What Is CAN Bus ESD Protection?

CAN bus ESD protection is a capacitance budget first: a two-line part must clamp 30 kV and still add only 25 pF per line. What the numbers decide.

Request a Quote

CAN bus ESD protection is a capacitance problem before it is a voltage problem. A two-line bus part has to clamp a fast discharge while adding little enough load that the differential signal survives, and the numbers make the trade visible: Nexperia’s PESD2CAN protects both CAN lines from a common cathode, is rated for ESD up to 30 kV and AEC-Q101 qualified, clamps at 41 V while carrying 5 A — and costs 25 pF typical, 30 pF maximum, on each line.

Last updated: October 11, 2026

Key Takeaways

CAN is a differential bus, so both lines need protection that behaves the same way — a two-line array with matched channels is the straightforward answer.
Capacitance is the constraint that decides which part is usable, and it is quoted per line at a stated frequency and bias.
Device-level ESD immunity is stated to IEC 61000-4-2; the vehicle-level test follows the ISO 10605 family, and component qualification is a separate question answered by AEC-Q101.
Clamping voltage at the surge current, not breakdown voltage alone, is what has to stay inside the transceiver’s absolute maximum ratings.
Placement matters as much as the part: a clamp a centimetre away from the connector is a clamp with extra inductance in series with it.

The Part, and What It Specifies

A CAN protection diode is defined by four rows: how many lines it covers, what voltage it blocks, what it clamps to, and how much capacitance it adds.

Nexperia’s PESD2CAN answers all four in one SOT23 package. It protects two automotive CAN bus lines, is arranged as a common-cathode pair with a 24 V reverse standoff voltage, has a peak pulse power rating of 230 W at an 8/20 µs pulse, clamps at 41 V while carrying 5 A, holds leakage below 1 nA, is rated for ESD protection up to 30 kV and complies with IEC 61000-4-2 level 4 and IEC 61000-4-5 surge, and carries AEC-Q101 qualification. Its capacitance is 25 pF typical and 30 pF maximum per diode at 1 MHz and zero bias.

Parameter (PESD2CAN datasheet values)	Value	Why it decides the design
Lines and configuration	2 lines, common cathode	Covers CAN_H and CAN_L in one package with matched channels
Reverse standoff voltage V_RWM	24 V	Must sit above the bus’s normal differential and common-mode range
Clamping voltage	41 V at I_PP = 5 A	Has to stay below the transceiver’s absolute maximum
Peak pulse power	230 W at 8/20 µs	The surge energy the part is characterised to absorb
ESD rating	Up to 30 kV; IEC 61000-4-2 level 4	The device-level immunity claim
Capacitance C_d	25 pF typ, 30 pF max at 1 MHz, V_R = 0	Loads the bus and shifts the edge rate
Leakage I_RM	Below 1 nA	Matters on a bus that is powered continuously
Package and qualification	SOT23, AEC-Q101 qualified	Assembly and the automotive evidence trail

Which Standard Applies to Which Claim

The documents are easy to mix up, and mixing them up produces a specification nobody can test.

Three separate things are in play. Device-level ESD immunity is stated to IEC 61000-4-2, where level 4 is 8 kV contact and 15 kV air discharge. Vehicle-level ESD testing is specified by the ISO 10605 family, whose levels and discharge networks are chosen by the manufacturer for the location in the vehicle. Component reliability for a discrete semiconductor in an automotive programme is covered by AEC-Q101, alongside site-level quality and production-part approval. Transient surge is a fourth thing again, covered by IEC 61000-4-5 and, for the vehicle environment, by load-dump and other electrical-load specifications such as ISO 16750-2 — which describes environmental stress, not ESD. A protection part that carries the first three has not thereby demonstrated the fourth.

Designing the Protection Around the Bus

Four decisions cover most of the risk, and each has a number attached.

Choose the standoff voltage above the bus’s operating range, so the device stays off in normal operation; 24 V is the conventional choice for a 12 V automotive system, and higher-voltage systems need the corresponding part. Check the clamping voltage at the surge current against the transceiver’s absolute maximum, because that is the number the transceiver actually experiences. Add up the capacitance the protection contributes and compare it with the edge rate the bus can tolerate at its data rate, remembering that the figure is per line and therefore appears on both halves of the differential pair. Then place the device at the connector, with a short return path to ground, because series inductance between the transient’s entry point and the clamp reduces the clamp’s effectiveness — and keep the two channels symmetric so the pair is not skewed.

The last point is worth a worked estimate. On a differential pair, a capacitance difference between the two lines converts part of the differential signal into common-mode noise; matching the channels inside one package is how a two-line array avoids that by construction. Where the same protection is built from two discrete diodes, the matching depends on two independent tolerance bands rather than one.

FAQ

What is CAN bus ESD protection?

It is protection placed at the bus connector so that an electrostatic discharge is clamped before it reaches the transceiver. On a differential bus it is normally a two-line device, such as a common-cathode pair, so that both CAN_H and CAN_L are protected symmetrically.

How much capacitance can a CAN bus tolerate?

It depends on the data rate and the total loading on the bus, but the protection’s own contribution is quoted per line at a stated frequency and bias — 25 pF typical in the part above. Higher data rates leave less room for it.

Which standards apply?

IEC 61000-4-2 for device-level ESD immunity, the ISO 10605 family for vehicle-level ESD testing, AEC-Q101 for the component qualification of a discrete semiconductor, and IEC 61000-4-5 or the vehicle’s electrical-load specifications for surge rather than ESD.

Should the protection be bidirectional?

On a differential bus, yes in effect: the pair carries both polarities, so the protection has to clamp symmetrically rather than relying on a forward-biased junction in one direction. A device with two opposing junctions, or two devices in the appropriate arrangement, provides that.

What should be checked before approving the part?

The standoff voltage against the bus range, the clamping voltage at the surge current against the transceiver’s absolute maximum, the capacitance per line, the leakage at the hot end of the temperature range, and the AEC-Q101 qualification report for the exact part.

Official Resources

References

Nexperia, PESD2CAN — CAN bus ESD protection diode — source of the two-line common-cathode configuration, 24 V reverse standoff voltage, 230 W peak pulse power at 8/20 µs, 41 V clamping at 5 A, leakage below 1 nA, ESD protection up to 30 kV, IEC 61000-4-2 level 4 and IEC 61000-4-5 compliance, 25 pF typical and 30 pF maximum capacitance, the SOT23 package and AEC-Q101 qualification. assets.nexperia.com — PESD2CAN datasheet (PDF)
Nexperia, PESD5V0S1BA — Bidirectional ESD protection diode — comparison point for a single-line bidirectional device and its 130 W, 14 V clamp and 5 nA leakage figures. assets.nexperia.com — PESD5V0S1BA datasheet (PDF)
Texas Instruments, Protection against Unsuppressed Load Dump in Automotive Systems, SNOAAA1 — source of the distinction between ESD testing and the ISO 16750-2 electrical-load family used for the standard mapping. ti.com — unsuppressed load dump application brief (PDF)
AEC-Q101 — stress test qualification for discrete semiconductors; ISO 10605 — road vehicles, electrostatic discharge test methods (standard designations).

Continue through this engineering topic

For the complete selection, design, verification, and troubleshooting path, explore the TVS ESD and Surge Protection Hub.