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Analog Devices Inc. AD538BD
- Part No.:
- AD538BD
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog Multipliers, Dividers
- Package:
- 18-CDIP (0.300", 7.62mm)
- Datasheet:
-
AD538BD.pdf
- Description:
- IC MULT/DIV REALTIME ACU 18-CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,559
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Product details
Overview
AD538BD from Analog Devices is a monolithic real-time analog computational unit (ACU) performing precision multiplication, division, and exponentiation with VO = VY(VZ/VX)m. It delivers ±0.25% of reading error (100:1 input range), 400 kHz small-signal bandwidth, and operates from ±4.5 V to ±18 V supplies. Used in transducer linearization, log-ratio computation, and AGC loops where wide dynamic range analog signal processing is required.
For engineers reviewing the AD538BD datasheet, AD538BD pinout, AD538BD application, or AD538BD equivalent, this page provides verified functional identity, confirmed 18-lead TO-118 package mapping, validated pin roles, exact transfer function behavior, and two rigorously cross-checked alternative parts for analog computation applications requiring ≤0.25% reading error and ≥400 kHz bandwidth.
Technical Context
The AD538BD implements real-time analog computation via cascaded logarithmic and antilogarithmic stages: VX and VZ feed independent log amplifiers whose differential output at Pin 3 (B) yields ln(VZ/VX); this is scaled by factor m (0.2–5) and summed with ln(VY) before antilog conversion at Pin 8 (VO). Its architecture enables simultaneous multiplication and division without external trims.
Laser wafer-trimmed internal references (+2 V unbuffered at Pin 5, +10 V buffered at Pin 4) enable precise scaling; input modes include voltage (VX/VY/VZ) and current (IX/IY/IZ); operation supports one-quadrant (positive-only) and two-quadrant (bipolar numerator) division via external level-shifting networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Transfer Function | VO = VY(VZ/VX)m; enables real-time analog multiplication, division, and exponentiation with programmable power m |
| Total Error (100:1 Range) | ±0.25% of reading + ±100 µV; guarantees high accuracy over 100 mV–10 V inputs without calibration |
| Small-Signal Bandwidth | 400 kHz; supports real-time processing of fast-varying analog signals such as sensor outputs or control loop feedback |
| Supply Voltage Range | ±4.5 V to ±18 V; compatible with standard industrial rails (±5 V, ±12 V, ±15 V) without external regulation |
| Exponent Range (m) | 0.2 to 5.0; allows squaring, square-rooting, cubing, and arbitrary power functions using one or two external resistors |
| Reference Outputs | +10 V buffered (Pin 4), +2 V unbuffered (Pin 5); laser-trimmed for ±15 mV accuracy, enabling precise scaling without external references |
| Input Offset Voltage | <100 µV; minimizes zero-error contribution in low-level signal computation (e.g., microvolt-level transducer outputs) |
Pinout & Package
AD538BD is housed in an 18-lead hermetic TO-118 side-brazed ceramic DIP package, rated for industrial temperature range (−25°C to +85°C), with isolated signal and power ground pins for noise-sensitive analog computation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IZ) | Current input for Z multiplicand | Accepts current-mode Z input; used in current-based computation configurations with 25 kΩ internal scaling resistor |
| 2 (VZ) | Voltage input for Z multiplicand | Direct voltage input path to log amplifier; supports 100 mV–10 V range with minimal offset impact |
| 3 (B) | Log ratio differential amplifier output | Provides ln(VZ/VX); accessible for standalone log-ratio applications or external scaling before antilog stage |
| 4 (+10V) | +10 V buffered reference output | Laser-trimmed, low-impedance source for scaling; usable directly as VY or VX in one-quadrant multiplier/divider |
| 5 (+2V) | +2 V unbuffered reference output | High-impedance reference; requires >500 kΩ load for <1% error; selectable scaling alternative to +10 V |
| 8 (VO) | Analog computation output | Final antilog output; ±11 V swing into 2 kΩ load; designed for direct interface with ADCs or downstream op-amp stages |
| 9 (I) | Summing junction input to output amplifier | Accepts externally conditioned log-domain signals; enables custom gain/offset insertion before final antilog conversion |
| 10 (VY) | Voltage input for Y multiplicand | Primary scaling input; determines overall gain magnitude; tied to reference for fixed-scale multiplication/division |
| 11 (IY) | Current input for Y multiplicand | Current-mode Y input; used with IZ/IX for fully current-driven computation, reducing voltage noise sensitivity |
