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Analog Devices Inc. AD637JR-REEL7
- Part No.:
- AD637JR-REEL7
- Manufacturer:
- Analog Devices Inc.
- Category:
- RMS to DC Converters
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD637JR-REEL7.pdf
- Description:
- IC RMS TO DC CONVERTER 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,819
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Product details
Overview
AD637JR-REEL7 from Analog Devices is a high-precision, wideband true RMS-to-DC converter IC designed for accurate signal power measurement in test equipment and industrial instrumentation. It delivers 0.02% max nonlinearity (0–2 V rms), 8 MHz bandwidth at 2 V rms input, and computes true RMS, mean square, absolute value, and dB output across crest factors up to 10. It supports ±3 V to ±18 V dual supplies and features chip select for analog three-state operation.
For engineers reviewing the AD637JR-REEL7 datasheet, AD637JR-REEL7 pinout, AD637JR-REEL7 application, or AD637JR-REEL7 equivalent, key selection criteria include crest factor tolerance (≤1% error at CF=10), dB output calibration range (±0.3 dBV), internal trim accuracy (±0.5 mV ±0.2% reading), averaging capacitor dependency (25 ms/μF), and SOIC_W package compatibility with 16-pin layout.
Technical Context
The AD637JR-REEL7 implements an implicit analog solution to the RMS equation using a squarer/divider architecture with external averaging capacitor (CAV) feedback. Its absolute value circuit drives a current-mode squarer, whose output feeds a low-pass filter; the filtered current is fed back as denominator current to close the implicit loop: VOUT = √(VIN²)avg.
It integrates a buffered output stage (1 MHz bandwidth, 5 V/µs slew rate), dedicated dB output pin (−3 mV/dB scale factor), and chip select (CS) that reduces quiescent current from 2.2 mA to 350 µA while placing RMS OUT in high-impedance state-enabling parallel connection for multiplexed RMS measurement.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nonlinearity | 0.02% of full scale at 2 V rms - ensures minimal distortion in precision AC power measurement |
| Bandwidth | 8 MHz at 2 V rms input - supports high-frequency RMS analysis of RF envelope or switching waveforms |
| Crest Factor Error | <1% additional error up to CF=10 - enables accurate RMS reading of pulsed, clipped, or peaky signals |
| dB Output Accuracy | ±0.3 dBV from 7 mV to 7 V rms - allows direct logarithmic scaling without external conversion circuitry |
| Input Range | 0–7 V rms continuous (±15 V supply) - accommodates line-level and intermediate-signal monitoring |
| Averaging Time Constant | 25 ms per μF on CAV pin - sets low-frequency ripple and settling time; 4 μF yields 0.1% error at 10 Hz |
| Quiescent Current | 2.2 mA active / 350 µA standby - enables battery-powered handheld meters and remote sensors |
Pinout & Package
AD637JR-REEL7 is housed in a 16-lead SOIC_W (wide-body) surface-mount package, RoHS-compliant and tape-and-reel packaged (REEL7 denotes 7-inch reel). Pin count and layout match JEDEC MS-013AC, with 0.025" pitch and exposed thermal pad not connected internally.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 15) | Signal Input | Primary ac/dc input node; 6.4–9.6 kΩ input resistance; protected against ±15 V p-p transients |
| RMS OUT (Pin 11) | Main DC Output | True RMS voltage output; 0–13.5 V swing into 2 kΩ; high-impedance when CS is low |
| CAV (Pin 10) | Averaging Capacitor Connection | Connects external capacitor to set time constant (τ = 25 ms/μF); determines low-frequency accuracy and ripple |
| dB OUTPUT (Pin 7) | Logarithmic Output | Provides −3 mV/dB output referenced to user-programmable IREF (1–100 µA); ±0.3 dBV accuracy |
| CS (Pin 5) | Chip Select | Active-low control: pulls RMS OUT to high-Z and cuts supply current to 350 µA when <0.2 V |
| COMMON (Pin 3) | Analog Ground Reference | System analog common point; must be tied to low-impedance ground plane for optimal noise rejection |
| BUFF IN / BUFF OUT (Pins 1 / 16) | Buffer Interface | Configurable as input buffer (for high-Z source) or active filter; 10⁸ Ω input resistance, ±2 mV offset |
| +VS / –VS (Pins 13 / 12) | Supply Rails | Dual ±3 V to ±18 V operation; bypassing with 0.1 µF ceramic caps near pins required for stability |
Key Features
| Feature | Design Value |
|---|---|
| True RMS computation | Direct analog implementation of √(VIN²)avg - eliminates need for digital sampling, ADC, or firmware processing |
