Part A
AD637JR
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 6307 PCS
- Package
- SOIC-16
- Series
- PMIC - RMS to DC Converters
Replacement verdict
Compatible functional replacement candidate
The AD637JR and AD637KR are functionally interchangeable true RMS-to-DC converters sharing the same pinout, package, and core architecture; the KR grade offers tighter accuracy and lower input offset specifications, making it a valid drop-in candidate where the application can benefit from improved precision, while the JR grade remains suitable for less demanding measurement tolerances.
Package and Pinout
High match
Functional Architecture
High match
Accuracy Grade
Validation required
Operating Temperature Range
High match
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD637JR | AD637KR | Why it matters |
|---|---|---|---|
| Grade / Accuracy Grade | J grade (commercial) | K grade (higher accuracy) | The K grade offers tighter accuracy specifications than the J grade, directly affecting measurement precision in RMS-to-DC conversion. |
| Total Error (RMS-to-DC, max) | ±0.5% of reading (typical spec for J grade) | ±0.2% of reading (typical spec for K grade) | Lower total error means more accurate true RMS measurements, which is critical for precision instrumentation and calibration applications. |
| Operating Temperature Range | 0°C to +70°C | 0°C to +70°C | Both share the commercial temperature range; this confirms neither is a wider-temperature industrial or military variant. |
| Package / Mounting | 14-Lead SOIC (surface mount) | 14-Lead SOIC (surface mount) | Identical package and footprint allow direct board-level substitution without layout changes. |
| Supply Voltage (dual) | ±3 V to ±18 V | ±3 V to ±18 V | Matching supply range ensures the parts are interchangeable in the same power architecture. |
| Bandwidth (RMS conversion) | 8 MHz (typical, at 200 mV rms) | 8 MHz (typical, at 200 mV rms) | Equivalent bandwidth means both handle the same signal frequency content for RMS computation. |
| Input Voltage Range | 0 to 7 V rms (full-scale) | 0 to 7 V rms (full-scale) | Same full-scale input range ensures identical dynamic range handling in the application. |
| Quiescent Supply Current | 2.2 mA (typical) | 2.2 mA (typical) | Identical power consumption supports drop-in replacement in power-sensitive designs. |
| Output Offset Voltage (max) | Higher offset limit (J grade) | Lower offset limit (K grade) | The K grade's tighter offset specification improves DC accuracy of the RMS output, important for precision measurement. |
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 | AD637JR | AD637KR |
|---|---|---|
| Part Status | Obsolete | 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 is the primary difference between the AD637JR and AD637KR?
The main difference is the specified accuracy grade. The AD637KR offers tighter accuracy specifications than the AD637JR, with the KR grade providing lower maximum error in RMS-to-DC conversion over the rated temperature range. Both are functionally identical true RMS-to-DC converters in the same package and pinout.
Are the AD637JR and AD637KR pin-compatible and package-compatible?
Yes. Both the AD637JR and AD637KR are offered in the same 16-lead SOIC package with identical pin functions, so they are pin-compatible and can use the same PCB land pattern. Substitution is possible when the tighter accuracy grade of the KR is not required.
What accuracy grades do the AD637JR and AD637KR represent?
The AD637 is specified in multiple grades; the J and K suffixes denote commercial temperature-range grades with different accuracy limits. The KR grade has tighter maximum error specifications than the JR grade. Designers should consult the Analog Devices AD637 datasheet for the exact error limits applicable to each grade.
Do the AD637JR and AD637KR share the same operating temperature range?
Yes. Both the J and K grades are commercial temperature-range devices, specified for operation from 0°C to +70°C. The difference between the two is accuracy grading, not temperature range.
Can the AD637JR be used as a drop-in replacement for the AD637KR?
Physically yes, since both are 16-lead SOIC devices with identical pinouts. However, the JR grade has looser accuracy specifications than the KR grade, so it should only be substituted where the reduced accuracy still meets the design requirements. The reverse substitution (KR for JR) is generally acceptable when the tighter grade is available.
What function do both the AD637JR and AD637KR perform?
Both are high-accuracy monolithic true RMS-to-DC converters that compute the root-mean-square value of complex input waveforms. They provide a DC output proportional to the RMS value of the input signal and are used in instrumentation, power measurement, and signal analysis applications.
Do the AD637JR and AD637KR require the same external components?
Yes. Because both grades share the same internal architecture and pinout, the external component values (such as the averaging capacitor and input/output filtering) are the same for both. The datasheet application circuits apply equally to the JR and KR grades.