B57236S0500M051 - 50 Ohm NTC Inrush Current Limiter | TDK
料号： B57236S0500M051 ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $1.45 | $1.45 |
| 10 | $1.28 | $12.80 |
| 100 | $1.05 | $105.00 |
| 500 | $0.89 | $445.00 |
| 1,000 | $0.76 | $760.00 |
B57236S0500M051 概述
An NTC inrush current limiter (also called an NTC thermistor ICL) is a temperature-dependent resistor whose resistance drops sharply as the device self-heats due to load current. At room temperature the resistance is high (here 50 ohms), limiting the initial charging current of the bulk capacitor; once equilibrium is reached during continuous operation, the thermistor settles at a low resistance (~1 ohm or less) that minimizes steady-state power dissipation. These components sit within the broader passive components taxonomy as a specialized subcategory of NTC thermistors -> thermistors -> resistors -> passive electronic components, serving as soft-start elements in AC/DC and DC/DC converter front ends.
Key electrical features include a 50 ohm nominal R25, ±20% tolerance on cold resistance, maximum steady-state current of approximately 1.9 A, and a dissipation constant that allows reliable operation in free air. The leaded through-hole construction supports conventional PC mounting and provides robust mechanical stability for the high surge currents typical of capacitor-charge events. The disc body geometry maximizes surface area for rapid thermal response, while the long lead pitch accommodates standard PCB hole spacing and allows the device to be automatically inserted.
TDK's EPCOS S 236 series uses a high-B-value NTC ceramic body formulated to deliver a high resistance ratio between cold and hot states. This wide ratio is what enables effective inrush suppression with minimal voltage drop after the converter has started. Barium-titanate-based NTC ceramics of this family exhibit fast thermal time constants, ensuring the limiter returns to its high cold resistance during the next power-up cycle.
Typical applications include switch-mode power supply (SMPS) input stages, motor soft-start circuits, transformer-coupled loads, inverter front ends, and any power-electronic system where bulk capacitors create dangerous turn-on surge currents. When specified properly the B57236S0500M051 reduces peak inrush by a factor of 5-10x versus an unprotected input, dramatically extending the life of upstream fuses, rectifiers, and relays.
When designing with this part, derate steady-state current in enclosed thermal environments. Because the limiter's hot resistance can rise further at elevated ambient temperatures, ensure the application's worst-case Imax stays below the 1.9 A rating with appropriate margin (typically 0.7-0.8 x rated current for continuous operation).
This page synthesizes distributor stock data, datasheet specifications, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
直接替换替代料： B57236S0500M051 ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： B57236S0500M051 （相同外形与封装尺寸） ——差异在于 Mounting Type, Operating Temperature.
快速对比工具——选择替代料号进行并排对比：
B57236S0250M051
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
B57236S0100M051
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
B57236S0500M051V9
✅ 直接替换 ⚠️ 规格未核验✓ 有现货
$0.78 / 个
查看数据手册 →SL12-50003
✅ 直接替换📋 参考替代料（不在目录中）
CL-90
✅ 直接替换📋 参考替代料（不在目录中）
SL12-10009
✅ 直接替换📋 参考替代料（不在目录中）
B57236S0500M051 最大额定值与电气特性
| Component Type | NTC Inrush Current Limiter (ICL) |
| Series | EPCOS B57236S (S 236) |
| Nominal Cold Resistance (R25) | 50 ohms |
| Resistance Tolerance | ±20% |
| Maximum Steady-State Current | 1.9 A |
| Disc Diameter | 0.453 in (11.50 mm) |
| 安装类型 | Through-Hole (leaded disc) |
| 工作温度 | -55C to +170C (typical NTC thermistor operating range) |
| Termination Style | Radial leads |
B57236S0500M051 standard 引脚配置指南
B57236S0500M051（standard 封装）的引脚配置。 引脚编号、功能和连接图在制造商数据手册中定义。请参阅该手册以了解确切的封装尺寸和焊接指南。
暂无详细引脚数据： B57236S0500M051.
请参阅 数据手册 以查看完整引脚配置。
典型应用
B57236S0500M051 适用于 6 应用s: Switch-Mode Power Supply (SMPS) Inrush Limiting, Motor Soft-Start Circuit Protection, Transformer-Coupled Load Front-End Protection, Solar Inverter and DC Bus Pre-Charge, Audio Amplifier Power Supply Protection, Industrial Welding and Plasma Cutter Input Stages.
