Analog Angle Article

IC implements spread-spectrum EMI suppression for USB 2.0

Campbell, Calif—When faced with EMI problems, you can use various EMI reduction techniques, including carefully sized and placed passives (ferrites, capacitors, inductors) and active, spread-spectrum timing. The passive solution seems like the simpler approach, but it requires board space, usually takes numerous configuration iterations, is very layout (and PCB-revision) dependent, can degrade signal integrity and edge rise/fall time, and is prone to inadvertent defeat as a result of component substitution on the BOM by the assembly house.

PulseCore Semiconductor has introduced what it claims is the first spread-spectrum IC approach to radiated EMI reduction expressly designed for USB 2.0 links. Their PCS3P73UOOA Peak EMI Reduction IC embodies a patent-pending technique which implements a highly granular spread-spectrum algorithm, to meet the extremely tight timing and frequency-domain limits of the USB compliance standard. Rather than manage the system clocks directly, this IC is placed between the 48 MHz clock source typically used in USB 2.0 designs, and the physical-layer interface IC.

The active-suppression technique reduces radiated EMI by 3 to 5 dB, which is enough in many cases to meet compliance requirements. PulseCore says their active EMI-suppression IC preserves transmission distance, maintains critical clock edges, and has no negative impact on signal integrity.

The 8-lead IC is appropriate for motherboards, peripherals, hubs, and other USB 2.0 products. It operates from a single 3.2/2.5 V supply, and is available in TSSOP, SOIC, and 2×2 mm TDFN COL packages.—Bill Schweber

Pricing :Under $1 each, in quantities of 3000+ pieces
Availability : Sampling now

PulseCore Semiconductor ,, 1-408-879-9077.

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