has a common 8-bit data bus with individual DAC latches, providing a versatile control architecture for simple interface to microprocessors. All latch enable signals are level triggered. 4. Small Size Combining four DACs and four op amps plus interface logic into a 20-pin DIP or SOIC or a 20-terminal surface mount package allows a dramatic reduction in board space requirements and offers increased reliability in systems using multiple converters. Its pinout is aimed at optimizing board layout with all the analog inputs and outputs at one end of the package and all the digital inputs at the other.
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