Improving the measurement accuracy of DC power supply requires comprehensive optimization from multiple dimensions such as calibration methods, environmental control, and operating standards. The following are the key calibration methods and practical skills:

1、 Calibration method: step-by-step implementation, precise traceability

Reference source calibration method

Using a high-precision DC standard source (such as Fluke732C, with an annual stability of ≤ 50ppm) as a reference, compare the voltage/current output of the power supply to be calibrated with the standard source. Generate calibration curves through multi-point calibration (such as 0%, 50%, 100% range) to correct nonlinear errors. For example, when calibrating a 0-30V power supply, it is necessary to record the error values at nodes such as 5V, 15V, and 30V and input them into the analyzer.

Comparative calibration method

Use a calibrated high-precision digital multimeter (such as Keysight 34465A, 6.5bit resolution) to synchronously measure the power output, compare the displayed value of the analyzer with the measured value of the multimeter, calculate the deviation and correct it. This method is suitable for rapid on-site calibration when there is no standard source available.

Automated calibration system

Using programmable power supplies (such as Chroma62000P series) in conjunction with upper computer software to automatically complete range switching, data acquisition, and error compensation. For example, by using LabVIEW to write calibration programs, 24-hour unmanned calibration can be achieved to reduce human operational errors.

2、 Key Tip: Details determine accuracy

Temperature drift control

The power supply and analyzer need to be preheated for 1 hour in a constant temperature environment (23 ℃± 1 ℃), and calibrated after the component temperature stabilizes. Some instruments, such as the Keithley 2400 series, have built-in temperature compensation circuits that can automatically correct for temperature drift effects.

Load matching

During calibration, it is necessary to connect a load that is consistent with the actual working conditions (such as resistive, capacitive, or inductive loads) to avoid actual usage errors caused by no-load calibration. For example, when testing a battery charging power source, an electronic load that simulates the internal resistance of the battery should be used.

Optimization of cables and contact resistance

Select a low impedance (≤ 1m Ω) four terminal test wire to eliminate the impact of lead voltage drop. The contact points need to be polished with sandpaper to a metallic luster, ensuring low contact resistance (<0.1m Ω).

Regular resumption and record keeping

Establish a calibration cycle table (such as every 3 months) and record environmental temperature and humidity, calibration data, and equipment status. Potential drift can be detected in advance through trend analysis, such as three consecutive calibrations showing an increasing range error, which may require sensor replacement.

3、 Error Avoidance: Common Problems and Solutions

Noise interference: Connect a 0.1 μ F ceramic capacitor and a 10 μ F tantalum capacitor in parallel at the power output end to filter out high-frequency ripples; The input terminal of the analyzer uses shielded wires and is grounded at a single point.

Range selection: To avoid measurement values approaching the range limit (such as errors that may double when measuring 29V with a 30V power supply), prioritize selecting 50% -80% of the range.

Software compensation: For known system errors (such as 0.05% offset error of the analyzer), they can be corrected in reverse in the software through calibration coefficients.

Through systematic calibration and refined operation, the measurement uncertainty of DC power supply can be controlled within 0.01%, meeting the high-precision requirements of semiconductor manufacturing, quantum metrology and other scenarios.