Agilent 5991-2778EN Methods for Characterizing and Tuning DC Inrush Current - Application Brief c20140923 [6 free download

File name 5991-2778EN Methods for Characterizing and Tuning DC Inrush Current - Application Brief c20140923 [6

Keysight Technologies Methods for Characterizing and Tuning DC Inrush Current Application Brief Introduction Inrush current or input surge current refers to the momentarily large surge current that occurs when you irst turn on power to a device. Inrush current often occurs in devices with a large amount of parallel capacitance at the input, such as DC-to-DC converters or devices with extremely low imped- ance under transient conditions, such as electric motors. Inrush current can be several times larger than the device's steady-state current. For instance, electric motors can have inrush current levels 25 times greater than their steady-state current levels. When you characterize inrush current, you either capture a high-resolution digitized proile of a device's inrush current or just capture a reliable peak current reading. The traditional method for characterizing inrush current combines a power supply, a digitizer or scope, and a current shunt or current probe. In this measurement brief, we will look at using a modern performance power supply for characterizing inrush current and compare it with the traditional method. Snapshot An automotive company is updating its test system for electronic control unit (ECU) testing. Its engineering team scrutinizes the test plan to ind ways to increase throughput and reduce test system complexity without reducing test integrity. The team identiies the inrush current measurement as a candidate for improvement. The system currently employs a power supply, a current shunt and digitizer, and switching to automate the inrush current measurement. The team decides to replace this setup with the Keysight Technologies, Inc. N7951A dynamic DC power supply. The N7951A is a fast power supply with a built-in high-resolution digitizer. N7951A provides them with a single-instrument solution that speeds up test, reduces test system complexity, and delivers higher accuracy than their old method for measuring inrush current. 03 | Keysight | Methods for Characterizing and Tuning DC Inrush Current - Application Brief Methods for Characterizing Inrush Current switch open to allow the supply to ramp-up to the set voltage level. Once that is accomplished, closing the Main reasons why characterizing inrush current is necessary switch would apply the voltage to the DUT. Even with in many test applications: the switch, problems can still surface. If the supply's transient response is poor, its voltage level will droop 1. Device