Overview
The AD637JR-REEL7, produced by Analog Devices Inc., is a high-accuracy, wideband RMS-to-DC converter. This integrated circuit computes the true root mean square (rms), mean square, or absolute value of any complex AC (or AC plus DC) input waveform and provides an equivalent DC output voltage. The AD637 offers unprecedented performance in accuracy, bandwidth, and dynamic range, comparable to discrete and modular techniques. It is particularly useful because the true rms value relates directly to the power of the signal and the standard deviation of statistical signals.
Key Specifications
| Parameter | Value | Comments |
|---|---|---|
| Maximum Nonlinearity | 0.02% (0 V to 2 V rms input) | |
| Additional Error to Crest Factor of 3 | 0.10% | |
| Bandwidth | Up to 8 MHz at 2 V rms input, 600 kHz at 100 mV rms | |
| dB Output Range | 60 dB | Direct dB value of the rms output |
| Supply Voltage | ±3V to ±18V | |
| Quiescent Current | 2.2 mA (normal), 350 µA (power-down) | |
| Input Resistance | 6.4 kΩ to 9.6 kΩ | |
| Input Offset Voltage | ±0.5 mV to ±0.2 mV | |
| Temperature Range | Commercial: 0°C to 70°C, Industrial: -40°C to +85°C, Military: -55°C to +125°C | Depending on the grade (J, K, A, B, S) |
| Package Types | 14-lead SBDIP, 14-lead CERDIP, 16-lead SOIC_W |
Key Features
- High accuracy with 0.02% maximum nonlinearity for inputs from 0 V to 2 V rms.
- Wide bandwidth, allowing measurements up to 8 MHz at 2 V rms input and 600 kHz at 100 mV rms.
- Computes true rms, mean square, or absolute value of complex waveforms.
- Direct dB output with a 60 dB range, allowing for direct dB measurement.
- Externally programmable reference current to set the 0 dB reference voltage between 0.1 V and 2.0 V rms.
- Chip select/power-down feature to reduce quiescent current from 2.2 mA to 350 µA.
- High impedance output state when powered down, enabling multiple AD637s to be used as a wideband true rms multiplexer.
- Input circuitry protected from overload voltages exceeding supply levels.
- Laser wafer trimmed for rated performance without external trimming.
- On-chip buffer amplifier for input buffering or active filter configuration to reduce ac ripple.
Applications
The AD637JR-REEL7 is suitable for various precision measurement applications, including:
- Remote or handheld devices where low power consumption is critical.
- Industrial and commercial measurement systems requiring high accuracy and wide bandwidth.
- Aerospace and military applications due to its availability in military temperature grades.
- Audio and signal processing systems where accurate rms measurements are necessary.
- Power monitoring and control systems in electrical engineering.
Q & A
- What is the primary function of the AD637JR-REEL7?
The AD637JR-REEL7 computes the true root mean square (rms), mean square, or absolute value of any complex AC (or AC plus DC) input waveform and provides an equivalent DC output voltage.
- What is the maximum nonlinearity of the AD637JR-REEL7?
The maximum nonlinearity is 0.02% for inputs from 0 V to 2 V rms.
- What is the bandwidth of the AD637JR-REEL7?
The bandwidth is up to 8 MHz at 2 V rms input and 600 kHz at 100 mV rms.
- How does the chip select/power-down feature work?
The chip select feature allows the user to decrease the supply current from 2.2 mA to 350 µA during periods when the rms function is not in use, and the output goes to a high impedance state when powered down.
- What types of packages are available for the AD637JR-REEL7?
The AD637JR-REEL7 is available in 14-lead SBDIP, 14-lead CERDIP, and 16-lead SOIC_W packages.
- How is the 0 dB reference voltage set?
The 0 dB reference voltage can be set to correspond to any level between 0.1 V and 2.0 V rms using an externally programmed reference current.
- What is the purpose of the on-chip buffer amplifier?
The on-chip buffer amplifier can be used either as an input buffer or in an active filter configuration to reduce ac ripple and increase accuracy.
- Is the AD637JR-REEL7 protected against overload voltages?
Yes, the input circuitry is protected from overload voltages in excess of the supply levels.
- What are the temperature ranges for different grades of the AD637JR-REEL7?
The temperature ranges are 0°C to 70°C for commercial grades (J, K), -40°C to +85°C for industrial grades (A, B), and -55°C to +125°C for military grades (S).
- What external components are required for the AD637JR-REEL7?
The only external component required is a capacitor that sets the averaging period, which also determines low frequency accuracy, ripple level, and settling time.