| Laser wafer trimming | Factory-trimmed accuracy (no external potentiometers required) - achieves ±0.5 mV ±0.2% total error without user calibration |
| Multi-function output | Single device provides RMS, mean square (via DEN INPUT), absolute value (no CAV), and dB outputs - reduces BOM count in multi-mode instruments |
| Chip select power-down | Reduces supply current by 84% and enables analog three-state output - supports time-division multiplexing of multiple AD637JR-REEL7 units |
| Overvoltage-protected inputs | Withstands ±15 V p-p transients even with lost supply rails - improves robustness in field-deployed test gear |
Applications
| Digital Multimeter RMS Core | RF Power Monitor Front-End |
|---|---|
Use Scenario: High-accuracy handheld or benchtop DMM measuring non-sinusoidal currents/voltages in industrial maintenance and calibration labs. IC Role / Device Role / Timing Role: Primary RMS conversion engine; accepts conditioned ac input, outputs calibrated dc voltage proportional to true signal power. Use Value: Delivers 0.02% nonlinearity and <1% crest factor error up to CF=10 - meets IEC 61000-4-30 Class A requirements for harmonic-rich waveform measurement. | Use Scenario: Real-time envelope power detection in 5G base station PA monitoring and EMC pre-compliance testing. IC Role / Device Role / Timing Role: Wideband RMS detector feeding ADC or microcontroller; operates up to 8 MHz at 2 V rms to capture modulated RF envelope dynamics. Use Value: 8 MHz bandwidth + 600 kHz at 100 mV rms enables accurate power tracking of OFDM and QAM signals without undersampling artifacts. |
| Audio Signal Analyzer Input Stage | Industrial Motor Drive Current Sensor |
Use Scenario: Professional audio analyzers measuring THD+N, loudspeaker impedance, and dynamic range across 20 Hz–20 kHz. IC Role / Device Role / Timing Role: Precision ac-coupled RMS front-end; uses CAV capacitor to set 100 ms averaging for low-frequency stability. Use Value: 0.1% error at 10 Hz (with 4 μF CAV) and ±0.3 dBV dB output enable traceable loudness and gain staging measurements. | Use Scenario: Closed-loop current sensing in servo drives and inverters where motor phase current contains PWM harmonics and DC bias. IC Role / Device Role / Timing Role: True RMS conditioner for shunt-based current sensing; rejects common-mode noise via differential input configuration. Use Value: Handles crest factors >5 from PWM switching edges and delivers stable dc output despite 10 kHz+ harmonic content - improves torque control fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar true RMS conversion applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD637KRZ-REEL | Same die, Grade K accuracy (0.02% nonlinearity), but in 14-lead CERDIP package - no REEL7 tape format, higher thermal resistance | Preferred for through-hole prototyping or military-grade hermetic sealing; unsuitable for automated SOIC pick-and-place | Select when long-term stability over −40°C to +85°C and hermetic reliability outweigh SMT assembly efficiency |
| LT1966CMS8#TRPBF | Lower bandwidth (1.5 MHz), higher nonlinearity (0.25%), no dB output or chip select - single-supply only (4.5–50 V) | Targets cost-sensitive industrial sensors where 100 kHz–1 MHz RMS suffices and dual supply is unavailable | Select only if supply constraints prohibit dual-rail operation and bandwidth needs are ≤1.5 MHz |
Compared with AD637JR-REEL7, AD637KRZ-REEL offers identical core accuracy in a legacy ceramic package with superior temperature range but no tape-and-reel automation support; LT1966CMS8#TRPBF trades bandwidth, precision, and feature set for single-supply simplicity and lower cost-making it suitable only for less demanding RMS tasks.
Availability
AD637JR-REEL7 is available at Aetrix Electronics and suitable for digital multimeters, RF power monitors, audio analyzers, and industrial motor drive current sensors requiring stable component supply, long-lifecycle assurance, and consistent parametric performance across production batches.
Supply support for AD637JR-REEL7 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, with design centers worldwide.
The AD637 product line was engineered specifically for high-fidelity, wideband RMS measurement in portable and rack-mounted test instrumentation-prioritizing accuracy, bandwidth, and integration over cost or digital interface features.
FAQ
What is the maximum input frequency supported by the AD637JR-REEL7 for accurate RMS conversion?
