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lowpowerZONE Products for the week of December 10, 2007
Akros Silicon Says…
AS1601/02: Family of Active EMI Suppression Devices with ESD Protection for Ethernet Applications
Family Provides >10dB Common-Mode Suppression and ±25KV of ESD Protection to Meet Tougher EMI/EMC Metrics in Ethernet Applications
Akros Silicon, Inc. announced the availability of the AS1602 that provides an unparalleled combination of system level EMC compliance and surge protection for Ethernet applications, without impacting data transmission speeds. The device integrates unique active chokes that provide 10dB of additional common mode (CM) noise suppression over the entire Ethernet bandwidth (1MHz to 125MHz), allowing designers to meet Class B compliance (FCC Part 15 or CISPR22) effectively “Designing for EMC” from early in the design process. Additionally, the AS1602 provides an unprecedented level of ESD protection by enabling the system to exceed +/- 25kV air discharge (IEC 61000-4-2 specifications) and +/-12kV cable discharge event (CDE).
“With the AS1602 featuring active EMI & ESD suppression for Ethernet applications, Akros Silicon is addressing protection requirements for any equipment that connects to LANs,” said Jag Bolaria, senior analyst with the Linley Group. “This product is uniquely positioned in the market as an industry-first due to it being an active device, which provides customers with a system-level protection solution.”
Alternative solutions meet EMI and system ESD requirements through the use of external passive components e.g. diodes/TVS or magnetic chokes. These passive components add significant parasitics that degrade the Ethernet performance requiring multiple design turns to meet the toughest EMC requirements with little margin. In some cases the designs go through a complete re-design in order to meet the tough EMC requirements. By comparison, Akros’ AS1602 allows designers to solve both EMC and ESD suppression using a single, compact IC, enabling them to get products to market earlier by eliminating the EMC tweaking required in the past.
“EMC compliance is one of the major challenges faced by system designers,” said Ven Shan, vice president of marketing, Akros Silicon. “The AS1602 will help to reduce the arduous hours of debug efforts in the lab and limit or eliminate multiple board spins so customers can avoid product launch delays.”
EN-Genius Says…
I hate to sound like a worn-out 78, but if analog (RF) engineers had been more heavily involved in specifying data transmission systems there would be a lot fewer problems. As it is, the analog guys have to step in and fix them, or at least Band-Aid them. With Ethernet systems one of the big, and growing, hiccups is EMI. The Ethernet transformers offer some common-mode suppression but the PHY suppliers have difficulty getting to the Class B requirements of FCC Part 15 and CISPR22. These standards are an absolute consumer-used requirement. Even if a vendor achieves marginal compliance with Class B he knows that manufacturing standard tolerances might throw a lot of his yield back into Class A, without anyone knowing. Everything from board layout to parasitics can cause EMI problems and there are few vendors who have the engineering experience to tackle them.
The AS1601 adds at least another 10 dB to the suppression (when used with the Ethernet magnetics) giving a larger margin to the designs on the Class-edge and allowing a lot of other decidedly Class A systems to get into a much larger marketplace.
The additional suppression comes from what Akros is calling “Active Choke Technology”...but that is a little disingenuous. From what I have seen it is more like an active clamp, with two paths looking at and operating on both the positive and negative signals of the active pair. The amount of CM suppression can be changed a little with an external pin’s voltage state, increasing it (at a cost in quiescent) or reducing it (and saving power). A second pin allows the bandwidth to be improved a little, again at a cost.
The power rail can be +2.5 V to 3.3 V and at the former the typical power dissipation is 90 mW with the default pin settings. The differential insertion loss is quoted at less than 0.2 dB out to 100 MHz and a graph in the data sheet shows it be virtually zero out to about 70 MHz where it just breaks away a little. The minimum common-mode PHY noise rejection (working with Ethernet magnetics) is 30 dB at 1 MHz, and 10 dB at 100 MHz.
The AS1601 is a dual channel part so only one is required for the 4-wire 10/100 Ethernet, while two are required for the 8-wire 10/100/1000 Ethernet. The connections are between the PHY and the transformers. The parts are both specified over the industrial temperature range of -40°C to +85°C.
The JESD22-A114 human body model ESD of the AS1601 is ±2 kV. This increases to ±8 kV on the AS1602 which offers the same common-mode noise suppression but also adds a lot more ESD protection: both air discharge and cable discharge. The former is ±25 kV and the latter is ±12 kV.
Protection is provided for positive ESD strikes with a stack of diodes, biased so as to not distort the signals. Negative ESD strikes are handled through output nMOS bulk diodes. The parts (again one for 10/100 Ethernet and two for 10/100/1000 Ethernet) should be connected close to transformer and ferrite beads (on each line) will help drive strikes towards them.
It’s always nice to see a start-up that has been pointed in the right direction, apparently from the get-go. They have product -- and still have money in the bank -- and they made the right decision at this stage in their development to go outside the founders for a CEO who knows the sales/marketing side of our industry, knows the questions to ask, and can deliver customers by putting the right team together. Choosing products that fit a niche (as Akros has decided to with PoE-type items) will allow them to build a reputation: rather than one of those sorry companies in our business who haven’t yet decided, it seems, what they want to be when they grow up. These two products aren’t directly PoE (yet) but they fill a much wanted need in the LAN market where the company will be. If they continue to do things right. buyers will accept the pedigree of the investors, the board, and the employees and approve purchase of parts from Akros. They will do very well, I believe. Although designed, initially, for Ethernet systems there are a great number of other systems in the VoIP, WAP, STB, and networked devices world where they will also end up.
The AS1601 and AS1602 are in Pb-free QSOP-16 priced at $1.23 and $1.60, respectively, in 1-k piece lots.
Product Page AS1601
Product Page AS1602
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