The AD737 is a low-power, precision, single-chip true-rms DC converter. It is laser-tuned with a maximum error of ±0.2 mV ± 0.3% of the reading when using a sine wave input. Additionally, it can measure a wide range of input waveforms with high accuracy, including variable duty cycle pulses and three-terminal triac (phase) controlled sine waves. The converter's low cost and small size make it suitable for upgrading the performance of non-RMS precision rectifiers in many applications. Compared to these circuits, the AD737 offers higher accuracy at the same or lower cost.
The AD737 can calculate RMS values for both AC and DC input voltages. When an external capacitor is added, it can also work in AC coupling mode. In this mode, the AD737 can resolve input signal levels of 100 μV rms or less, even in the presence of temperature or supply voltage fluctuations. For input waveforms with a crest factor of 1 to 3, high accuracy is also maintained. In addition, at the 200 mV full-scale input level, the crest factor can be as high as 5 (the measurement introduces only an additional error of 2.5%).
The AD737 does not have an output buffer amplifier, which greatly reduces DC offset error at the output, making it highly compatible with high input impedance ADCs.
It has a supply current of only 160 μA and is optimized for portable multimeters and other battery-powered applications. In power-down mode, the typical standby supply current is 25 μA.
The AD737 provides both high impedance (1012 Ω) and low impedance inputs. The high-impedance FET input can be interfaced directly with the high-source impedance input attenuator, and the low-impedance (8 kΩ) input can operate at a minimum supply voltage of ±2.5 V while accepting a root mean square voltage of 0.9 V. The two inputs can be single-ended or differentially configured.
The AD737 achieves a 1% reading error bandwidth with an error bandwidth of more than 10 kHz and a power consumption of only 0.72 mW for an input range of 20 mV rms to 200 mV rms.
The AD737 is divided into two grades based on performance. The AD737J and AD737K have an operating temperature range of 0°C to 70°C commercial temperature range. The AD737JR-5 has been tested at a ±2.5 V DC supply voltage. The AD737A has an operating temperature range of −40°C to +85°C industrial temperature range. The AD737 is available in two low-cost 8-pin packages: PDIP and SOIC_N.
Product features:
1.无论其波形如何，可计算一个信号的平均整流、绝对、或真均方根值。
2.AD737执行真均方根测量只需要一个外部元件：一个均值电容。
3.AD737的待机功耗仅125 μW，适合电池供电应用。