Littelfuse has announced its SP3384NUTG series of low capacitance TVS diode arrays for protection of 10 Gigabit Ethernet (GbE) lines. These new devices are meant to guard sensitive high-speed network communications lines from up to to 15 amps and from a maximum of ±30kV of electrostatic discharge (ESD), as defined by IEC 61000-4-5 2nd edition and IEC 61000-4-2, respectively.
The SP3384NUTG TVS diode array. Image from Littelfuse
Left unprotected, network communications are vulnerable to hazards not limited to lightning-induced surges, ESD, electrical fast transients (EFT) and cable discharge events. Through a combination of low clamping voltage and low capacitance, the new device is designed to protect 2.5, 5, and even 10 GbE differential data lines while suffering no signal degradation.
- Capacitance for each 1/0 line is only 0.5 pF
- Typical Clamping voltage (tp=8/20μs) is
- 4 volts @Ipp = 1 amp
- 12 volts @Ipp = 15 amp
- Protection is provided for four channels, or two differential data pairs
- The units actually exceed IEC (International Electrotechnical Commission) ESD protection standards
- Leaking current at 3.3 volts is 3 nA typical and 40 nA maximum
Functional block diagram of the SP3384NUTG. Image from Littelfuse
Littelfuse asserts that the new diode arrays are suitable for several applications:
- Industrial applications such as low-voltage differential signaling, (LVDS)
- Datacenter and telecom including
- 2.5G/5G/10G Ethernet
- 5G wireless backhaul
- WAN/LAN equipment
- LVDS interfaces
- Integrated magnetics
- Consumer electronics such as desktops and notebooks
This list of applications fits neatly into the mosaic of industries Littelfuse has focused on in recent years, specifically datacenters, industrial, and consumer products (especially wearables and mobile devices).
Littelfuse has a long history in SPA (silicon protection array) TVS diode arrays. According to Tim Micun, Director of Business Development, TVS Diode Arrays (SPA Diodes), “Building upon similar footprints in 1GbE and 5GbE applications, the SP3384NUTG expands our portfolio to fill a market need for ultra-strong ESD and surge protection for today’s fastest 10GbE consumer ethernet solutions.” He goes on to mention that “It is also packaged in a compact configuration that is familiar to the datacenter, telecom, and consumer electronics industries.”
Members of the SP3384NUT Series of TVS diode arrays are available in a tiny, 3.0 mm x 2.0 mm µDFN package. They have an operating temperature range of -40 °C to +125 °C. The devices are AEC-Q101 qualified, are both halogen and lead-free and are also RoHS-compliant.
Around the Industry
Engineers have learned that protecting data communication from transient electrical events is even more critical at multi-gigahertz frequencies than it is at slower speeds, and are paying more and more attention to this critical factor in their designs. As such, it is no surprise that Littelfuse isn't alone in addressing this very important aspect of the design process.
- The CDDFN10-0506N from Bourns is a transient voltage suppressor array that can protect up to six data lines. It, too is a low capacitance device, 0.3 pF typical.
- The DALC208 from STMicroelectronics (ST) can protect four lines. Peak reverse voltage is 9 volts per diode, and capacitance is 5 pF or less.
- The SRV05-4A from SMC Diode Solutions has a typical capacitance of 1.5 pF, and will cause little attenuation at data rates of up to 3.5 GHz.
When do you consider circuit protection in the design process? Share your experiences in the comments below.