Rohde & Schwarz DC Power Supplies

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 Rohde & Schwarz (R&S) DC power supplies operate primarily as programmable, high-efficiency, switch-mode power supplies (SMPS) or hybrid designs, featuring Constant Voltage (CV), Constant Current (CC), and optional Constant Resistance (CR) modes. They convert line voltage by rectifying, chopping, and filtering, providing stable, precise voltage/current to devices under test (DUT) with low ripple, often using linear regulators to further refine output, notes Rohde & Schwarz.

Core Working Principles

• Operating Modes (CV/CC):
  • Constant Voltage (CV): The unit maintains a fixed output voltage; current varies based on the load. If the current exceeds the user-set limit, the unit automatically switches to CC mode to protect the device.
  • Constant Current (CC): The power supply acts as a current source, limiting the output current to a preset value while adjusting the voltage to match the load requirements.
  • Constant Resistance (CR): The unit behaves like a programmable resistor, useful for simulating battery discharge, as seen in this document from Farnell.

• Power Conversion Technology:
  • Switch-Mode (SMPS) (e.g., R&S NGP800): Used in high-power series like the R&S®NGP800, these supplies chop DC voltage at high frequencies using switching transistors. Regulation is achieved by adjusting the duty cycle (Pulse Width Modulation), which offers high efficiency and a compact footprint.
  • Linear/Hybrid Design (e.g., R&S NGE100B, HMP): Combines a transformer with switching regulators for efficiency, followed by a linear stage to minimize noise and ripple at the output.

• Functionality & Features:

• Programmability: Users can set voltage, current, and Protection limits (OVP/OCP).
• Arbitrary (EasyArb): The capability to program sequences of different voltage/current levels over time.
• Tracking & Parallel/Series: Channels can be linked for synchronized operation or combined for higher voltage/current.
• Sink Operation: Some models can operate as an electronic load (sinking current), detailed in this document from Farnell.