Circuit Protection
Products (6)
B57236S0500M051V9 - 50Ω NTC Inrush Current Limiter | TDK
The TDK B57236S0500M051V9 is a 50 Ω ±20% NTC thermistor designed as an inrush current limiter (ICL), rated for a maximum steady-state current of 1.9 A and a lead spacing of 0.453" (11.50 mm) in a radial leaded disc package. It belongs to TDK's B57236S series of EPCOS-originated NTC surge current limiters used to suppress the capacitive inrush that occurs when switching power supplies are turned on. The V9 suffix denotes the bulk packaging variant supplied to OEM production lines. An NTC (Negative Temperature Coefficient) inrush current limiter is a thermistor whose resistance decreases as its body temperature rises. When first energized, the limiter presents its full 25°C reference resistance to the charging bulk capacitors, attenuating the instantaneous current spike. As self-heating from steady-state load current warms the device, its resistance falls to a small residual value, minimizing continuous power dissipation. The B57236S family is widely specified across SMPS inrush protection, soft-start, and precharge circuits. Key features include a 50 Ω cold resistance (R25) with ±20% tolerance, a 1.9 A maximum permissible steady-state current, low residual resistance at operating temperature, and a disc-style radial package designed for through-hole PCB mounting or wiring harness assembly. The B57236S0500M051V9 is qualified under UL (E3388) and certified to IEC 60539-1-1 (IECQ 101-QA-12, VDE 40038223, CQC China Quality Certificate) for safety-critical inrush-limiting service. Typical applications include AC switching-mode power supply input stages, server and telecom hot-plug precharge circuits, soft-start modules for large bulk capacitors, motor drive capacitor banks, and welding or induction heater power stages where uncontrolled inrush would trip breakers or stress rectifier diodes. When selecting this part, verify that the steady-state load current stays below 1.9 A and that ambient temperature at the thermistor body remains within the published derating curve. For higher steady-state currents, consider TDK's B57237S series with higher Imax ratings.
EZAEG3A50AV - 30V 0603 ESD Suppressor, 0.04pF | Panasonic
The Panasonic EZAEG3A50AV is a surface-mount multilayer varistor (MLCV) ESD suppressor designed for high-speed data line protection, rated for a continuous operating voltage of 30V with a maximum clamping voltage of 100V in an 0603 (1608 metric) chip package. As an ESD suppressor, it provides transient voltage suppression for sensitive electronics, particularly interfaces requiring low parasitic capacitance. The EZAEG3A50AV is engineered to protect high-speed signal lines from electrostatic discharge events while maintaining signal integrity at data rates up to multi-gigabit per second. An ESD suppressor is a passive circuit-protection component that clamps transient overvoltages (such as those caused by human-body-model or contact-discharge events) to safe levels, protecting downstream ICs. ESD suppressors sit hierarchically under transient voltage suppressors (TVS), then circuit protection, and ultimately electronic components. Unlike Zener-diode-based TVS clamps which add 1-5 pF of junction capacitance, the EZAEG3A50AV uses a multilayer ceramic varistor construction to achieve sub-pF capacitance, making it suitable for RF, USB, HDMI, and other high-speed interfaces where capacitance would otherwise attenuate the signal. Key features include an ultra-low capacitance of 0.04 pF (0603 size), a 30V continuous working voltage (DC), 100V maximum clamping voltage, and bidirectional polarity for AC or DC signal lines. The 0603 footprint (1.6 mm x 0.8 mm) is one of the most widely adopted chip sizes for high-volume consumer electronics, and the device is RoHS compliant and halogen-free, meeting modern environmental requirements for portable and wearable products. The internal construction is a zinc-oxide based ceramic multilayer varistor (MLCV) with silver-nickel terminations. When a transient exceeds the breakdown voltage, the MLCV exhibits a sharp non-linear resistance drop, shunting energy away from the protected line. The capacitance-vs-voltage and leakage-current-vs-voltage curves in the manufacturer datasheet characterize the device's behavior at normal signal swings. Typical applications include USB 2.0/3.0 data line protection, HDMI/DisplayPort interface guarding, smartphone antenna lines, wearable device ESD rails, and IoT sensor signal pins. The wide 30V working voltage also allows protection of industrial 24V bus lines and automotive 12V power rails exposed to inductive transients. When designing with this part, place the EZAEG3A50AV as close as possible to the connector or ESD entry point on the PCB. Use a single ground return via directly to the chassis or system ground plane. Do not exceed the 30V DC working voltage or the peak ESD pulse rating - derate working voltage by 20% for temperature to ensure long-term reliability. This page synthesizes distributor pricing, drop-in alternatives, parameter comparisons, and PCB layout notes that complement the Panasonic datasheet for engineers selecting circuit-protection components for high-speed interfaces.
