| Battery run time is one of the easiest product characteristics for an end user to recognise and we can all relate to the anxiety caused when our mobile phone's battery is low. |  |
The design engineer's task is therefore to deliver exceptional battery life for the device in question, but to do so they must be in possession of the tools to measure and analyse dynamic current drain from sub-microamps to amps. Charlie McClelland, Keysight Technologies product specialist at Aspen Electronics, review the Keysight Dynamic Current Drain Solution.
The success of the wireless revolution is visible in the number of devices we use every day - smartphones, tablets, e-readers, GPS units, wearable patient monitors, heart-rate monitors and many more. Some attribute this success to the long awaited convergence of highly integrated technology, wide bandwidths, application rich content and attractive pricing. Of course, the insatiable demand for anytime, anywhere access leads to end user expectations that increase the pressure on product designers. As an example, visit any product review page and one of the biggest issues, or opportunities becomes clear - battery life.
The power challenge stems from two shared issues. One is the need to use power from a finite source - usually a battery or a low cost, low power DC bus. The other is long periods of standby operation between bursts of intense RF activity. The resulting current drain is pulsed with extremely high peak current, incredibly low standby current with resulting low duty cycle and low average values. to be able to accurately predict the battery life (discharge rate) in the device you are designing is therefore very important, but very challenging using many of today's existing tools. For example, when traditional Ammeter technology is used to measure current, the act of inserting it changes the characteristics of the circuit - so the results are false and meaningless.
Power Measurement - To maximise battery life, you may use a variety of advanced power management techniques. For example, sub-circuits can be rapidly turned on and off to help reduce overall power consumption. As the device transitions between different operating states, this creates dynamic current consumption that ranges from sub-micro-amperes to amperes. Measuring these dynamic changes is essential to understanding power consumption and battery life. However, handling a 1,000,000 to 1 ratio between minimum and maximum current levels is not possible with typical tools - digital multimeters (DMMs), oscilloscopes, current probes, conventional source/measure units (SMUs) or multiple shunt resistors. With today's million-to-one dynamic current ratios, these typical solutions fall short in many ways and can result in poor results, inaccurate understanding and daily frustration.
To overcome these issues, Keysight Technologies have created a solution. It looks nothing like a conventional "meter", but it's purpose built solution that provides high accuracy and flexible measurement capabilities, including the 1,000,000 to one measurement ratio and measuring live with the DUT operating normally. It is made up of three main elements - the N6705B DC Power Analyser, either the N6781A and N6785A 2-Quadrant SMU and the 14585A Control and Analysis Software. Serving as both a source (power supply) and measurement device, the N6781A and N6785A modules provide stable DC output voltage, programmable output resistance and an auxiliary digital voltage meter (DVM) to provide a solution. Keysight's N6780 Series SMU hardware lets you visualise current drain from nA to A in one pass and one picture, unlocking insights to deliver improvement battery life. they can provide exact, controllable amounts of power to accurately emulate a battery in any of it's three states - sleep, standby and transmit/on.
The N6705B DC Power Analyser has the ability to accept up to four DC power modules and provides productivity gains in the sourcing and measuring of DC voltage and current to and from a DUT. It does this by integrating advanced power supplies with DMM, scope, arb and data logger features. As a result, the N6705B eliminates the need to first gather multiple pieces of test equipment and then create complex test set-ups, including current probes and shunts, and perform often complex calculations, measuring current into a DUT.
N6781A and N6785A 2-Quadrant SMUs create a totally integrated solution that includes DC sourcing and built-in measurement capabilities that simplify the process of battery drain analyss for devices up to 20W. Key features include seamless measurement ranging, programmable output resistance and ana auxiliary DVM. Their fast recovery times and glitch-free operation when powering dynamic loads helps ensure proper operation of the DUT.
In battery emulator mode, the source is programmable in terms of both DC level and output resistance to more accurately emulate a battery. The ability to operate as a CC or CV load, in static and dynamic operation, is used to create battery charge and discharge profiles. For stress testing, and more, the N6781A and N6785A help you create custom DC power waveforms such as DC bias supply transients and disturbances.
When used with the 14585A software, the N6781A and N6785A becomes an even more powerful solution for battery drain analysis. through a familiar PC interface, the 14585A software lets you control the advanced capabilities of the N6705B/N6781A and N6785A. It also helps analyse data acquired with the N6705B/N6781A and N6785A. Capabilities include waveform capture, zoom in on areas of interest, replay back to DUT, long term data logging and CCDF statistical analysis.
