How Much Current Will the 54xx Arbitrary Waveform Generators Source?Hardware: Signal Sources (AWG/FG/AO)>>Arbitrary Waveform and Function Generators
Problem: The specifications for the 54xx series of Arbitrary Waveform Generators show an output voltage of either +/-1 V into 50ohms [40mA), +/-5 V into 50ohms (100mA) or +/-6 V into 50 ohms (120mA). How much current can I expect if I'm driving a lower impedance load? What voltage can I expect for load impedances greater than 50 ohms? Solution: First, the open circuit voltage of the particular Arbitrary Waveform Generator (ARB) must be known. 5404 = +/-2 V 5401,5411,5431 = +/-10 V 5412, 5421, 5422, 5441 = +/-12 V The analog output of the ARB can be viewed as a +/-2 V,+/-10 V, or +/-12 V source in series with a 50 ohm or 75 ohm resistance, depending on the software setting. So, for a load less than 50 ohms, more than 40mA, 100mA, or 120mA is available respectively. You can use simple circuit equations to determine the maximum voltage/current available for a given load.  Vout = ± [ RL / ( RL + RO ) ] × Voc where Vout is the maximum output voltage level, Voc is the open circuit voltage of the ARB as listed above, RL is the load impedance in ohms and RO is the output impedance on the ARB. For example, with the 5411 driving a 600 ohm load, the maximum voltage swing is approximately +/- [ 600 / ( 600 + 50 ) ] x 10V = +/-9.2 V. In theory the 5411 should deliver 200mA when short circuited. In practice, the maximum current available is slightly lower than the calculated value for low impedance loads. Keep in mind that the ARBs were not designed to drive loads less than 50 ohms. Related Links: Attachments: 
Report Date: 08/28/2003 Last Updated: 07/02/2007 Document ID: 30RAFQ6W |
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