Covers ESD protection parameters, testing standards, and topologies. Introduces SEED methodology to simulate ESD behavior and ensure compatibility. Provides practical guidance for designers.

This handbook covers key ESD protection parameters, testing standards, and protection topologies. It introduces the SEED methodology to simulate ESD behavior and ensure compatibility. Overviews of sensitive interfaces highlight the need for robust protection. Practical guidance helps designers choose suitable ESD protection solutions.

This handbook covers key parameters for selecting ESD protection devices, including robustness, clamping voltage, and low capacitance. It explains ESD testing standards like IEC 61000-4-2 and Transmission-Line Pulse (TLP) testing, which provide reproducible results for qualifying components. The principles of ESD protection are discussed, including unidirectional, bidirectional, and rail-to-rail topologies. The System Efficient ESD Design (SEED) methodology is introduced to simulate ESD behavior and ensure protection devices and system chips are compatible. The handbook provides overviews of key interfaces, including USB, HDMI, MIPI, and automotive protocols, highlighting the extreme sensitivity and need for robust protection in super-speed interfaces. Practical guidance is given to help designers choose the most suitable ESD protection solutions for their applications.

Electrostatic discharge (ESD) and surge events pose increasing threats to electronic components as silicon geometries shrink and interface speeds rise. This handbook covers key parameters for selecting suitable ESD protection devices, including robustness, clamping voltage, and low capacitance. It explains ESD testing standards like IEC 61000-4-2 and Transmission-Line Pulse (TLP) testing, which provide reproducible results for qualifying components.

The principles of ESD protection are discussed, including unidirectional, bidirectional, and rail-to-rail topologies. Latch-up scenarios and the effects of parasitic inductance are also covered. The System Efficient ESD Design (SEED) methodology is introduced to simulate ESD behavior and ensure protection devices and system chips are compatible.

Common mode filters for electromagnetic interference (EMI) filtering are presented, and their combination with ESD protection is examined. Failure symptoms caused by ESD and surge events are outlined.

The handbook provides overviews of key interfaces, including USB, HDMI, MIPI, and automotive protocols like LIN, CAN, and FlexRay. It discusses the physical layer specifications relevant for ESD protection, signal integrity, and driver/receiver structure, highlighting the extreme sensitivity and need for robust protection in super-speed interfaces.

Antenna interfaces and supply line protection with TVS diodes are also covered. Throughout, practical guidance is given to help designers choose the most suitable ESD protection solutions for their applications.

ESD testing standards like IEC 61000-4-2 and IEC 61000-4-5 define waveform parameters and provide guidelines for relating voltage and current. TLP and VF-TLP testing can be used to derive key parameters like maximum surge current, peak power, clamping voltage, and dynamic resistance.

Silicon-based ESD protection solutions are preferred over spark gaps or varistors due to their low clamping voltages and lack of degradation. Topologies like bidirectional Zener diodes, rail-to-rail protection, and SCR-based designs can provide effective ESD protection.

Latch-up scenarios and the hold current/voltage of TrEOS protection devices are analyzed. Parasitic inductance and layout considerations are important for achieving effective ESD protection, which can be simulated using the SEED concept.

The chapter covers physical layer specifications and ESD protection requirements for various interfaces, including USB, HDMI, MIPI, and automotive protocols like LIN, CAN, FlexRay, and Ethernet-based BroadR-Reach. Proper ESD protection design is crucial for ensuring reliable operation of these high-speed and safety-critical interfaces.

Transient voltage suppressors (TVS) are commonly used to protect supply lines against overvoltages, clamping the voltage to the breakdown voltage when conducting current to ground. This protection is essential for portable devices against surge events.

Throughout the handbook, practical guidance is provided to help designers select the most suitable ESD protection solutions for their applications, considering factors like robustness, clamping voltage, capacitance, and compatibility with the target interface and system requirements.

Shrinking silicon geometries and high-speed interfaces have made electronic components more vulnerable to electrostatic discharge (ESD) and surge events. External ESD protection is now essential, even for internal interfaces, to ensure system-level robustness.

This handbook covers key parameters for selecting suitable ESD protection devices, including robustness, clamping voltage, and low capacitance. It explains ESD testing standards like IEC 61000-4-2 and Transmission-Line Pulse (TLP) testing, which provide reproducible results for qualifying components.

The principles of ESD protection are discussed, including unidirectional, bidirectional, and rail-to-rail topologies. Latch-up scenarios and the effects of parasitic inductance are also covered. The System Efficient ESD Design (SEED) methodology is introduced to simulate ESD behavior and ensure protection devices and system chips are compatible.

Common mode filters for electromagnetic interference (EMI) filtering are presented, and their combination with ESD protection is examined. Failure symptoms caused by ESD and surge events are outlined.

The handbook provides overviews of key interfaces, including USB, HDMI, MIPI, and automotive protocols like LIN, CAN, and FlexRay. It discusses the physical layer specifications relevant for ESD protection, signal integrity, and driver/receiver structure. Findings for the latest super-speed interfaces are shared, highlighting the extreme sensitivity and need for robust protection.