| 12 (C) | Antilog input (log-domain sum node) | Receives scaled ln(VZ/VX) + ln(VY); internal connection point for modifying exponent m via external resistors on Pins A/D |
| 14 (SIGNAL GND) | Low-level analog ground return | Separate from power ground to prevent digital or supply noise coupling into sensitive log-ratio circuitry |
| 15 (VX) | Voltage input for X multiplicand (denominator) | Denominator input in division; sets dynamic range limit; error contribution scales with (VY + VZ)/VX term |
| 16 (IX) | Current input for X multiplicand | Current-mode denominator input; used with IX/IZ/IY for fully current-based computation topology |
| 17 (D), 18 (A) | Exponent programming terminals | Resistor-connected nodes to set m value (0.2–5); Pin A to Pin D resistance defines exponent per Figure 16 |
Key Features
| Feature | Design Value |
|---|---|
| Monolithic real-time analog computation | Eliminates hybrid/module assembly; ensures matched thermal drift and long-term stability in embedded instrumentation |
| No external trims required | Laser wafer trimming achieves ±0.25% reading error out-of-box-reduces production test time and calibration cost |
| Wide denominator dynamic range (1000:1) | Supports VX inputs from 10 mV to 10 V while maintaining accuracy-enables high-resolution ratio measurement across decades |
| Simultaneous multiplication and division | Single device computes VO = VY × (VZ/VX); reduces component count vs. discrete multiplier + divider cascades |
| On-chip +2 V / +10 V references | Removes need for external precision references; simplifies PCB layout and improves system-level accuracy consistency |
| Voltage and current input modes | Flexible interface options: accept sensors with voltage outputs (e.g., RTDs) or current outputs (e.g., 4–20 mA loops) directly |
Applications
| Transducer Linearization | Log Ratio Computation |
|---|---|
Use Scenario: Compensating nonlinear output of pressure or temperature transducers with exponential response curves. IC Role / Device Role / Timing Role: Real-time analog computation unit executing VO = VY(VZ/VX)m to invert sensor nonlinearity. Use Value: Achieves ±0.25% linearity correction over 80 dB input range without digital processing or lookup tables. |
Use Scenario: Computing ratio of two chemical concentration sensor outputs in analytical instrumentation. IC Role / Device Role / Timing Role: Dedicated log-ratio subsystem using Pins B and C to generate VO ∝ ln(VZ/VX). Use Value: Delivers ±0.5% log-domain accuracy across three decades (10 mV–10 V), eliminating ADC quantization errors in ratio measurement. |
| Square Root Extraction | Precision AGC Loop |
Use Scenario: Generating RMS-equivalent voltage from rectified AC waveform in power monitoring systems. IC Role / Device Role / Timing Role: Exponent-controlled analog processor configured with m = 0.5 via Pins A/D resistors. Use Value: Provides 280 kHz bandwidth square root with ±2 mV ±0.2% error over 10 mV–10 V input-faster than digital RMS ICs. |
Use Scenario: Maintaining constant output amplitude in RF receiver front-ends despite varying input signal strength. IC Role / Device Role / Timing Role: Closed-loop analog divider where VO controls variable-gain amplifier bias based on VZ/VX feedback. Use Value: Enables 400 kHz AGC response with <100 µV offset-critical for wide-dynamic-range communication systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar analog computation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD538AD | Higher total error: ±0.5% of reading + ±200 µV (vs. BD's ±0.25% + ±100 µV); same pinout, package, and transfer function | Acceptable where 0.5% accuracy suffices; lower cost for less demanding linearization or AGC tasks | Select AD538AD when budget constraints outweigh need for highest accuracy in industrial-grade designs. |
| MPY100KP | Fixed-function analog multiplier only (no division/exponentiation); ±0.25% error but limited to VO = K·VX·VY; no log-ratio capability | Only suitable for pure multiplication; cannot replace AD538BD in division, square-root, or log-ratio circuits | Choose MPY100KP only if application requires only analog multiplication and space/cost preclude using AD538BD's full feature set. |
Compared with AD538AD and MPY100KP, the AD538BD uniquely combines division, exponentiation, and log-ratio computation in one monolithic IC with guaranteed 0.25% reading accuracy-making it irreplaceable in multi-function analog signal conditioning where circuit count and thermal matching are critical.
Availability
AD538BD is available at Aetrix Electronics and suitable for transducer linearization, log-ratio instrumentation, square-root extraction, precision AGC loops, and analog power function generation requiring stable component supply across extended industrial temperature ranges.
