AD8436 Datasheet | Analog Devices

FEATURES Delivers true rms or average rectified value of ac waveform Fast settling at all input levels Accuracy: ±10 μV ± 0.25% of reading (B grade) Wide dynamic input range 100 μV rms to 3 V rms (8.5 V p-p) full-scale input range Larger inputs with external scaling Wide bandwidth: 1 MHz for - 3 d B (300 m V) 65 k Hz for additional 1% error Zero converter dc output offset No residual switching products Specified at 300 m V rms input Accurate conversion with crest factors up to 10 Low power: 300 µA typical at ±2.4 V High-Z FET separately powered input buffer RIN ≥ 1012 Ω, CIN ≤ 2 p F Precision dc output buffer Wide power supply voltage range Dual: ±2.4 V to ±18 V; single: 4.8 V to 36 V 4 mm × 4 mm LFCSP and 8 mm × 6 mm QSOP packages ESD protected Low Cost, Low Power, True RMS-to-DC Converter AD8436 FUNCTIONAL BLOCK DIAGRAM CAVG CCF VCC 100kΩ IGND 8kΩ RMS CORE 100kΩ VEE 16kΩ 10p F 10kΩ - IBUFOUT IBUFIN+ + FET OP AMP 10kΩ OGND OUT IBUFGN IBUFIN- OBUFIN+ OBUFIN- 16kΩ + - DC BUFFER 10033-001 OBUFOUT Figure 1. GENERAL DESCRIPTION The AD8436 is a new generation, translinear precision, low power, true rms-to-dc converter loaded with options. It putes a precise dc equivalent of the rms value of ac waveforms, including plex patterns such as those generated by switch mode power supplies and triacs. Its accuracy spans a wide range of input levels (see Figure 2) and temperatures. The ensured accuracy of ≤±0.5% and ≤10 µV output offset result from the latest Analog Devices, Inc., technology. The crest factor error is <0.5% for CF values between 1 and 10. The AD8436 delivers true rms results at less cost than misleading peak, averaging, or digital solutions. There is no programming expense or processor overhead to consider, and the 4 mm × 4 mm package easily fits into tight applications. On-board buffer amplifiers enable the widest range of options for any rms-to-dc converter available, regardless of cost. For minimal applications, only a single external...