LXES03TAA1-142 - 5V Bi-Dir ESD TVS Diode, 0201 CSP | Murata
The Murata LXES03TAA1-142 is a bidirectional electrostatic discharge (ESD) protection transient voltage suppressor (TVS) diode housed in an ultra-miniature 2-bump CSP package (0.60 mm x 0.30 mm, 0.6 mm thickness) classified as an 0201 (0603 metric) footprint. It is engineered to clamp fast ESD transients on low-speed signal and data lines, offering a working voltage of 5 V and a typical breakdown voltage near 7 V with a low typical capacitance of approximately 5 pF. According to the Murata product specification, this part targets automotive powertrain and safety equipment as recommended applications and is qualified to the AEC-Q100 automotive stress-test standard. A TVS (transient voltage suppressor) diode is a solid-state semiconductor device designed to protect downstream integrated circuits from high-voltage, fast-rise-time surge events such as ESD strikes (human-body model, IEC 61000-4-2), cable-discharge events, and load-dump transients. TVS diodes occupy a position in the broader component hierarchy of protection devices (TVS diode -> ESD suppressor -> surge protector -> circuit protection -> electromechanical/component). Unlike simple Zener clamps, TVS diodes are characterized by their peak pulse current (Ipp), clamping voltage, and response time (sub-nanosecond), making them the standard defense for USB, HDMI, antenna, and sensor interfaces in modern electronics. Key features of the LXES03TAA1-142 include its bidirectional polarity (no orientation required during PCB assembly), a typical line capacitance near 5 pF that preserves signal integrity on low-speed lines, an extremely small 0201 footprint that minimizes PCB real estate, and compliance with IEC 61000-4-2 ESD ratings. The bidirectional construction allows it to be placed across a signal line without polarity concerns, simplifying layout. The 5 pF capacitance makes it suitable for general-purpose digital lines, keypads, control buttons, and sensor I/O rather than high-speed differential pairs. Architecturally, the LXES03TAA1-142 uses a silicon PN-junction avalanche structure optimized for low capacitance. During an ESD event, the device transitions from a high-impedance state to a low-impedance avalanche breakdown mode within sub-nanoseconds, shunting the surge current to ground and clamping the line voltage to a safe value for the protected IC. After the transient, it returns to its high-impedance state with negligible leakage. This passive, polarity-independent behavior requires no external bias or control signals. Typical applications include automotive CAN/LIN bus protection, keyless-entry remote receivers, USB 2.0 downstream-port ESD clamps, sensor signal-line protection, and handheld/mobile device I/O protection. The AEC-Q100 qualification makes the LXES03TAA1-142 suitable for under-hood and chassis automotive modules subject to harsh EMC environments. A critical design consideration is capacitance: at 5 pF typical the part is appropriate for sub-100 MHz signal lines but may distort signals on high-speed interfaces such as USB 3.0, HDMI, or MIPI D-PHY/CPHY. For high-speed lines, choose a sub-1 pF TVS such as the LXES15TAA1-152 family. This page synthesizes distributor pricing, parametric alternatives, and AEC-Q100 design notes that go beyond the manufacturer datasheet to help engineers select the right Murata LXES03 ESD device for their interface.
MF72-010D9 - 10Ω 2A Power NTC Inrush Current Limiter | Cantherm
The Cantherm MF72-010D9 is a 10 ohm power NTC thermistor designed as an inrush current limiter (ICL), rated for 2 A continuous steady-state current, with a 0.458 ohm residual resistance at maximum current and a 11.00 mm disk body. The part provides inrush current suppression for sensitive electronics by placing itself in series with the power source to limit the current surges typically created at turn-on. A power NTC thermistor (Negative Temperature Coefficient thermistor) is a type of inrush current limiting device whose resistance decreases sharply as its body temperature rises. When power is first applied to a capacitive load, the cold thermistor presents a high initial resistance that absorbs the charging surge; once steady-state current flows, self-heating drives the resistance down to a low residual value, minimizing continuous power dissipation. This class of component sits within the broader hierarchy of circuit protection devices, between simple resistors and active solid-state soft-start circuits. Key features of the MF72-010D9 include 10 ohm nominal resistance at 25 °C with ±20% tolerance, a 2 A steady-state maximum current rating, 0.458 ohm residual resistance at rated current, 11.00 mm (0.433 inch) disk diameter, and 7.50 mm (0.295 inch) lead spacing. The through-hole radial leaded package is supplied in bulk packaging. Operating principle is purely passive: the ceramic semiconductor material self-heats under load, reducing resistance to a small fraction of the cold resistance and therefore limiting continuous power loss. Typical applications include switch-mode power supply (SMPS) input protection, AC-DC converter soft-start, motor drive inrush limiting, audio amplifier power sequencing, and battery charging systems where high peak currents could damage rectifier bridges or fuse components. The MF72 series is a long-established industry-standard form factor used globally in low-to-medium power offline power designs. When designing with the MF72-010D9, verify that the steady-state load current never exceeds the 2 A rating once the thermistor has reached its hot equilibrium resistance. Place the device on the AC side (line or neutral) of the supply, ahead of the bulk capacitor, and ensure adequate lead-form stress relief. For higher surge energy or continuous-current applications, choose a larger diameter from the same series rather than paralleling two thermistors, which can create current-sharing instability.
