ADI’s AD5755 new digital-to-analog converter, which includes ADI’s leading dc-to-dc switching converters and diagnostic features, is focusing on supporting process control systems in industrial applications which are facing growing power consumption and thermal issues that are starting to reduce equipment performance, reliability, and safety.

The data converter is a complete, multichannel control IC that incorporates four precision 16-bit DACs with programmable voltage or 4–20-mA output drivers, along with dynamic power control that works by continually sensing the load impedance and delivering the required power to the load while minimizing power loss in the rest of the system. The improved control helps to reduce self-heating and minimizes temperature elevation. ADI says the combination of features and performance benefits supports four times more channels than any other integrated converter and enables up to four times more terminals to be supported at twice the performance in a single analog I/O module.

Brendan Cronin, the product marketing manager of Analog Devices Precision Data Converters group, explains the key features and benefits of the AD5755 to Paul Buckley, EE Times Europe Power Management’s editor.


EE Times Europe: What is so special about this new multichannel 16-bit DAC?

Cronin: The AD5755 device is a complete 16-bit multi-channel data converter control IC that features Dynamic Power Control technology.  This together with the device’s high end system performance drives productivity, energy efficiency and reliability in industrial process control systems.

The device is based on ADI’s analog and power management technologies by integrating a quad precision 16-bit DAC, precision signal conditioning circuitry consisting of programmable voltage and current output drivers and Dynamic Power Control which utilizes ADI’s high efficiency DC-DC technology.
With this device we are introducing a new power management technique which we call Dynamic Power Control.

It is the first IC with Dynamic Power Control and saves on power in a system. It saves on heat generation which is critical in terms of boosting reliability and it packs more channels into the same form factor which is critical in modern plants that have to be more productive.

The savings we are achieving in terms of power consumption and heat generation we feel are very significant for this product.  This technology allows four times greater channel density and delivers twice the performance of anything else on the market.

We are calling this device a complete 16-bit 4-channel control IC and what we mean by complete here is that it is a System-on-a-Chip (SoC) type solution.  It delivers 16-bit resolution that is common throughout all of our high-end DAC family.  

The device drives a number of different metrics.  First and foremost it drives the performance which is very important in boosting productivity and efficiency in a manufacturing facility, for example, but it also optimizes power and heat generation.  The device helps to reduce power by as much as 80 percent and this is critical in terms of keeping the thermal rise to minimum and this is very important in manufacturing facilities where more and more thermal or process nodes are being deployed to boost productivity and to measure various variables within the factory.   One of the consequences of this is that heat rise rises exponentially and this is something we want to eliminate or reduce because it reduces the overall reliability of a system when you have got excess heat being generated in the module or the plant. We can offer a 75 percent reduction in thermal rise.

How we do that is with a new technique, Dynamic Power Control, which is a DC to DC switching converter technique and it makes use of all our technology that we have in our power management division of ADI.

We believe it is an industry first.  We see it as a breakthrough technology and we believe there is nothing like it on the market.  It delivers massive power and heat savings.  It senses the power that needs to be delivered to the load and only delivers the minimum required amount of power and in so doing it reduces the amount of power consumption in the rest of the system.  That is the key selling point of the technique.

The AD5755 drives 4 independent process control output channels for applications such as:

• Programmable Logic Controllers
• Actuator Control
• Distributed Control Systems
• HART and 4-20mA Networks

EE TIMES: What do you see are the key benefits of the AD5755?

Cronin: The power savings are of the order of 80 percent with this technology enabled.  The power can be reduced significantly down to under 1 W on a typical four-channel system and if you multiply that up into how many nodes are typically employed in a typical manufacturing facility which is of the order of 25,000 you can see the power consumption is very, very significant at that level.

Heat is obviously a by-product of power.  The net thermal rise is the difference between silicon junction temperature rise minus the ambient temperature.  With the control technology enabled the thermal rise is of the order of 20 degrees C which is very much within safe operating levels but without the control technology enabled the temperature rise is up to almost 100 degrees C over a long period of time.  This is quite critical because it limits the user from packing a number of thermals or channels into a given space.  It also reduces the overall reliability of the system and that is the key point.

If we take for example a fixed 30 V supply that normally supplies current into a load.  This may be quite a simple design but it is very, very inefficient when it comes to certain conditions and the worst case condition is when we have a zero Ohm load on the output which is essentially a short which can occur in normal operating environments.

The power delivered under such circumstances is 2.88 W and all that power is wasted because given the load resistance is zero Ohms no power is actually required so essentially that 2.88 W leads to heat generation which is entirely useless in the rest of the system.

For an example of how the new technology works instead of using a fixed 30 V supply we can use a 5 V fixed power supply and we use a DC-DC converter that regulates the power up to the required levels in order to deliver only the minimum amount of power which is required.  So in this case both voltage and power are dynamically adjusted depending on the condition of the load and that is essentially the key to this technology and how it works.

During a short condition which is a valid condition the typical four-channel system would have a power dissipation of 0.672 W and that is a saving of the order of 4x to the incumbent 30 V solution we described earlier.  And that is very, very significant.

EE TIMES: Can you outline some of the technology packed into the new device?

Cronin: It is a complicated chip and leverages all of ADI’s technology in terms of precision 16-bit DAC and we are both the market leaders and the technology leaders in terms data conversion technology.  

In addition it uses precision linear signal processing in terms of the voltage and current output stages which are required on the chip and also in the area of precision linear signal conditioning there is a precision voltage reference which is available to the user as a reference output pin.  Also integrated are various diagnostics which are used to monitor the condition of the system in terms of boosting operational up-time or eliminating or reducing downtime and this is very important in terms of trying to do predictive analysis of fault generation.

