Moteur de recherche de fiches techniques de composants électroniques |
|
ADM3311 Fiches technique(PDF) 11 Page - Analog Devices |
|
ADM3311 Fiches technique(HTML) 11 Page - Analog Devices |
11 / 12 page ADM3311E –11– REV. A Table V. Test Severity Levels (IEC1000-4-3) Field Strength Level V/m 11 23 310 EMISSIONS/INTERFERENCE EN55022, CISPR22 defines the permitted limits of radiated and conducted interference from Information Technology (IT) equipment. The objective of the standard is to minimize the level of emissions both conducted and radiated. For ease of measurement and analysis, conducted emissions are assumed to predominate below 30 MHz and radiated emissions are assumed to predominate above 30 MHz. CONDUCTED EMISSIONS This is a measure of noise that is conducted onto the line power supply. Switching transients from the charge pump, which are 20 V in magnitude and contain significant energy, can lead to conducted emissions. Other sources of conducted emissions can be due to overlap in switch on times in the charge pump voltage converter. In the voltage tripler shown in Figure 27, if S2 has not fully turned off before S4 turns on, this results in a transient current glitch between VCC and GND which results in conducted emissions. It is therefore important that the switches in the charge pump guarantee break-before-make switching under all condi- tions so that instantaneous short circuit conditions do not occur. The ADM3311E has been designed to minimize the switching transients and ensure break-before-make switching thereby minimizing conducted emissions. This has resulted in the level of emissions being well below the limits required by the specifi- cation. No additional filtering/decoupling other than the recom- mended 0.1 µF capacitor is required. Conducted emissions are measured by monitoring the line power supply. The equipment used consists of a LISN (Line Impedance Stabilizing Network) which essentially presents a fixed impedance at RF, and a spectrum analyzer. The spectrum analyzer scans for emissions up to 30 MHz and a plot for the ADM3311E is shown in Figure 28. + + INTERNAL OSCILLATOR GND C2 C1 S1 S2 S3 S4 VCC + C4 V+ = 3VCC VCC VCC S5 S6 S7 Figure 27. Charge Pump Voltage Tripler 1 2 SWITCHING GLITCHES Figure 28. Switching Glitches FREQUENCY – Hz 90 10 100k 10M 1M 80 70 60 50 40 30 20 EN 55022 CLASS B CONDUCTED QUASI-PEAK dB V Figure 29. Conducted Emissions Plot RADIATED EMISSIONS Radiated emissions are measured at frequencies in excess of 30 MHz. RS-232 outputs designed for operation at high baud rates while driving cables can radiate high frequency EM energy. The reasons already discussed which cause conducted emissions can also be responsible for radiated emissions. Fast RS-232 out- put transitions can radiate interference, especially when lightly loaded and driving unshielded cables. Charge pump devices are also prone to radiating noise due to the high frequency oscillator and high voltages being switched by the charge pump. The move toward smaller capacitors in order to conserve board space has resulted in higher frequency oscillators being employed in the charge pump design. This has resulted in higher levels of emis- sion, both conducted and radiated. The RS-232 outputs on the ADM3311E products feature a controlled slew rate in order to minimize the level of radiated emis- sions, yet are fast enough to support data rates up to 230 kBaud. TURNTABLE DUT RADIATED NOISE ADJUSTABLE ANTENNA TO RECEIVER Figure 30. Radiated Emissions Test Setup |
Numéro de pièce similaire - ADM3311 |
|
Description similaire - ADM3311 |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |