Analog Devices Inc. AD536ASH

Overview

AD536ASH from Analog Devices is a monolithic true RMS-to-DC converter IC designed for precision measurement of complex ac/dc waveforms in high-reliability instrumentation. It delivers ±0.5% maximum total error, 450 kHz bandwidth at 100 mV rms input, crest factor compensation up to 7, dB output with 60 dB dynamic range, and operates across −55°C to +125°C.

For engineers reviewing the AD536ASH datasheet, AD536ASH pinout, AD536ASH application, or AD536ASH equivalent, key selection criteria include extended temperature operation, laser-trimmed accuracy without external trims, dual- or single-supply flexibility (±3 V to ±18 V or +5 V to +36 V), and integrated dB output requiring only external IREF for level setting.

Technical Context

The AD536ASH implements an implicit RMS computation via squarer/divider and current mirror architecture, eliminating need for explicit square-root extraction. Its absolute value circuit enables accurate rectification of low-level and asymmetric waveforms, while internal laser trimming minimizes dc reversal error and optimizes full-scale accuracy at 7 V rms.

It features a dedicated dB output derived from the emitter of Q3, buffered by Q5, with scale factor −3 mV/dB and temperature coefficient −0.033 dB/°C. An external averaging capacitor (CAV) sets low-frequency accuracy and settling time, with 25 ms/μF time constant.

Key Specifications

Pinout & Package

AD536ASH is supplied in a hermetically sealed 14-lead ceramic DIP (D-14) package rated for −55°C to +125°C operation. Pin layout follows standard industry DIP orientation with pins 1–7 on one side and 8–14 on the opposite.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD636JQ and MAX4206ESA+, the AD536ASH uniquely combines extended temperature operation, integrated dB output, and current-mode IOUT capability-making it the only option for high-reliability, multi-interface RMS measurement in aerospace and energy infrastructure systems.

Availability

AD536ASH is available at Aetrix Electronics and suitable for power quality analyzers, audio test equipment, industrial process controllers, and aerospace sensor modules requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AD536ASH 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 defense markets since 1965.

The AD536A family was developed to replace hybrid RMS modules with monolithic solutions offering superior accuracy, reliability, and integration - specifically targeting test & measurement, instrumentation, and high-end control systems.

FAQ

What is the maximum input voltage the AD536ASH can handle without damage?

The AD536ASH has an absolute maximum continuous nondestructive input level of ±25 V peak across all supply voltages. This rating applies regardless of whether operated from dual ±15 V or single +24 V supplies. Transient overloads within this limit will not degrade performance or cause latch-up. The input circuitry is fully protected and remains functional even if supply voltage is lost while VIN remains connected to external circuitry.

Does the AD536ASH require external trimming to achieve its specified ±0.5% accuracy?

No, the AD536ASH does not require external trimming to achieve its specified ±0.5% maximum total error. It is laser trimmed at wafer level to minimize input/output offset, optimize dc reversal symmetry, and calibrate full-scale accuracy at 7 V rms. External trims (e.g., R1 and R4 in Figure 16) are optional and only needed when optimizing for reduced input ranges or tighter system-level tolerances beyond the datasheet specification.

How is the 0 dB reference level set on the AD536ASH dB output pin?

The 0 dB reference level on the AD536ASH dB output is set by supplying a precise reference current (IREF) to the emitter of Q5 via an external resistor network. For 0 dB = 1 V rms, IREF must be 5–80 μA depending on grade; typical setup uses a 500 kΩ potentiometer (R1 in Figure 7) adjusted while applying 1.00 V rms to VIN until dB output reads 0.00 V. The scale factor is fixed at −3 mV/dB with temperature compensation provided by external resistors.

Can the AD536ASH operate from a single 5 V supply?

Yes, the AD536ASH supports single-supply operation from +5 V to +36 V. When powered from +5 V, the COM pin must be biased to ~1.67 V using a resistor divider (e.g., 10 kΩ to +5 V and 20 kΩ to GND), and AC input coupling requires a series capacitor (e.g., 1 μF for 10 Hz cutoff). Output swing is limited to 0–2 V, and input range reduces to 0–2 V rms continuous, but all core RMS functionality remains fully operational.

What external component is mandatory for AD536ASH to meet its full accuracy specifications?

An external averaging capacitor (CAV) connected to Pin 4 is mandatory for the AD536ASH to meet its full accuracy specifications. Its value determines low-frequency accuracy, ripple amplitude, and settling time per the 25 ms/μF time constant. For example, a 4 μF capacitor yields <0.1% additional error at 10 Hz but increases settling time to ~100 ms. No other external components are required for basic RMS operation - laser trimming eliminates need for offset or gain trims.