5965-8239EE.qxd 3/20/98 3:53 PM Page 1 This literature was published years prior to the establishment of Agilent Technologies as a company independent from Hewlett-Packard and describes products or services now available through Agilent. It may also refer to products/services no longer supported by Agilent. We regret any inconvenience caused by obsolete information. For the latest information on Agilent’s test and measurement products go to: www.agilent.
5965-8239EE.qxd 3/20/98 3:53 PM Page 2 Tip Use Remote Sensing to Compensate for LoadLead Effects 1 When your power supply leaves the factory, its regulation sense terminals are usually connected to the output terminals. This limits the supply’s voltage regulation abilities, even with very short leads. The longer the leads and the higher the wire gauge, the worse the regulation gets (Figure 1). Compare the output impedance of a well-regulated 10 A supply, which might have an output impedance of 0.
5965-8239EE.qxd 3/20/98 3:53 PM Page 3 Tip Charge and Discharge Batteries in Less Time 2 Using a power supply in constantcurrent mode (Figure 1) is a simple way to recharge batteries, and it also lets you achieve 100% charge levels. On the downside, this method is slow, taking as long as 14-16 hours because the charging current is only a fraction of the battery’s amp/hour rating.
5965-8239EE.qxd 3/20/98 3:53 PM Page 4 Tip Increase Safety with Remote Disable Feature 3 Remote disable offers a safe way to shut down a power supply to respond to some particular operating condition or to protect system operators (in response to a cabinet door being opened unexpectedly or someone pushing a panic button, for instance). +5 V To Microprocessor RI Masse DFI From Microprocessor Com Figure 1. Remote inhibit and discrete fault indicator schematic.
965-8239EE.qxd 3/20/98 3:53 PM Page 5 Tip Eliminate Noise from Low-Level Measurements 4 Noise in low-level measurements can come from a number of different sources, and it’s easier to eliminate noise than to filter it. Check these noise sources: 1. Power Supply Starting with a low-noise supply is naturally a great way to keep noise out of your measurements. Linear power supplies have lower common-mode noise currents, and generally operate at low frequency.
5965-8239EE.qxd 3/20/98 3:53 PM Page 6 Tip 5 Use Down Programming to Increase Test Speed Under light or no load conditions, a power supply’s output capacitor discharges slowly. If you’re using the supply as a static voltage source, this is not problematic, but when you’re making tests at varying voltage levels, slow discharge means slow tests. Down programming circuits in power supplies rapidly decrease the output voltage, reducing discharge times by hundreds of milliseconds.
5965-8239EE.qxd 3/20/98 3:53 PM Page 7 Tip Ensure Proper Power-up with Foldback Supplies 6 Foldback power supplies protect connected equipment by reducing excess current (and thus output voltage) along a foldback path. When testing foldback power supplies using an electronic load, you need to take steps to be sure the power supply starts properly.
5965-8239EE.qxd 3/20/98 3:53 PM Page 8 Tip Connect Power Supplies in Series or Parallel for Higher Output 7 Connecting two or more power supplies in series (Figure 1) provides higher voltages, but observe these precautions: Power Supply #1 • Never exceed the floating voltage rating of any of the supplies. • Never subject any of the power supplies to negative voltages. EM Power Supply #1 E1 Power Supply #1 E2 EL Program each power supply independently.
5965-8239EE.qxd 3/20/98 3:53 PM Tip 8 Page 9 Use Your Power Supply to Measure Pulsed Current To adequately specify the power source for products that exhibit pulsed and dynamic current loading (such as digital cellular phones and hard drives), you need to evaluate both the peak and dc averages current draws. You could use an oscilloscope to monitor a shunt or a current probe, but this approach raises issues with voltage drops, ground loops, common mode noise, space, and calibration.
5965-8239EE.qxd 3/20/98 3:53 PM Tip Page 10 Characterize Inrush Current with an AC Power Source/Analyzer 9 The inrush current characteristics of ac-dc switch mode power supplies vary with the turn-on phase of the voltage cycle. Usually, these power supplies have input capacitors that draw high peaks of inrush current as they charge from the rectified ac line at turn-on.
5965-8239EE.qxd 3/20/98 3:53 PM Tip 10 Page 11 Use a Power Supply to Measure DUT Supply Current Accurately measuring DUT supply currents above 10 A is beyond the range of the typical DMM in ammeter mode. You could use an external shunt and the DMM’s voltage mode, but using the power supply itself is a better solution. Many supplies include an accurate measurement system, including a shunt.
5965-8239EE.qxd 3/20/98 3:53 PM Page 12 Power products that do more and demand less. HP’s “one-box” philosophy means we pack more and more capability into the power products themselves, in some cases giving you a rack’s worth of capability in a single box. By offering more, these products demand less from you—fewer instruments, less rack space, simpler test setups, and lower cost of ownership.
5965-8239EE.qxd 3/20/98 3:53 PM Page 13 Power you can count on year after year. We’ve been a leader in the power products business for more than three decades because engineers like you know they can count on HP performance, reliability and value. Even our least-expensive dc sup- Single-output dc supplies These supplies will clean up your ATE power without cleaning out your budget.
5965-8239EE.qxd 3/20/98 3:54 PM Page 14 Power products that do more and demand less. Multiple-output dc supplies The HP 6620-series’ multiple outputs and integrated I & V readback dramatically simplify the job of system integration and maintenance. Plus, the HP 6625A, 6626A, 6628A and 6629A models offer the precision of 14-bit dual range programming and readback. Modular power system With rack space at a premium, the HP 66000 modular power system’s growing popularity is no surprise.
5965-8239EE.qxd 3/20/98 3:54 PM Page 15 AC power source/analyzers From avionics to uninterruptible power supplies, customers are demanding products that can use power efficiently while handling all kinds of ac line disturbances. To make sure your products meet these growing expectations, test them with the HP 6800-series ac power source/analyzers.
5965-8239EE.qxd 3/20/98 3:54 PM Page 16 HP DIRECT Contact Information To talk with one of our Knowledgeable sales engineers, for more information, or to place your order contact HP DIRECT.