SL12 1R308 - 1.3Ω 8A Inrush Current Limiter NTC | Ametherm
The Ametherm SL12 1R308 is a 1.3 ohm ±20% inrush current limiting NTC thermistor rated for 8 A maximum steady-state current up to +65 °C, housed in a 12 mm radial-leaded disc package with 0.512 inch (13.00 mm) lead spacing. It absorbs up to 40 J of recommended inrush energy and is engineered to suppress the capacitive charge surge that occurs when power is first applied to capacitive loads such as switch-mode power supplies, motor drives, and audio amplifiers. An inrush current limiter (ICL) is a negative temperature coefficient (NTC) thermistor whose cold-state resistance is intentionally high to throttle the initial charging current, then self-heats and drops to a much lower hot resistance once steady-state current flows. The ICL sits in the taxonomy of circuit protection devices alongside PTC resettable fuses, NTC surge limiters, and traditional fixed resistors, and is widely deployed as a passive, low-cost alternative to active soft-start MOSFET circuits in offline AC-DC and DC-DC converters. Key specifications of the SL12 1R308 include 1.3 Ω cold resistance at 25 °C with ±20% tolerance, an 8.00 A maximum steady-state current rating up to +65 °C, and a maximum recommended inrush energy rating of 40 J. The device is UL approved per the Mouser listing and is supplied in a radial-leaded through-hole package suitable for hand or wave soldering on conventional PCBs. The thermistor body is constructed from a metal-oxide ceramic whose resistance decreases exponentially with temperature, governed by its beta constant. The SL12 1R308 belongs to Ametherm's SL12 series, which is sized for 12 mm diameter discs and offers a family of cold-resistance values to cover a broad range of steady-state current requirements from sub-amp to tens-of-amps designs. Typical applications include AC-DC switch-mode power supply input stages, motor soft-start circuits, audio amplifier power rails, capacitor bank pre-charge circuits, and UPS battery input protection. Designers select the SL12 1R308 when 8 A steady-state current and approximately 40 J of pulse energy absorption are required in a cost-effective, passive, single-component solution. When designing with this device, confirm that the maximum inrush energy of the load capacitor bank does not exceed the SL12 1R308's 40 J rating, and account for the voltage drop across the thermistor at hot resistance when calculating worst-case load regulation. This page synthesizes distributor pricing, UL certification status, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
SL12 22101 - 220Ω NTC Inrush Current Limiter, 1A | Ametherm
The Ametherm SL12 22101 is a 220-ohm, 1-amp inrush current limiter (ICL) built around a negative temperature coefficient (NTC) thermistor disc housed in a 12 mm radial-lead package. It combines a cold resistance of 220 Ω ±20 % with a maximum recommended steady-state current of 1.00 A up to 65 °C and a maximum recommended inrush energy rating of 30 J, making it well suited to smoothing the turn-on surge of capacitive and inductive loads such as switch-mode power supplies, motor drives, and audio amplifiers. An NTC inrush current limiter is a passive discrete component whose resistance drops sharply as its body self-heats from load current. At turn-on, the cold thermistor presents a high impedance that slows the charging of downstream bulk capacitors and limits the peak rectifier or MOSFET stress; once steady-state current flows, the device warms and settles at a low hot resistance (4.20 Ω at 100 % of max current per the Ametherm datasheet), so conduction losses remain small. Compared with fixed resistors, PTC fuses or active MOSFET circuits, the NTC ICL is simpler, cheaper, and self-resetting, and it is widely used as the first-line protection element on AC-DC converter inputs. Key features of the SL12 22101 include a 220 Ω ±20 % cold resistance, 1.00 A maximum steady-state current at 65 °C, 30 J maximum recommended inrush energy, 65 J actual failure instantaneous energy, 8.14 Ω resistance at 50 % of max current, 142 °C body temperature at 100 % of max current, a 12 mW/°C dissipation constant, and a 50 s thermal time constant. The disc uses Ametherm Material Type L and carries UL approval for inrush current limiting service, simplifying safety submissions for end products. Architecturally, the device is a pressed-disc NTC thermistor with tinned copper-clad steel leads (0.5 mm ±0.1 mm diameter) suitable for through-hole mounting. The 12 mm body diameter and 5.5 mm thickness support sufficient thermal mass to absorb the 30 J inrush pulse without exceeding the 65 J failure limit, while the 50 s thermal time constant lets the device recover between repeated turn-on cycles. Typical applications include AC-DC switch-mode power supply input protection, audio amplifier power-rail soft-start, motor drive inrush limiting, transformer and solenoid inrush suppression, and general capacitive-load surge current limiting where a self-resetting, cost-effective solution is preferred over a fixed resistor or active circuit. When designing with this device, derate the steady-state current for ambient temperatures above 65 °C and ensure that expected turn-on energy (½·C·V²) plus safety margin remains below the 30 J recommended rating. Allow adequate spacing around the disc for free-air cooling and consider a bypass relay or active bypass circuit if continuous conduction losses become significant at full operating temperature. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the Ametherm datasheet, including a parametric comparison against equivalent ICLs from competing suppliers and a checklist for selecting the correct cold resistance for a given bulk-capacitance load.