Analog Devices Inc. AD536ASD/883B

Overview

AD536ASD/883B from Analog Devices is a hermetically sealed, military-grade true RMS-to-DC converter IC in a 14-lead ceramic DIP (CERDIP) package, rated for −55°C to +125°C operation, with ±5 mV ± 0.5% total error, 450 kHz bandwidth at 100 mV rms input, and integrated dB output pin. It computes true rms of complex ac/dc waveforms for precision power measurement in aerospace instrumentation and high-reliability test equipment.

For engineers reviewing the AD536ASD/883B datasheet, AD536ASD/883B pinout, AD536ASD/883B application, or AD536ASD/883B equivalent, key selection considerations include extended temperature performance, crest factor compensation up to 7, laser-trimmed accuracy without external trims, dual- or single-supply operation (±3 V to ±18 V or +5 V to +36 V), and availability of buffered voltage, current (40 μA/V rms), and logarithmic (−3 mV/dB) outputs.

Technical Context

The AD536ASD/883B implements an implicit rms computation using an absolute value circuit, squarer/divider, current mirror, and low-pass averaging network formed by the external CAV capacitor. Its architecture avoids dynamic range limitations of direct analog computation while maintaining linearity across wide crest factors.

It features a dedicated dB output derived from the emitter of Q3, buffered by Q5, enabling 60 dB dynamic range with externally adjustable 0 dB reference (IREF = 5–80 μA). The device supports unbuffered voltage output (across internal 25 kΩ), buffered voltage output (Pin 6), and current output (Pin 8), each with defined scale factors and temperature coefficients.

Key Specifications

Pinout & Package

AD536ASD/883B is housed in a 14-lead hermetically sealed ceramic DIP (CERDIP, Q-14 package), qualified per MIL-STD-883 with burn-in and radiation hardness assurance. Pin layout matches standard DIP footprint with 0.3" width and 0.1" lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar true RMS conversion applications.

Compared with AD637JRZ and MAX4207ETA+, the AD536ASD/883B uniquely combines extended temperature operation, crest factor 7 support, and integrated dB output in a hermetically sealed package-making it irreplaceable for aerospace, defense, and industrial harsh-environment deployments where all three attributes are simultaneously mandated.

Availability

AD536ASD/883B is available at Aetrix Electronics and suitable for aerospace power monitoring, high-temperature test equipment, avionics signal integrity analysis, military radar pulse detection, and downhole instrumentation requiring stable component supply across extended temperature and long product lifecycles.

Supply support for AD536ASD/883B 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, founded in 1965 and headquartered in Wilmington, MA.

The AD536A product line was engineered specifically for precision true RMS measurement in mission-critical analog systems where temperature stability, crest factor resilience, and multi-output flexibility are non-negotiable-targeting aerospace, defense, and industrial test instrumentation markets.

FAQ

What is the maximum input voltage the AD536ASD/883B can withstand without damage?

The AD536ASD/883B has an absolute maximum continuous nondestructive input level of ±25 V peak across all supply voltages, as specified in the Absolute Maximum Ratings table. This rating applies regardless of whether the device is powered or unpowered, and the input circuitry remains protected even during supply loss events. For reliable operation within specifications, input signals should remain within the continuous RMS level limits: 0–7 V rms on ±15 V supplies or 0–2 V rms on ±5 V supplies.

Does the AD536ASD/883B require external trimming to achieve its rated accuracy?

No, the AD536ASD/883B is laser trimmed at wafer level to minimize input/output offset voltage, optimize waveform symmetry, and ensure full-scale accuracy at 7 V rms - eliminating the need for external trims in standard applications. External trimming (via R1 and R4 in Figure 16) is optional and only recommended when optimizing performance for reduced signal ranges or compensating for system-level drift; doing so introduces a ±1.5% scale factor adjustment range but is not required to meet the datasheet's ±5 mV ± 0.5% total error specification.

Can the AD536ASD/883B operate from a single supply, and what are the constraints?

Yes, the AD536ASD/883B supports single-supply operation from +5 V to +36 V. In this configuration, the COM pin must be biased to approximately one-third of the supply voltage using a high-value resistor divider (e.g., 10 kΩ and 20 kΩ) to maintain input stage symmetry. AC inputs require coupling capacitor C2 (e.g., 1 μF for 10 Hz cutoff), while DC inputs may connect directly. Output swing is reduced: 0–+2 V on +5 V supply, scaling linearly up to 0–+11 V on ±15 V dual supplies.

What is the function of the CAV pin on the AD536ASD/883B, and how is its capacitor value selected?

The CAV pin connects to an external capacitor that sets the averaging time constant for RMS computation. Its value determines low-frequency accuracy, ripple amplitude, and settling time: a 4 μF capacitor yields 0.1% additional error at 10 Hz and 1% error at 3 Hz. The time constant is 25 ms/μF (per datasheet Table 1), so CAV = 25 ms / f_3dB. For example, a 10 Hz low-frequency limit requires CAV = 2.5 μF. Ceramic or film capacitors with tight tolerance and low leakage are recommended to preserve accuracy.

How does the dB output of the AD536ASD/883B work, and what external components are needed?

The dB output (Pin 5) delivers −3 mV/dB relative to a user-defined 0 dB reference level set by external reference current IREF (5–80 μA). To configure, connect IREF to the emitter of Q5 (via external op amp or precision current source) and adjust R1 (Figure 7) until dB output = 0 V at the desired 1 V rms input. Temperature compensation is achieved using a +3300 ppm/°C resistor (e.g., Precision Resistor Co. AT35) in series with R2. No additional active components are required for basic dB scaling.