Summary - The dynamic current drain solution can be easily configured, helping the operator quickly set-up the system for specific operating conditions. The patented "seamless measurement" capability enables measurement and visualisation of current drain in new and informative ways. A single sweep provides accurate measurements that range from sub-micro-amps to amps. In ammeter mode, a battery can be connected to the DUT to simultaneously log the current drain profile, along with battery voltage values, with no shunt burden voltage.
The power challenge stems from two shared issues. One is the need to use power from a finite source - usually a battery or a low cost, low power DC bus. The other is long periods of standby operation between bursts of intense RF activity. The resulting current drain is pulsed with extremely high peak current, incredibly low standby current with resulting low duty cycle and low average values. to be able to accurately predict the battery life (discharge rate) in the device you are designing is therefore very important, but very challenging using many of today's existing tools. For example, when traditional Ammeter technology is used to measure current, the act of inserting it changes the characteristics of the circuit - so the results are false and meaningless.
Power Measurement - To maximise battery life, you may use a variety of advanced power management techniques. For example, sub-circuits can be rapidly turned on and off to help reduce overall power consumption. As the device transitions between different operating states, this creates dynamic current consumption that ranges from sub-micro-amperes to amperes. Measuring these dynamic changes is essential to understanding power consumption and battery life. However, handling a 1,000,000 to 1 ratio between minimum and maximum current levels is not possible with typical tools - digital multimeters (DMMs), oscilloscopes, current probes, conventional source/measure units (SMUs) or multiple shunt resistors. With today's million-to-one dynamic current ratios, these typical solutions fall short in many ways and can result in poor results, inaccurate understanding and daily frustration.
To overcome these issues, Keysight Technologies have created a solution. It looks nothing like a conventional "meter", but it's purpose built solution that provides high accuracy and flexible measurement capabilities, including the 1,000,000 to one measurement ratio and measuring live with the DUT operating normally. It is made up of three main elements - the N6705B DC Power Analyser, either the N6781A and N6785A 2-Quadrant SMU and the 14585A Control and Analysis Software. Serving as both a source (power supply) and measurement device, the N6781A and N6785A modules provide stable DC output voltage, programmable output resistance and an auxiliary digital voltage meter (DVM) to provide a solution. Keysight's N6780 Series SMU hardware lets you visualise current drain from nA to A in one pass and one picture, unlocking insights to deliver improvement battery life. they can provide exact, controllable amounts of power to accurately emulate a battery in any of it's three states - sleep, standby and transmit/on.
The N6705B DC Power Analyser has the ability to accept up to four DC power modules and provides productivity gains in the sourcing and measuring of DC voltage and current to and from a DUT. It does this by integrating advanced power supplies with DMM, scope, arb and data logger features. As a result, the N6705B eliminates the need to first gather multiple pieces of test equipment and then create complex test set-ups, including current probes and shunts, and perform often complex calculations, measuring current into a DUT.
N6781A and N6785A 2-Quadrant SMUs create a totally integrated solution that includes DC sourcing and built-in measurement capabilities that simplify the process of battery drain analyss for devices up to 20W. Key features include seamless measurement ranging, programmable output resistance and ana auxiliary DVM. Their fast recovery times and glitch-free operation when powering dynamic loads helps ensure proper operation of the DUT.
In battery emulator mode, the source is programmable in terms of both DC level and output resistance to more accurately emulate a battery. The ability to operate as a CC or CV load, in static and dynamic operation, is used to create battery charge and discharge profiles. For stress testing, and more, the N6781A and N6785A help you create custom DC power waveforms such as DC bias supply transients and disturbances.
When used with the 14585A software, the N6781A and N6785A becomes an even more powerful solution for battery drain analysis. through a familiar PC interface, the 14585A software lets you control the advanced capabilities of the N6705B/N6781A and N6785A. It also helps analyse data acquired with the N6705B/N6781A and N6785A. Capabilities include waveform capture, zoom in on areas of interest, replay back to DUT, long term data logging and CCDF statistical analysis.
Summary - The dynamic current drain solution can be easily configured, helping the operator quickly set-up the system for specific operating conditions. The patented "seamless measurement" capability enables measurement and visualisation of current drain in new and informative ways. A single sweep provides accurate measurements that range from sub-micro-amps to amps. In ammeter mode, a battery can be connected to the DUT to simultaneously log the current drain profile, along with battery voltage values, with no shunt burden voltage.