1. Preliminary conducted noise test results for LV power supplies Bruno Allongue CERN-PH-ESS Fernando Arteche Imperial College – CERN 21 January 2005

2. Outline  1. Introduction  2. Set-up  Description  Set-up limitation  3. Measurements  CAEN A3009  Wiener – Maraton  Wiener – PL8F12  4. Conclusions

3. 1. Introduction  DC Power distribution often used in HEP  AC-DC Conversion  DC-DC Conversion Periphery of the detector  Front End Electronics  Characteristics of DC-DC converters  High efficiency  Galvanic insulation (Input and Output)  High EMI emissions  Emissions – Conducted or Radiated  EMI emission might couple to the FEE  Cause a malfunction

4. 1. Introduction  Two kinds of EMI emissions  Radiated Emissions  Conducted Emissions - TEST  Conducted emissions – Propagation  Common Mode  Differential Mode FEE PS Conductive Noise FEE PS Conductive Noise Radiation Noise Distribution Bus Conductive Noise Conductive Noise

5. 2. EMC test Set-up  The test is focused on the output of the PS units (DC-output)  CM & (CM+DM) output emissions  The test result is compared with standard input levels - Only as a reference  A resistance is used as a load  Electronic loads are noisy  Output power is limited  Cable shields are used as return path for CM currents  They are connected to ground on one side & the other side through a capacitor  Equipment  Spectrum Analyzer (Rohde&Schwarz) – Peak mode  Current probe – ETS 91550-1

6. Cload= 1μCload= 1μF Cs = 0.1μF Cs = 0.5μ Cs = 0.1μF Icm-in Iin Icm-out Iout PS-DUT PS Cs = 0.1μF Cs = 0.5μF Cs = 0.1μF Icm-in Iin Icm-out Iout PS-DUT PS 2. EMC test - Set-up

7. 3. EMC test - CAEN A3009  Iout = 8 A – Vout = 5 V (90 % channel)

8. 3. EMC test – Wiener Maraton  Iout = 8 A – Vout = 5 V (8 % channel)

9. 3. EMC test – Wiener PL8F12  Iout = 8 A – Vout = 12 V (35 % channel)

10. 4. Conclusions  This test is preliminary  The aim was to compare the conducted emissions of 3 different switching power supplies operating with the same output load  This test is not complete and contains limitations  Wiener PS are not fully loaded  Nevertheless common mode noise is present in all PS units at the output  Additional tests should be performed