Antenna interfaces and supply line protection with TVS diodes are also covered. Throughout, practical guidance is given to help designers choose the most suitable ESD protection solutions for their applications.

ESD Protection Concepts: Testing and Simulation

The IEC 61000-4-2 standard defines the waveform parameters for ESD testing, including a fast rise time of 0.7 to 1 ns and a peak current that varies with the ESD level. The waveform has a shoulder-shaped decline over about 80 ns.

Reproducibility is a key concern in ESD testing. The first peak of the waveform can vary by ±25% due to factors like gun connection and grounding. Improper grounding can cause the first peak to disappear. Stray pulses from a missed target can also exceed the regular pulse by a factor of 2.

The IEC 61000-4-5 standard defines surge pulses with an 8/20 μs waveform, which have much higher energy than ESD pulses. This requires ESD protection devices to dissipate more heat. The standard provides guidelines for relating the open-circuit voltage to the short-circuit current.

Transmission Line Pulse (TLP) testing provides a controlled 50Ω environment to characterize ESD protection devices. It uses a rectangular pulse with 100 ns duration and 10 ns rise/fall times. Very Fast TLP (VF-TLP) uses even shorter 1-10 ns pulses with 100-600 ps transitions, allowing investigation of the first overshoot.

TLP and VF-TLP testing can be used to derive key parameters like maximum surge current, peak power, clamping voltage, and dynamic resistance. The steepness of the TLP curve, ΔV/ΔI, indicates the dynamic resistance.

When designing ESD protection, silicon-based solutions are preferred over spark gaps or varistors due to their low clamping voltages and lack of degradation. Topologies like bidirectional Zener diodes, rail-to-rail protection with pn-diodes and Zener, and rail-to-rail with SCR can provide effective ESD protection. The goal is to create a TLP curve that is to the left of the device being protected, with a high steepness to divert most of the surge current away from the sensitive circuitry.

ESD protection devices can start conducting at relatively low voltages. As the pulse voltage increases, they show a steep rise in current due to their low dynamic interface resistance. However, many ICs can only handle a limited maximum TLP current, e.g., 5 A.

The TLP curves of different ESD protection devices are compared. Avalanche-type diodes with VRWM of 5 V and 3.3 V, as well as a snap-back diode, are shown. The snap-back diode has a lower dynamic resistance, allowing more surge current to flow through it rather than the system chip (SoC), effectively protecting the SoC.

Latch-up scenarios are discussed. If a snap-back device is triggered and its on-state current exceeds the hold current of the ESD protection, latch-up can occur. However, most Nexperia ESD protection devices can withstand 100 mA for hours without damage. Latch-up may cause a soft fail, but no hardware fail, and the snap-back device can automatically return to off-state.

The hold current and hold voltage of TrEOS protection devices are analyzed. Unidirectional devices have Ihold of ~16 mA and Vhold of 1.4 V, while bidirectional devices have Ihold of ~16 mA and Vhold of 2.2 V.

The switching speed of snap-back ESD protection is discussed. TrEOS devices can turn on within 1 ns, while many other devices have much slower turn-on times, around 10 ns, which limits their ability to protect high-speed interfaces.

For ultra-high-speed interfaces, the first overshoot of an ESD strike can damage the SoC, even if the higher-energy shoulder does not. Effective ESD protection must limit this first overshoot through fast reaction time and low clamping.

Parasitic inductance and layout considerations are important for achieving effective ESD protection. The SEED (System Efficient ESD Design) concept uses an equivalent circuit simulation to predict system-level robustness, accounting for the SoC, protection device, and board parasitics.

The diode clamp model provides a very good prediction of the system's failure level, whether the failure mechanism is thermal damage or the limiting over-voltage is not reached during protection triggering. The diode clamp model has the advantage of virtually non-existent convergence problems and provides good correlation with measured fail levels.

The clamp model with snap-back extends the diode model with two additional inflection points, [Vt1, It1] and [Vh, Ih]. The clamp triggers at [Vt1, It1] and enters a low-impedance state given by Rrev for I>It1. Once I<Ih, the clamp returns to its high-impedance state. This model captures the relevant details of the actual I-V curve very well.

The Verilog-A model can be further extended with an additional inflection point to more accurately model the high-current behavior. This extended model shows a better match above 1.5 A compared to the simpler snap-back model.

To suppress unwanted overshoots at the end of a pulse, an extended Verilog-A model was created that distinguishes between increasing and decreasing current using the Verilog-A cross-function. This hysteresis model no longer contains the undesired overshoot.

The dynamic voltage overshoot during triggering of the external protection is not included in the Verilog-A model. A partially correct model may be provided by adding a small inductance in series with the protection.

The most straightforward TLP source is a current source with 50 Ω impedance, as a voltage source would not work due to the multi-valued nature of the snap-back region. The IEC 61000-4-2 gun model is based on the work by Caniggia and Liu, and can be used to simulate the discharge on an application protected by an external protection.

Examples of Verilog-A code are provided for the different model characteristics, including a simple diode clamp, a clamp with snap-back, a clamp with snap-back and an additional inflection point, and a clamp with snap-back and current hysteresis.

