Features and Benefits
- VOUT = VY (VZ divided by VX)m Transfer Function
- Wide Dynamic Range (Denominator) -1000:1
- Simultaneous Multiplication and Division
- Resistor-Programmable Powers and Roots
- No External Trims Required
- Low Input Offsets <100 µV
- Low Error ±0.25% of Reading (100:1 Range)
- +2 V and +10 V On-Chip References
- Monolithic Construction
The AD538 is a monolithic real-time computational circuit which provides precision analog multiplication, division, and exponentiation. The combination of low input and output offset voltages and excellent linearity results in accurate computation over an unusually wide input dynamic range. Laser wafer trimming makes multiplication and division with errors as low as 0.25% of reading possible, while typical output offsets of 100 microV or less add to the overall off-the-shelf performance level. Real-time analog signal processing is further enhanced by the device's 400 kHz bandwidth.
The AD538's overall transfer function is Vo=Vy(Vz/Vx)m. Programming a particular function is via pin strapping. No external components are required for one-quadrant (positive input) multiplication and division. Two-quadrant (bipolar numerator) division is possible with the use of external level shifting and scaling resistors. The desired scale factor for both multiplication and division can be set using the on-chip +2 V or +10 V references, or controlled externally to provide simultaneous multiplication and division. Exponentiation with an M value from 0.2 to 5 can be implemented with the addition of one or two external resistors.
Direct log ratio computation is possible by utilizing only the log ratio and output sections of the chip. Access to the multiple summing junctions adds further to the AD538's flexibility. Finally, a wide power-supply range of ±4.5 V to ±18 V allows operation from standard ±5 V, ± 12 V and ± 15 V supplies.
The AD538 is available in two accuracy grades (A and B) over the industrial (-25°C to +85°C) temperature range and one grade (S) over the military (-55°C to +125°C) temperature range. The device is packaged in an 18-pin TO-118 hermetic size-brazed ceramic DIP. A-grade chips are also available.
- One- or two-quadrant multiply/divide
- Log ratio computation
- Squaring/square rooting
- Trigonometric function approximations
- Linearization via curve fitting
- Precision AGC
- Power functions
Product Lifecycle Not Recommended for New Designs
This designates products ADI does not recommend broadly for new designs.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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