Features and Benefits
- 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
The AD8436 is a new generation, translinear precision, low power, true rms-to-dc converter loaded with options. It computes a precise dc equivalent of the rms value of ac waveforms, including complex 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 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 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 input range even lower. The low power, precision input buffer makes the AD8436 attractive for use in portable multi-meters and other battery-powered applications.
The precision dc output buffer minimizes errors when driving low impedance loads with extremely low offset voltages, thanks to internal bias current cancellation. Unlike digital solutions, the AD8436 has no switching circuitry limiting performance at high or low amplitudes. A usable response of <100 μV and >3 V extends the dynamic range with no external scaling, accommodating demanding low level signal conditions and allowing ample overrange without clipping.
The AD8436 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 are available in a 20-lead QSOP package. The operating temperature ranges are −40°C to 125°C for A and B grades and 0°C to 70°C for J grade.
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
The AD8436 evaluation board is fully assembled, tested and ready to use after the power and signal sources are connected. The AD8436-EVALZ offers many options, without sacrificing simplicity. The board is tested and shipped with a 10 μF averaging capacitor (CAVG), 3.3 μF low-pass filter capacitor (CLPF) and a 0.1 μF (CCF) capacitor to optimize crest factor performance. Please see AD8436 data sheet available on-line for complete details.
Tools & Simulations
ADIsimPE, which is powered by SIMetrix/SIMPLIS, is a circuit simulation suite optimized for the design and development of analog and mixed signal circuits. SIMetrix mode is ideal for the simulation of general non-switching circuits. It provides full Pspice compatibility for use with industry-standard SPICE models. SIMPLIS (SIMulation Piecewise-Linear System) mode simulates the operation of switching circuits with vastly improved robustness, speed, and accuracy compared to standard SPICE. It is particularly useful for switching power supply, PLLs, and ADC/DAC applications.
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.