SDM11 – Post-Regulator


  • Filtering noise from DC power modules:
    • low-noise internal post-regulator
    • common-mode rejection filter
    • power supply rejection filter
  • Fixed or custom DC output voltage:
    • fixed: 3.3/5/12/15/24 V
    • custom: from 2.5 V to 32 V
  • Internal current limitation : 2 A
  • Low dropout voltage : 500 mV
  • Internal thermal limitation
  • Floating outputs
  • Isolated shutdown control input
  • 35-mm rail mounting
  • Easy wiring w/ spring-cage terminal blocks

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High-Frequency Ripple Attenuation. The transient at 600 kHz riding the output voltage of the SMPS (yellow) is completely suppressed from the SDM11's output (blue). Broaband spikes are also attenuated about 20dB.
Low-Frequency Noise Attenuation - Spectral Densities. The SMPS noise (green) is attenuated by the SDM11 (blue) over the entire range. More than 65dB at 50 kHz. Noise floor (orange).
Broadband Attenuation of SMPS Noise - Power Spectra. Switching spikes lead to a wideband noise: SMPS (yellow) and filtered SMPS using the SDM11 module (blue).


  • Cost effective solution for power supply noise sensitive systems
  • Switched mode power supply filtering
  • Linear power supply replacement
  • Ideal for rapid and reliable prototyping


The SDM11 Post-Regulator module is aimed at noise reduction of switched-mode power supplies (SMPS). Indeed, if SMPS are very attractive for their high eciency and small size, they are much noisier than their linear counterparts. While the linear power supplies’ noise mainly consists in ripple voltage at line harmonics, the DC-output voltage of SMPS presents ripple at frequencies ranging from 100 kHz to 1000 kHz and broadband noise, which is transmitted from the switcher through common-mode and dierential-mode coupling.

The SDM11 Post-Regulator module operates from the DC-output of an SMPS. It features a passive filter attenuating both common-mode and dierential-mode components of the SMPS’s output. A low-dropout voltage regulator provides an active attenuation of the SMPS’s ripple for frequencies up to 1MHz. An additional output lter extends this frequency range beyond 10MHz.

Because the SDM11 is capable of delivering output voltages from 3V to 30V under 2-A current levels, the SDM11 is the perfect choice to lter the noise of low-power SMPS. A control input is provided to allow power shutdown from an isolated remote signal. The power device is both protected against overloading or overheating operations. The current limitation can be adjusted by modifying a resistor. Likewise, the user
can set the output voltage using two programming resistors. The SDM11 is attached to the chassis both using a DIN-rail adapter or M3 screws.