As automotive and consumer electronics move more data at higher speeds, protecting those connections from electrostatic discharge gets harder. The protection device itself sits directly on the signal path, which means its electrical characteristics have the potential to interfere with the signal it is supposed to protect.
That creates a particular problem for interfaces such as USB4, Thunderbolt, DisplayPort, automotive Ethernet and high-speed camera links. Their data-line voltages are getting lower while data rates continue to climb. A transient voltage suppressor (TVS) diode needs to clamp an ESD event quickly enough to protect sensitive ICs, but adding too much capacitance to a high-speed line can degrade signal integrity.
Littelfuse is targeting both sides of that problem with the new AQ4315-01ETG and SP4315-01WTG bidirectional TVS diode arrays, part of its SPA Diodes portfolio.
Lower Clamping Without the Capacitance Penalty
During an ESD event, a TVS diode diverts the transient away from the protected circuitry. Clamping voltage determines how much voltage still reaches that circuitry once the protection device begins conducting.
The challenge is getting that voltage low enough without adding significant capacitance to the data line.
Littelfuse specifies typical clamping voltages between 4.5 V and 6.5 V for the new devices. The company says they can suppress ESD transients ranging from 8,000 V to 20,000 V to less than 10 V at the protected device.
At the same time, capacitance is kept to 0.25 pF for the AQ4315-01ETG and 0.17 pF for the SP4315-01WTG. That low capacitance helps reduce the effect of the protection component on high-frequency signals.
Both devices withstand ±15 kV contact and ±20 kV air discharge under IEC 61000-4-2 and have a maximum leakage current of 50 nA.
Two Devices for Automotive and Consumer Designs
Littelfuse splits the two devices primarily around their intended environments and packaging.
The AQ4315-01ETG targets automotive applications including ADAS, DisplayPort, GMSL, GVIF, LVDS and 2.5G, 5G and 10G Ethernet. It is AEC-Q101 qualified, PPAP capable and rated for operation from -40°C to 150°C.
It comes in a 1.0 × 0.6 mm SOD-882/DFN1006 package and also meets ISO 10605 requirements for automotive ESD testing.
The smaller SP4315-01WTG targets consumer and computing interfaces including Thunderbolt 5.0, USB 3.x, USB4, DisplayPort and Ethernet. It comes in a 0.63 × 0.33 mm 0201 WLCSP flip-chip package, making it suitable for designs where PCB area is limited.
Why It Matters
ESD protection is easy to overlook because under normal operating conditions it is supposed to remain largely invisible. For high-speed interfaces, though, making that protection electrically invisible becomes increasingly difficult.
Lower interface voltages leave sensitive ICs with less tolerance for an ESD transient, while faster signals leave designers with less room for the capacitance introduced by protection components.
The AQ4315-01ETG and SP4315-01WTG address those competing requirements by pairing low clamping voltage with sub-picofarad capacitance. That gives engineers a way to increase protection on increasingly sensitive data lines without introducing a component that becomes a significant part of the signal-integrity problem.
Littelfuse plans to begin sampling and production of both devices on October 20, 2026. They will be available in tape-and-reel quantities through Littelfuse and its authorized distributor network.