The USB 2.0 transmitter eye diagram has a nominal voltage swing of 400 mV to -400 mV, with a maximum voltage of -475 mV for transitions and -525 mV at other times. The receiver eye diagram has a height of 300 mV and a width reduced to 60% of the unit interval.

USB 3.0 and 3.1 use 8b10b coding to achieve a DC-free bit stream and limited disparity. The 8-bit data is split into 5-bit and 3-bit segments, which are then coded into 6-bit and 4-bit segments respectively. Running disparity is used to ensure a balanced number of 0s and 1s.

The USB 3 Gen 1 (5 Gbit/s) receiver eye has a minimum height of 100 mV and a minimum width of 0.34 unit intervals. The USB 3 Gen 2 (10 Gbit/s) receiver eye has a minimum height of 70 mV and a minimum width of 0.286 unit intervals.

The USB Type-C connector supports USB 3 Gen 2 speeds, USB 2.0 power delivery, and alternate modes like DisplayPort and Thunderbolt 3. It has 24 pins organized into two groups, with pins for differential pairs, USB 2.0 lanes, configuration channels, and power/ground. Connection orientation is detected via the configuration channels.

HDMI uses TMDS signaling with a clock channel and three data channels. HDMI 2.0 supports up to 6 Gbit/s per lane, with a minimum eye height of 150 mV and maximum data jitter of 0.6 unit intervals. The receiver eye mask has a minimum height of 300 mV and minimum width of 50% of the unit interval.

MIPI D-PHY is a synchronous interface with a master-slave configuration, using one clock lane and one or more data lanes. It supports data rates from 80 to 1500 Mbit/s per lane, with a low-power signaling mode for control commands. MIPI M-PHY and C-PHY are other MIPI physical layer standards with different signaling schemes.

MIPI D-PHY and M-PHY Signaling Concepts MIPI D-PHY uses differential signaling with two lines, TXDP and TXDN, to transmit data in high-speed mode. It supports both high-speed and low-power modes, with defined voltage levels and state transitions between them.

MIPI M-PHY is the successor to D-PHY, addressing higher data rates, better power efficiency, and more flexibility. It uses a synchronous connection between master and slave, with the clock generated via a PLL. M-PHY supports multiple high-speed GEAR modes with data rates up to 11.68 Gbps.

The M-PHY transmitter eye diagram has minimum requirements for differential AC voltage and open eye width. Similarly, the receiver eye must meet minimum voltage and width specifications to ensure signal integrity at the highest data rates.

MIPI C-PHY uses three signal lines instead of two, allowing higher data rates without needing four lines. It achieves 2.28 bits per symbol, with the combination of line voltages changing from symbol to symbol. The receiver eye diagram must have a minimum height of 80 mV and width of 0.5 unit intervals.

In-Vehicle Networking Modern vehicles contain many ECUs communicating over various network protocols, including LIN, CAN, CAN FD, and Ethernet-based BroadR-Reach. These networks have specific electrical requirements for ESD protection, signal integrity, and EMC performance.

ESD protection diodes must meet criteria like breakdown voltage, clamping voltage, and capacitance to protect transceivers while maintaining signal quality. Diode selection depends on the network type and its operating voltage range, data rate, and physical layer characteristics.

The chapter provides an overview of the key in-vehicle networking interfaces, their topologies, data rates, and standards, highlighting the importance of proper ESD protection design for reliable automotive electronics.

External clamping circuits can be applied to the CANH and CANL lines to extend the ESD robustness of the CAN network, protect the CAN transceivers, and ensure communication. The industry offers devices specifically designed to protect two CAN bus lines from damage caused by ESD and other transients.

In low-speed CAN, the Dominant state can overwrite a Recessive state. The Recessive state is the idle state and represents logical 1. In Highspeed CAN, both signal lines have a voltage level of about 2.5 V in the Recessive state, while in the Dominant state CAN_H jumps up to 3.5 V and CAN_L goes down to 1.5 V, creating a differential voltage of 2 V.

FlexRay is a fault-tolerant and high-speed bus system, operating up to 10 Mbit/s per channel using the differential signals BP and BM. It can be operated as a dual-channel system, making data available in a redundant network. ESD protection diodes with low capacitance (<20 pF) and good matching (about 2%) are required.

Automotive Ethernet 100BASE-T1 and BroadR-Reach provide 100 Mbit/s over a single unshielded twisted pair cable. The internal ESD protection of modern 100BASE-T1 PHYs triggers at 10-14V, so a protection device with lower trigger voltage should be chosen.

APIX is a dedicated automotive multimedia interface that can transmit digital video signals over a distance up to 15 m. State-of-the-art protection technology with extremely low capacitance is required to protect APIX data lines. For power over cable, a dedicated solution with high breakdown voltage and low capacitance is needed.

Transient voltage suppressors (TVS) protect supply lines against overvoltages. They start conducting current to ground when the voltage reaches the breakdown voltage, clamping the voltage to the clamping voltage. TVS protection is commonly applied at the power (charger) input of portable devices to protect against surge events.