Analog Devices Inc. AD636JH

Overview

AD636JH from Analog Devices is a monolithic true RMS-to-DC converter IC designed for precision low-level ac/dc signal measurement in portable and battery-powered instrumentation. It delivers 200 mV full-scale output, ±1.0% total error (typical ±0.5 mV), 1.5 MHz ±3 dB bandwidth at 200 mV rms input, and operates from ±2.5 V to ±16.5 V dual supplies or +5 V to +24 V single supply - used in handheld multimeters and power quality analyzers.

For engineers reviewing the AD636JH datasheet, AD636JH pinout, AD636JH application, or AD636JH equivalent, key selection considerations include its 10-pin TO-100 metal-can package, laser-trimmed accuracy without external calibration, crest factor tolerance up to 6, dB output with 50 dB range, and IOUT current-mode output scalable to 100 μA/V rms.

Technical Context

The AD636JH implements an implicit analog RMS computation using an absolute value circuit, squarer/divider, current mirror, and averaging capacitor (CAV) to solve V_OUT = √(Avg[V_IN²]). Its architecture avoids digital sampling and supports continuous dc-coupled operation with no minimum frequency limit when CAV is selected appropriately.

It integrates a buffered input/output amplifier (±5 mA drive), dedicated dB output referenced to externally set IREF (1–50 μA), and IOUT terminal delivering 100 μA/V rms with ±20% scale factor tolerance. Input protection allows ±12 V peak transient signals even with no supply applied.

Key Specifications

Pinout & Package

AD636JH is housed in a hermetically sealed 10-pin TO-100 metal can package with center tab grounded. The package provides excellent thermal stability, EMI immunity, and long-term parameter retention in harsh environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD636JH, AD636KH offers superior accuracy but identical footprint and interface, while AD736JRZ trades dB/IOUT capability and bandwidth for smaller size and lower cost - making AD636JH the optimal balance of feature richness, ruggedness, and precision in industrial portable instruments.

Availability

AD636JH is available at Aetrix Electronics and suitable for handheld test equipment, industrial power analyzers, audio level meters, and medical biopotential monitors requiring stable component supply across extended product lifecycles.

Supply support for AD636JH 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Wilmington, MA.

The AD636 product line was engineered specifically for precision analog RMS measurement in portable, battery-operated, and high-reliability instrumentation - emphasizing low power, input robustness, and factory-trimmed accuracy without external components.

FAQ

What is the maximum input signal level the AD636JH can handle without damage?

The AD636JH withstands ±12 V peak transient inputs across all supply conditions, including zero-supply state. This overvoltage protection prevents latch-up or permanent damage during accidental probe contact with mains or high-voltage nodes - a critical safety feature in handheld multimeters where AD636JH serves as the primary RMS sensing element.

Does the AD636JH require external calibration components to achieve its specified accuracy?

No. The AD636JH is laser-trimmed at wafer level for input/output offset, waveform symmetry, and full-scale accuracy at 200 mV rms. External trims are optional only for applications demanding sub-0.5% error; the AD636JH delivers its rated ±1.0% total error out-of-box with only CAV capacitor required for averaging.

Can the AD636JH operate from a single 9 V battery?

Yes. The AD636JH supports single-supply operation from +5 V to +24 V. With a 9 V battery, connect +VS to 9 V, COM to a mid-rail bias network (e.g., two 39 kΩ resistors + 0.1 μF cap), and −VS to COM. This configuration maintains full 200 mV rms range and 800 μA quiescent draw - enabling >1000-hour operation in AD636JH-based portable meters.

How does the CAV capacitor value affect AD636JH performance?

The CAV capacitor sets the averaging time constant (25 ms/μF), directly governing low-frequency accuracy, output ripple, and settling time. For example, a 4 μF CAV yields 0.1% dc error at 10 Hz but increases 1% settling time to ~460 ms for decreasing signals - a key trade-off in AD636JH design for power quality monitoring versus audio metering.

What is the function of the IOUT pin on the AD636JH?

The IOUT pin delivers a current output proportional to input RMS voltage: 100 μA per volt rms (e.g., 200 mV rms input → 20 μA output). This enables direct interfacing with current-input log amps, optocouplers, or 4–20 mA transmitter circuits - preserving signal integrity in noisy industrial environments where AD636JH is commonly deployed.