These are critical pieces of the signal chain that we have integrated onto this chip and the key component in all this is high efficiency Dynamic Power Control technology which is implemented using our latest DC-DC converter technology which is highly efficient technology which was developed by our power management design group in California.

There is also on-chip diagnostics which focuses on fault analysis which is very important for all our customers.  They want to be able to predict when a fault will occur but as soon as it does they want to have some form of trend analysis to try and predict when a fault will occur in the system.

There is an on-chip reference of 5ppm/degree C max which is one of the more accurate references on a single piece of silicon of this size on the market.  The IC is qualified by ADI to work over the extended range of -40 degrees C and +105 degrees C.

This technology supports more accurate control in less space because it is an integrated function.  It reduces energy consumption which saves on heat generation which helps boosts reliability and it also reduces the overall power saving within the plant which can be very significant in modern power plants or chemical plants which have multiple nodes deployed across a single machine, for example, and that can be multiplied up as you have multiple machines in a given factory.  

The combination enables unprecedented system efficiency.  This is the key trend in the industry.  They are looking to boost productivity, get more out of the same equipment.

More processing is required which is driving efficiency in the power plant and there is also a trend in the industry to greener solutions that will reduce power consumption and this chip will enable our customers to deliver more energy efficient products.  That enables differentiation for our end customers and that is certainly something they have told us that this technology will enable them to do.  Cost cannot be underestimated. The reduction in overall cost is also key trend in the industry.

This chip with its level of integration, its full channel specification (which saves user calibration time) all helps to reduce the overall cost of the system and because the chip requires less power to drive the system that saves on energy costs as well.

The four-channel system enables higher thermal density and certainly the savings on power enables more thermals to be packed into the same form factor for the customer.  So, for example, our customers would very often have eight-channel systems which would be multiplied up into racks which could be thousands of channels for a specific machine.  This solution will allow more channels to be packed into the same system but also more modules to be packed into the control of the machine.

We are offering a full channel specification and this is pretty unique in the industry.  There is no competing product on the market that would have such an extensive channel specification.   Our customers and OEMs like to look at a piece of silicon and want to know the full channel performance and instead of computing all the errors from the data converter, signal conditioning circuitry or the power management indicator they are really looking for a lumped measurement of the total error and this chip certainly delivers that.

EE TIMES: Calibration seems to be a major headache for the process industry. 
How does this device cope with this issue?

Cronin: When we talked to customers over the years about defining and solving their problems one of the things they certainly highlighted as well as power and heat generation was the fact that they had to perform multiple calibrations in order to eliminate drift effects.  Also calibrations had to be performed quite regularly at the customer site as part of maintenance procedures.  Really our customers were looking for a solution to this problem.  They were looking for a single component that was more accurate but was also less susceptible to drift both in terms of temperature but also perhaps more importantly in terms of time.

This is where our full channel specification comes in.  ADI will essentially guarantee the specifications of the IC which will enable a better channel spec at the module level but we guarantee those specifications over time and we do that with accelerated lifetime testing within the factory and that certainly adds value to our customers in terms of reducing costs, calibration and overheads.

EE TIMES: Are you offering an evaluation system?

Cronin: We provide a fully functional evaluation system.  This is important for customers because it allows them to easily design in faults to check them.  It allows them to characterise their design and do the functional testing and age testing of the IC before they embed it or implement it on their system.  That reduces the overall time-to-market for our end customers so that is an important service that we provide and we also offer fully assigned resources for application support.  As you can imagine with this level of integration there are a lot of questions from the end user engineers and we have dedicated application staff to do deal with those questions as they come in.

EE TIMES: What primary applications you looking to address?

Cronin: The primary market this product is targeting is the programmable logic controller (PLC) market. That will be the largest for sure but it is also targeting the Distributed Control Systems (DCS) market. and any Hart 4-20mA communications network which is used extensively throughout factory automation.

This chip has the ability to connect in HART protocol signals which is modulated onto the current loop in terms of doing better diagnostics and more trend analysis.  It was important that we included that function for our customers.

EE Times: How long has ADI been developing this new solution?

Cronin: My data converter design group in Limerick, Ireland, has worked extensively with our Power Management group in California to develop a new piece of IP which has very high performance coupled with its very small size.  This chip has probably been in development for 18 months.    

EE TIMES: So in summary what would you say are the three key selling points of the new DAC?

Cronin: For the first point we have to look at Dynamic Power Control and the savings both from a power and a thermal point of view.  The thermal issues are such a problem for customers to solve and its amazing the amount of trickery that they do in their products in order to keep temperature down.  They use lots of air cooling and water cooling systems to regulate the heat which are very expensive to implement and very expensive to maintain. So the control of heat is certainly the biggest challenge for our customers today.  

For the second point it enables more channels to be packed into a given module and enables our customers to deploy more thermals in their system.  So we are talking a greater channel density.

The third selling point would be the device’s price to performance benefits compared with anything else on the market.

EE TIMES: Is the available AD5755 now?

Cronin: The product is available right now and we have already delivered it to a number of the key industrial OEMs worldwide.  In the part will be available for a production run in October of this year.

EE TIMES: How do you think you will be able to improve on this device in the future?

Cronin: We already have some ideas on how we can improve this chip.  We are certainly looking at greater ways to improve efficiency and maybe packing more channels in there and I think that is the key trend in the industry.  And we will be following the key trends.

Related links and articles:

Multichannel data converter offers dynamic power control for first time

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