The AD8436BRQZ-R7 is a new generation, translinear precision, lowpower, true rms-to-dc converter loaded with options. It computes a precise dc equivalent of the rms value of ac waveforms, includingcomplex patterns such as those generated by switch mode power supplies and triacs. Its accuracy spans a wide range of input levels 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 valuesbetween 1 and 10.
The AD8436BRQZ-R7 delivers true rms results at less cost than misleading peak, averaging, or digital solutions. There is no programmingexpense or processor overhead to consider, and the 4 mm × 4 mmpackage easily fits into tight applications. On-board bufferamplifiers enable the widest range of options for any rms-to-dc converter available, regardless of cost. For minimal applications, only a single external averaging capacitor is required. The built-in high impedance FET buffer provides an interface for external attenuators, frequency compensation, or driving low impedance loads. A matched pair of internal resistors enables an easily configurable gain-of-two or more, extending the usable inputrange even lower. The low power, precision input buffer makes the AD8436BRQZ-R7 attractive for use in portable multi-meters and other battery-powered applications.
The precision dc output buffer minimizes errors when drivinglow impedance loads with extremely low offset voltages, thanks to internal bias current cancellation. Unlike digital solutions, the AD8436BRQZ-R7 has no switching circuitry limiting performance at high or low amplitudes. A usable response of <100 μVand >3 V extends the dynamic range with no external scaling,accommodating demanding low level signal conditions andallowing ample overrange without clipping.
The AD8436BRQZ-R7 operates from single or dual supplies of ±2.4 V(4.8 V) to ±18 V (36 V). A and J grades are available in a compact 4 mm × 4 mm, 20-lead chip-scale package; A and B grades areavailable in a 20-lead QSOP package. The operating temperatureranges are −40°C to 125°C for A and B grades and 0°C to 70°Cfor J grade.
Feature
- 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 dB (300 mV)
- 65 kHz for additional 1% error
- Zero converter dc output offset
- No residual switching products
- Specified at 300 mV 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 pF
- 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
(Picture: Pinout)