Supply support for AD538BD includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, communications, automotive, and healthcare markets since 1965.
The AD538 product line delivers monolithic real-time analog computational units for applications demanding precision ratio computation, exponentiation, and wide-dynamic-range signal processing without digital intervention.
FAQ
What is the primary transfer function implemented by the AD538BD?
The AD538BD implements the real-time analog transfer function VO = VY(VZ/VX)m, where m is a programmable exponent ranging from 0.2 to 5.0. This enables simultaneous multiplication, division, and exponentiation in a single monolithic device. The AD538BD achieves this through cascaded logarithmic and antilogarithmic stages with laser-trimmed internal references. Its architecture supports both voltage and current input modes, making it suitable for transducer linearization and precision AGC applications where the AD538BD's 0.25% reading accuracy is critical.
How does the AD538BD achieve ±0.25% reading accuracy without external trims?
The AD538BD achieves ±0.25% reading accuracy (over 100 mV–10 V input range) through laser wafer trimming of its internal log-ratio and antilog stages, reference buffers, and scaling resistors. This factory calibration eliminates the need for user-adjustable trims in end equipment. The AD538BD's low 100 µV typical output offset and matched transistor pairs ensure thermal stability across −25°C to +85°C. Unlike untrimmed multipliers, the AD538BD maintains this accuracy without recalibration-even in high-reliability industrial systems where the AD538BD is deployed for long-term analog computation tasks.
Can the AD538BD perform two-quadrant division, and what external components are required?
Yes, the AD538BD supports two-quadrant division (bipolar numerator) using external level-shifting resistors to offset the VZ input relative to VX. As shown in Figure 14 of the datasheet, a 35 kΩ/25 kΩ resistor network adds VX to VZ, enabling bipolar VZ inputs while maintaining VO = 10 V × (VZ/VX) after offset correction. A trim potentiometer (R2) nulls residual offset at Pin 9 (I). This configuration requires no change to the AD538BD itself-only passive external components-and preserves the AD538BD's 400 kHz bandwidth for denominator inputs ≥2 mV.
What are the key differences between the +2 V and +10 V reference outputs on the AD538BD?
The AD538BD provides two internal references: +10 V (Pin 4, buffered, low-impedance) and +2 V (Pin 5, unbuffered, ~5 kΩ output impedance). The +10 V reference can drive moderate loads directly, while the +2 V reference requires >500 kΩ loading to maintain <1% error. Both are laser-trimmed to ±15 mV accuracy. In practice, the +10 V reference is used for high-accuracy scaling in one-quadrant multiplier/divider configurations, whereas the +2 V reference serves as a low-power option or adjustable reference (via external resistive divider between Pins 4 and 5) when the AD538BD is configured for custom scale factors.
How is exponent (m) programmed on the AD538BD, and what resistor values are needed for square root?
Exponent m on the AD538BD is programmed by connecting resistors between Pins A (18) and D (17) to set the log-ratio stage gain. For square root (m = 0.5), the datasheet specifies a resistor divider: RB = 100 Ω and RC = 100 Ω (Figure 16), connected between Pin B (3) and Pin C (12). These must be 1% metal-film resistors for optimal linearity. This configuration scales the ln(VZ/VX) signal by 0.5 before antilog conversion, yielding VO ∝ √(VZ/VX). The AD538BD's ability to set m from 0.2 to 5.0 with simple external resistors makes it uniquely flexible among analog computational ICs.
AD538BD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 18-CDIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Analog Computational Unit
- Number of Bits/Stages:
- 4-Quadrant
- Supplier Device Package:
- 18-SBDIP
AD538BD FAQ
1.How can I place an order for AD538BD through Aetrix?
Please submit a Request for Quotation (RFQ) for AD538BD on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD538BD reliable?
The price and inventory of AD538BD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD538BD is usually 5 days.
3.What payment methods are accepted for AD538BD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD538BD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD538BD?
AD538BD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD538BD order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD538BD?
For technical support, including AD538BD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD538BD requirements.
6.How does Aetrix verify that AD538BD is sourced from the original manufacturer or authorized distributors?
All AD538BD products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD538BD meets industry standards.
7.What is the process for return or replacement of AD538BD?
All AD538BD units undergo pre-shipment inspection (PSI). If there is an issue with AD538BD, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD538BD part is unused and in its original packaging.
Return procedure for AD538BD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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