Chapter 3 -- Instrument Circuitry--Reference 3000 Schematic/Block Diagrams
3 - 8
Figure 3-6
DC-DC Power Conversion
Notes for Figure 3-6:
• Note the ground isolation between the input power and the Reference 3000 circuitry. The Reference
3000 chassis is connected to the Floating Instrument Ground. Transformers and isolators are the only
components connected between the grounds.
• The 300 kHz power supply sync signal is derived from the same clock used to control data acquisition.
Data points taken at an integer multiple of 3.333 µSec/point will be synchronized with the power
supply, minimizing the effect of power supply noise on the data.
• Additional circuitry that is not shown protects the Reference 3000 against ESD (electrostatic discharge)
and electrical surges. Note that the Reference 3000 is also protected against damage if an incorrect
polarity power input is connected to the unit.
• The incoming DC voltage must be between 22 and 26 volts. With inputs below 22 volts, the PWM
(Pulse Width Modulator) may be unable to regulate the supply. Above 26 volts, the PWM may not
start-up.
WARNING
Do not use a DC power source other than the AC adapter model provided with your
Reference 3000. Other replacements may void the performance and/or safety
characteristics of the Reference 3000.
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