AD536AJH Analog Devices

AD536AJH Analog Devices

The AD536A is a fully integrated monolithic circuit designed for true rms-to-dc conversion. It delivers performance that is either comparable to or exceeds that of hybrid or modular units that are significantly more expensive. The AD536A calculates the true rms value of any intricate input waveform that includes both ac and dc components. A crest factor compensation mechanism enables measurements with an error margin of 1% at crest factors reaching up to 7.

The device’s extensive bandwidth enhances its measurement capabilities to 300 kHz, maintaining less than 3 dB errors for signal levels above 100 mV. A notable feature of the AD536A, which was not previously found in rms converters, is the auxiliary dB output pin. This pin outputs the logarithm of the rms signal, facilitating dB conversion with a dynamic range of 60 dB.

By utilizing an externally supplied reference current, the 0 dB level can be easily adjusted to align with any input level ranging from 0.1 V to 2 V rms. The AD536A is laser-trimmed to reduce input and output offset voltage, enhance positive and negative waveform symmetry (dc reversal error), and ensure full-scale accuracy at 7 V rms. Consequently, no external adjustments are necessary to meet the specified unit accuracy.

Both the input and output pins are thoroughly protected. The input circuitry is capable of handling overload voltages that exceed the supply levels. A loss of supply voltage while the input is connected to external circuitry does not lead to device failure.

Additionally, the output is safeguarded against short circuits. FUNCTIONAL BLOCK DIAGRAM dB BUFFER IN VIN 25kΩ 80kΩ 25kΩ CAV +VS –VS +VS COM AD536A RL IOUT BUFFER OUT CURRENT MIRROR SQUARER/ DIVIDER ABSOLUTE VALUE 00504-001 + BUF Figure 1. The AD536A is offered in two accuracy grades (J and K) suitable for commercial temperature ranges (0°C to 70°C) and one grade (S) designed for the extended range of −55°C to +125°C.

The AD536AK provides a maximum total error of ±2 mV ± 0.2% of the reading, whereas the AD536AJ and AD536AS exhibit maximum errors of ±5 mV ± 0.5% of the reading. All three models are offered in a hermetically sealed 14-lead DIP or a 10-pin TO-100 metal header package.

Additionally, the AD536AS is available in a 20-terminal leadless hermetically sealed ceramic chip carrier. The AD536A calculates the true root-mean-square level of a complex ac (or ac plus dc) input signal and delivers an equivalent dc output level. The true rms value of a waveform is a more significant measure than the average rectified value, as it directly correlates to the power of the signal.

Furthermore, the rms value of a statistical signal is also associated with its standard deviation. To achieve fully specified accuracy in measurements, an external capacitor is necessary. The capacitance value of this capacitor influences the low frequency ac accuracy, ripple amplitude, and settling time. The AD536A functions effectively with either split supplies or a single supply, accommodating total supply levels ranging from 5 V to 36 V. With a quiescent supply current of 1 mA, the device is ideally suited for a diverse range of remote controllers and battery-operated instruments.