Understanding Emerging Measurement Requirements for Battery-Powered Devices
June 21, 2010
The trend in the electronics market has been to make an increasing number of devices integrated and portable. As a result, smartphones, eBook readers, MP3 players, and medical devices with multiple functions and features have emerged. Aside from functionality and features, battery runtime has become the single-most critical factor to product differentiation and customer satisfaction.
In order to optimize power consumption and maximize battery life, engineers typically utilize advanced power-management schemes that rapidly turn on/off subcircuits as necessary, creating dynamic current consumption typically from uA to A. Unfortunately, traditional test instruments are not well suited for this type of measurement requirement. Digital multimeters (DMMs) can accurately measure over the dynamic range, for example, but they cannot measure rapid changes over time. Oscilloscopes can measure rapid changes over time, but due to the need for a current probe or shunt they lack accuracy (not enough vertical resolution) and dynamic range.
The inability of traditional test instruments to make dynamic current measurements has, in many cases, led designers of battery-powered devices to source/measure units (SMUs). While the SMUs currently on the market are well known for their high accuracy in both sourcing and measurement, and may seem like a logical choice (especially for device parametric test of static loads), this is not always the case. They are not ideal for dealing with the dynamic conditions present when sourcing power to, and measuring the power consumption of, a battery-powered device or one of its components. Conventional SMUs lack the voltage transient response necessary to hold a stable output. And, despite the fact that they offer very accurate measurements in a fixed range, they lack the ability to change ranges quickly and without disrupting the measurements.
Parametric test is the process of discovering, or characterizing, a device’s parameters by providing a stimulus and measuring the reaction to the stimulus. The device is typically a single passive component, a semiconductor (diode or transistor) or a wafer. In some cases, the device can also be an integrated circuit (IC). Parametric test requires extremely high accuracy and 4-quadrant sourcing—something that most SMUs on the market today are specifically designed for and are therefore well suited to do.
Functional test involves testing the operational behavior of a device against what the device was designed to do. The device can be an IC, a chipset or a finished product designed to perform a specific function. Functional test requires high accuracy, 2-quadrant operation, speed, and flexibility to test many different types of devices. Battery drain analysis is one form of functional test.
The Agilent N6781A and N6782A 2-Quadrant Source/Measure Units for battery drain analysis and functional test are designed to meet the test needs of engineers designing battery-powered devices. Unlike traditional SMUs, which were designed specifically for device parametric test, the Agilent N6781A and N6782A 2-Quadrant SMUs were specifically designed to meet the unique test challenges of battery drain analysis and functional test. Features such as stable output voltage and seamless measurement ranging make the N6781A and N6782A SMUs ideally suited for battery-powered device design and test.
|Press Release:||Agilent N6780 Series Source/Measure Units (SMUs) for the N6700 Series Modular Power System (2010-June-21)|
Janet Smith, Americas
Sarah Calnan, Europe
Iris Ng, Asia