The AD637JR-REEL7 supports up to 8 MHz bandwidth at 2 V rms input, delivering ≤1% additional error. At lower amplitudes-such as 100 mV rms-the usable bandwidth drops to 600 kHz. These limits are defined by the ±3 dB points in the frequency response specification and assume proper supply decoupling and CAV capacitor selection per the datasheet's averaging time constant guidelines. The AD637JR-REEL7 maintains true RMS accuracy across this range without digital sampling or aliasing concerns.
Does the AD637JR-REEL7 require external trimming to achieve its specified 0.02% nonlinearity?
No, the AD637JR-REEL7 is laser wafer trimmed at Analog Devices' fabrication facility and achieves its 0.02% nonlinearity specification without any external trimming components. The device includes optional offset and scale factor trim pads (R1 and R3 in Figure 8 of the datasheet) only for applications demanding sub-0.01% residual error-typically metrology-grade systems. For standard high-accuracy instrumentation, the AD637JR-REEL7 operates fully specified out-of-the-box.
Can the AD637JR-REEL7 compute RMS values for signals with large DC offsets?
Yes, the AD637JR-REEL7 computes true RMS of ac-plus-dc waveforms inherently-it does not require AC coupling. Its input stage accepts signals ranging from 0 to 7 V rms under ±15 V supplies, including those with significant DC bias. The output represents √[(Vac + Vdc)²]avg, preserving the contribution of both components to total power. This capability is essential for motor current monitoring and switched-mode power supply output analysis.
How does the chip select (CS) pin affect the output behavior of the AD637JR-REEL7?
When the CS pin of the AD637JR-REEL7 is pulled below 0.2 V, the device enters standby mode: quiescent current drops from 2.2 mA to 350 µA, and the RMS OUT pin transitions to a high-impedance state (100 kΩ typical off-resistance). This allows multiple AD637JR-REEL7 devices to share a common output bus-enabling time-multiplexed RMS measurement without external analog switches. The output resumes normal operation within microseconds after CS is released.
Is the dB output of the AD637JR-REEL7 calibrated to a standard reference level like 1 V rms or 1 mW?
The dB output of the AD637JR-REEL7 is user-calibratable: its 0 dB point corresponds to any rms input voltage between 0.1 V and 2.0 V, set by programming the IREF current (1–100 µA) into the REF pin. For example, applying 20 µA yields 0 dB at 1 V rms (0 dBV), while 5 µA sets 0 dB at 0.25 V rms. This flexibility allows direct alignment with system-specific reference levels-such as 775 mV (0 dBm into 600 Ω) or custom thresholds in automated test equipment-without external scaling.
AD637JR-REEL7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Current - Supply:
- 2.2 mA
- Voltage - Supply:
- ±3V ~ 18V
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
AD637JR-REEL7 FAQ
1.How can I place an order for AD637JR-REEL7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD637JR-REEL7 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD637JR-REEL7 reliable?
The price and inventory of AD637JR-REEL7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD637JR-REEL7 is usually 5 days.
3.What payment methods are accepted for AD637JR-REEL7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD637JR-REEL7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD637JR-REEL7?
AD637JR-REEL7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD637JR-REEL7 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD637JR-REEL7?
For technical support, including AD637JR-REEL7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD637JR-REEL7 requirements.
6.How does Aetrix verify that AD637JR-REEL7 is sourced from the original manufacturer or authorized distributors?
All AD637JR-REEL7 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD637JR-REEL7 meets industry standards.
7.What is the process for return or replacement of AD637JR-REEL7?
All AD637JR-REEL7 units undergo pre-shipment inspection (PSI). If there is an issue with AD637JR-REEL7, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD637JR-REEL7 part is unused and in its original packaging.
Return procedure for AD637JR-REEL7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AD637JR-REEL7 Tags
-
AD8436JCPZ-R7
Analog Devices Inc.
-
LTC1966CMS8#PBF
Analog Devices Inc.
-
LTC1966CMS8#TRPBF
Analog Devices Inc.
-
LTC1967CMS8#TRPBF
Analog Devices Inc.
-
LTC1967CMS8#PBF
Analog Devices Inc.
-
AD736ARZ
Analog Devices Inc.
-
LTC1968CMS8#PBF
Analog Devices Inc.
-
LTC1968CMS8#TRPBF
Analog Devices Inc.
-
AD737JRZ-R7
Analog Devices Inc.
-
AD737JRZ
Analog Devices Inc.
-
AD8436ACPZ-R7
Analog Devices Inc.
-
AD8436ARQZ
Analog Devices Inc.
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