AD538ADZ

AD538ADZ FEATURES

VO = VY(VZ/VX)m transfer functionWide dynamic range (denominator) −1000:1Simultaneous multiplication and divisionResistor-programmable powers and rootsNo external trims requiredLow input offsets <100 μVLow error ±0.25% of reading (100:1 range)Monolithic constructionReal-time analog multiplication, division andexponentiationHigh accuracy analog division with a wide input dynamic rangeOn board +2 V or +10 V scaling referenceVoltage and current (summing) input modesMonolithic construction with lower cost and higherreliability than hybrid and modular circuits

AD538ADZ GENERAL DESCRIPTION

The AD538 is a monolithic real-time computational circuitthat provides precision analog multiplication, division, andexponentiation. The combination of low input and output offsetvoltages and excellent linearity results in accurate computationover an unusually wide input dynamic range. Laser wafertrimming makes multiplication and division with errors as lowas 0.25% of reading possible, while typical output offsets of100 μV or less add to the overall off-the-shelf performance level.Real-time analog signal processing is further enhanced by the400 kHz bandwidth of the device.The overall transfer function of the AD538 is VO = VY(VZ/VX)m.Programming a particular function is via pin strapping. Noexternal components are required for one-quadrant (positiveinput) multiplication and division. Two-quadrant (bipolarnumerator) division is possible with the use of external levelshifting and scaling resistors. The desired scale factor for bothmultiplication and division can be set using the on-chip +2 V or+10 V references, or controlled externally to provide simultaneousmultiplication and division. Exponentiation with an m valuefrom 0.2 to 5 can be implemented with the addition of one ortwo external resistors.Direct log ratio computation is possible by using only the logratio and output sections of the chip. Access to the multiplesumming junctions adds further to the flexibility of the AD538.Finally, a wide power supply range of ±4.5 V to ±18 V allowsoperation from standard ±5 V, ±12 V and ±15 V supplies.The AD538 is available in two accuracy grades (A and B) overthe industrial (−25°C to +85°C) temperature range and onegrade (S) over the military (−55°C to +125°C) temperaturerange. The device is packaged in an 18-lead TO-118 hermeticside-brazed ceramic DIP. A-grade chips are also available.

AD538ADZ APPLICATIONS

One- or two-quadrant multiply/divideLog ratio computationSquaring/square rootingTrigonometric function approximationsLinearization via curve fittingPrecision AGCPower functions