Q4: What is the ESD rating of the AD4170-4?

HBM Model Pass Level: 4.0 kV, FICDM Model Pass Level: 1.25 kV.

Q11: What is the equation when calculating temperature using the Internal Temperature Sensor?

For the AD4170-4, the sensitivity of the internal temperature sensor is 477 µV/K approximately when VREF = 2.5V. Bipolar coding is used when reading the internal temperature sensor. The formula to convert the ADC output code to a temperature when operating in bipolar mode is: Temp (°C) = (Conversion (μV) / Sensitivity (μV/K)) – 273.15 Subtract 5°C from the temperature result.

Q10: How to measure Output Data Rate (ODR) when multiple channels are enabled (all use the same filter type and same ODR setting)?

When continuously converting on a single channel, the very first conversion requires a time of Tsettle first conversion (settling time), and the subsequent conversions take a time equal to 1/(programmed ODR). When converting multiple channels, the conversion time for the first enabled channel again equals Tsettle first conversion (settling time) since the filter type and FS value is the same as used for the single channel case above. The conversion time for subsequent channels is now close or similar to Tsettle first conversion (settling time). The conversion time for subsequent channels takes longer than 1/(programmed ODR) because each time that the channel is changed (when sequencing between channels), the ADC needs to gather samples relevant to the new analog input to generate the conversion result, thus, completing the settling time needed.

Q9: Is an IBIS model available for the AD4170-4?

There is an IBIS model available for the AD4170-4 that can be downloaded at the following link: https://www.analog.com/en/license/ibis-models.html?mediaPath=/media/en/simulation-models/ibis-models/ad4170-4.ibs.zip&modelType=ibis-models

Q8: I am not designing a system for functional safety. Are the diagnostics still useful?

The on-chip diagnostics are useful in any system, even an application where functional safety is not important. The on-chip diagnostics allow the user to verify the circuit connections, the blocks within the ADC such as the PGA, reference and ADC itself can be monitored to ensure that all blocks are functioning correctly. Since the on-chip registers can be monitored, the user can be confident that no register changes have occurred. Finally, the serial interface has a lot of diagnostics such as read/write checks, any invalid read/write operations are ignored. On other ADCs, the ADC does not ignore invalid commands which can lead to register corruption or even the serial interface becoming asynchronous. The AD4170-4’s diagnostics give the user confidence that only correct read/write operations are sent/received by the AD4170-4, that on-chip registers are not corrupted, and that conversions are invalid. Any errors for these conditions will be indicated by the Error bits.

Q7: What is the data output coding format used in AD4170-4?

On the AD4170-4, two different coding options exist: unipolar and bipolar coding. Unipolar coding is used to represent positive voltages only, and bipolar coding can be used to represent both negative and positive differential voltages applied to the analog inputs of the ADC. For the ADC operating in unipolar mode, the input range to the ADC is from 0V to Full scale, where the full-scale value is equal to VREF/Gain (reference input voltage/PGA Gain setting). The output coding is straight binary which means that a zero differential input voltage applied to the analog inputs results in an output code of 00...00 (0x000000) a midscale voltage (VREF/(2*Gain)) applied to the analog inputs results in an output code of 100...000 (0x800000) a full-scale input voltage (VREF/Gain) results in an output code of 111...111. (0xFFFFFF) When the ADC is operated in bipolar mode, the input range is from negative Full Scale (-FS) to positive Full Scale (+FS) where Full Scale (FS) equals VREF/Gain (reference input voltage/selected PGA gain). The output coding for bipolar operation is two’s complement with a negative full-scale voltage applied to the analog inputs results in an output code of 100...00 (0x800000) a zero differential input voltage applied to the analog inputs results in an output of 00...000 (0x000000) a positive full-scale input voltage applied to the analog inputs results in an output code of 011...111 (0x7FFFFF)

Q6: Are there tools or software drivers available for the AD4170-4?

ACE software is available which includes demo modes to get customers up and running with just the click of a button. With the embedded Active Functional Model (AFM) of the AD4170-4 integrated into ACE, this allows the customer to evaluate the part without having hardware. The AFM gives timing diagrams, filter profile information, noise information and more to help the customer understand the timing, operation and performance for the configuration implemented and will help with the software/firmware development. Software code also available, https://bitbucket.analog.com/projects/PCTS/repos/precision-converters-firmware/browse/projects/ad4170_iio?at=refs%2Fheads%2Fdevelop .

Q5: Can I use a single AIN pin as analog input pin and shared this pin as output of Internal Excitation Current Source (IOUT) pin?

Yes, that should work and the number of AIN pins per sensor is minimized. However, sharing pins will add error to the overall conversion as there will be a voltage drop across the R of the RC anti-aliasing filter/EMC filtering which is in series with the resistive sensor, thus limited R values can be used. For optimum EMC/anti-aliasing performance, it is best practice to enable IOUT on a dedicated pin and apply the current to the resistive sensor outside of the AIN input filters. In this case, only leakage current goes through the R value of the external filter so the impact of the R value on overall accuracy is minimized. This implementation uses one extra AIN pin versus the shared implementation.

Q3: There are a number of filter options for the AD4170-4. Which one should I use?

The AD4170-4 has several filter options; Sinc5 + AVg, Sinc3, Sinc5, Post (FIR) Filter, Wideband FIR Filter, and Programmable Wideband FIR Filter. The filter type selection affects the rms noise, the 50/60 Hz rejection, the settling time, stopband attenuation and AC performance. So, a trade-off is needed among the different parameters. The Sinc filters are good for DC inputs, designs requiring low latency, and multiplexed applications. With the Sinc3 and Sinc5 filters, the noise performance is similar at the lower output data rates. Hence, the AD4170-4 provides the Sinc3 filter only at the low output data rates. At the higher output data rates, the higher order Sinc filter gives better noise performance. So, the Sinc5 filter is selectable at these higher output data rates to reject the noise more effectively. These filters can be selected on a per channel basis when using the sequencer and can also be programmed to provide simultaneous 50 Hz and 60 Hz rejection. The FIR filter is suitable for AC inputs. The FIR filter has low pass-band ripple, quick roll-off and good stop-band attenuation. Therefore, it is the optimum choice for AC inputs. The FIR filter has a long settling time. Note that the FIR filter can be used when a single channel only is enabled. It cannot be used when the sequencer is used.

Q2: What are the target markets and applications for the AD4170-4?

The AD4170-4 can support various end markets (INA, INS, Healthcare) and applications such as Industrial Process Control, Temperature Measurement, Pressure Measurement, Weigh scale, Scientific Measurement, Chromatography, Electrical Test and Measurement, Seismic, Energy Exploration, High Accuracy and Precision Medical Instrumentation. With the AD4170-4, a platform solution offers significant advantages such as simplifying the Bill of Materials (BOM), which lowers costs and reduces board size. Instead of purchasing multiple types of ADCs for different systems, the customer only needs one device to support many end systems. This approach facilitates technology reuse, enabling insights gained from one project to benefit subsequent ones. As a result, design time and time to market are both reduced.

Q1: What is the value add of the AD4170-4?

The AD4170-4 SD ADC has been developed to bridge the performance gaps between precision and medium bandwidth SD ADCs, capable of supporting both AC and DC measurements. It embodies more speed, lower noise, more intelligence such as a smart sequencer and per channel configuration, and more diagnostics – a system on a chip with the ability to excite and measure signals from sensors in the bandwidth from DC to 50 kHz, providing one complete solution enabling platform designs to accommodate sensor clusters and sensor fusion.