Part A
AD637ARZ
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 7762 PCS
- Package
- SOIC-16
- Series
- PMIC-RMS-DC 동글
Replacement verdict
Compatible functional replacement candidate
The AD637ARZ and AD637KR are functionally equivalent true RMS-to-DC converters sharing the same core architecture, package footprint, and operating temperature range, making them viable substitutes in most precision RMS measurement applications. The primary distinction lies in the specified accuracy grade, where the AD637KR offers tighter factory-trimmed linearity and total error specifications than the AD637ARZ. Designers should confirm that the accuracy tolerance of the AD637ARZ satisfies the target measurement budget before substituting it for the AD637KR in high-precision instrumentation designs.
Package Type
High match
Operating Temperature Range
High match
Accuracy Grade
Validation required
Supply Voltage Range
High match
Parts at a glance
Part B
AD637KR
아날로그 디바이스(주)
- Lifecycle
- Active
- Stock
- 5379 PCS
- Package
- SOIC-16
- Series
- PMIC-RMS-DC 동글
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD637ARZ | AD637KR | Why it matters |
|---|---|---|---|
| Package / Mounting Type | 20-Lead SOIC (Surface Mount) | 14-Lead PDIP (Through-Hole) | Different footprints and mounting styles mean the parts are not drop-in replacements on the same PCB; layout and assembly must change. |
| Operating Temperature Range | -40°C to +85°C | 0°C to +70°C | The wider industrial temperature range of the ARZ allows use in harsher environments where the commercial-grade KR may not be specified. |
| Grade / Accuracy Class | A grade (industrial) | K grade (commercial) | Grade determines guaranteed accuracy and temperature performance; substituting one grade for another may violate accuracy specifications. |
| Pin Count | 20 | 14 | Different pin counts indicate different package outlines and pinouts, preventing direct board-level interchange. |
| Package Body Width / Form Factor | SOIC wide-body surface-mount | Standard 0.3" PDIP | Board space, solderability, and reflow vs. through-hole assembly differ, affecting manufacturability and mechanical fit. |
| Thermal Resistance (θJA) | Lower (SOIC, depends on layout) | Higher (PDIP) | Thermal behavior affects power dissipation limits and long-term reliability in RMS-to-DC conversion applications. |
| Lead Finish / RoHS Status | RoHS-compliant (Z suffix) | Non-RoHS (standard PDIP) | RoHS compliance is a regulatory and procurement requirement; non-compliant parts may be restricted in many markets. |
| Supply Voltage Range | ±3 V to ±18 V (dual supply) | ±3 V to ±18 V (dual supply) | Identical supply requirements mean the electrical operating envelope is the same, easing circuit reuse despite package differences. |
| Function / Core Architecture | True RMS-to-DC converter | True RMS-to-DC converter | Both share the same core RMS conversion function, so the primary signal-processing behavior is equivalent. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD637ARZ | AD637KR |
|---|---|---|
| Part Status | Active | Obsolete |
| Supply Current | 2.2 mA | 2.2 mA |
| Voltage - Supply | ±3V ~ 18V | ±3.0V ~ 18V |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the main differences between the AD637ARZ and AD637KR?
Both devices are RMS-to-DC converters from Analog Devices in the same functional family, but they differ in grade and package. The AD637ARZ is the A-grade version supplied in a 16-lead SOIC (R-16) package, while the AD637KR is the K-grade version supplied in a 14-lead CERDIP (D-14) package. The grade suffix denotes different guaranteed accuracy specifications, and the package difference affects PCB footprint and thermal/assembly considerations.
Are the AD637ARZ and AD637KR electrically interchangeable in an existing design?
They are not drop-in replacements for each other. The AD637ARZ uses a 16-lead SOIC footprint and the AD637KR uses a 14-lead CERDIP footprint, so the PCB land patterns differ. In addition, the A and K grades carry different guaranteed accuracy limits, so a design qualified for one grade should be re-validated against the datasheet limits of the other before substitution.
What is the function of the AD637 series devices?
The AD637 is a complete, high-accuracy monolithic RMS-to-DC converter that computes the true root-mean-square value of an input waveform. It provides a DC output proportional to the RMS value and is used in applications such as AC measurement, waveform analysis, and instrumentation where true RMS conversion is required.
Do the AD637ARZ and AD637KR support the same supply voltage range?
Both devices are specified for dual-supply operation in the range of ±3 V to ±18 V, consistent with the AD637 datasheet. The supply range is a family-level specification, so the difference between the A and K grades is in guaranteed accuracy, not in the rated supply window.
How do the accuracy grades of the AD637ARZ and AD637KR differ?
The A and K suffixes indicate different guaranteed accuracy grades within the AD637 family. The A grade (AD637ARZ) offers tighter guaranteed accuracy specifications than the K grade (AD637KR). Designers should consult the AD637 datasheet grade table for the exact error limits applicable to each grade before selecting one for a precision application.
Which package should be chosen for new designs, the AD637ARZ or AD637KR?
For new surface-mount designs, the AD637ARZ in the 16-lead SOIC package is generally preferred because SOIC is compatible with automated SMT assembly. The AD637KR in the 14-lead CERDIP package is a through-hole hermetic package typically chosen for legacy boards, prototyping, or environments requiring a ceramic package. Package selection should follow the assembly process and reliability requirements of the target design.
Are the AD637ARZ and AD637KR RoHS compliant?
The AD637ARZ is supplied in a RoHS-compliant SOIC package, as indicated by the "Z" suffix in the ordering code, which denotes lead-free/RoHS-compliant construction. The AD637KR uses a CERDIP package and its RoHS status should be confirmed against the specific manufacturer ordering guide, since CERDIP parts are not uniformly classified as RoHS compliant.