Switch-Mode Power Supply (SMPS) Inrush Limiting
The B57236S0500M051 is ideally suited for placement in series with the AC/DC rectifier output or the DC bus of switch-mode power supplies, where bulk filter capacitors (typically 100-1000 uF) draw enormous charging currents at turn-on. The 50 ohm cold resistance of this TDK/EPCOS limiter limits the peak inrush current by a factor of 5-10x compared to an unprotected input, dramatically reducing stress on fuses, bridge rectifiers, and MOSFET drain structures. In a typical 250 W SMPS design, an unprotected 400 VDC bus capacitor bank can pull a peak of 200 A+ on first energization - long enough to trip input fuses or weld relay contacts. With the B57236S0500M051 in series, the peak drops below 30 A, well within the rating of common 6 A slow-blow fuses. Once the SMPS has run for a few seconds, the limiter's hot resistance settles under 1 ohm, dissipating less than 4 W at 1.9 A continuous load. Combined with an input fuse rated at 6.3 A slow-blow and a thermistor mounted 25 mm away from any heat sources for free air convection, the B57236S0500M051 provides reliable protection across the converter's full operating range.
推荐
Motor Soft-Start Circuit Protection
Across industrial motor drives and DC motor controllers, the B57236S0500M051 serves as a passive soft-start element that absorbs the commutation-capacitor charging peak in variable-frequency drives (VFDs) and limits the inrush into DC link electrolytic capacitors. The 50 ohm cold-state impedance limits the surge to a level that does not violate the drive's input rectifier Safe Operating Area. In a 1.5 kW VFD fed from 230 VAC single-phase, the DC link capacitance is typically 470 uF at 450 V. Without a limiter, the rectifier sees a peak current exceeding 800 A for 1-2 ms - enough to damage input diodes or nuisance-trip upstream breakers. The B57236S0500M051 dissipates this initial charge through the NTC body, spreading the energy over 5-10 seconds instead of milliseconds. Beyond the typical VFD topology, this TDK/EPCOS limiter also protects servo-drive DC buses and stepper-driver supplies. After cooling, the device automatically recovers its full 50 ohm cold resistance, ready for the next power cycle - a maintenance-free behavior that distinguishes it from silicon-controlled rectifier soft-starts.
推荐
Transformer-Coupled Load Front-End Protection
Primary-side turn-on of large transformers in welding inverters, UPS systems, and high-power lighting ballasts creates flux-surge currents that, combined with secondary-rectified capacitor charging, can reach 10x the nominal primary current. The B57236S0500M051 placed in series with the primary limits this surge, protecting the upstream breaker and the transformer's primary winding. In a 5 kVA UPS input stage, a 600 VA ferroresonant transformer can pull a peak of 90 A on first energization, far beyond the steady-state rated current of 25 A. The B57236S0500M051's 50 ohm cold resistance limits the peak to under 20 A, while hot resistance remains low enough to avoid audible humming at line frequency. Mounted in free air with 25 mm clearance to adjacent components, the limiter dissipates the inrush energy without derating. This same technique applies to large 3-phase PFC front ends and telecom rectifier modules. Pair with a slow-blow input fuse to achieve a coordinated protection scheme.
推荐
Solar Inverter and DC Bus Pre-Charge
Solar inverters, battery management systems, and EV on-board chargers all use large electrolytic capacitor banks on their DC bus - often 1000-3000 uF at 400-800 VDC. Without pre-charge, contactor closing creates contact-welding arcs and inrush currents that can exceed 1000 A. The B57236S0500M051 provides a passive pre-charge path in parallel with the main contactor. During pre-charge, current flows through the limiter for 5-10 seconds, allowing the bus voltage to rise gradually toward the source voltage. The contactor then closes with both sides already at similar potentials, eliminating arcing. The B57236S0500M051's 1.9 A continuous rating suits solar strings producing up to 2 kW continuous; larger systems should select the 25 ohm or 10 ohm variant of the same family. Used together with a contactor and bleed resistor, this TDK/EPCOS device substantially extends the mechanical and electrical lifetime of the contactor - a maintenance cost savings that justifies its inclusion on every pre-charge schematic.
推荐
Audio Amplifier Power Supply Protection
High-end audio amplifiers, especially Class-D designs, employ large bulk capacitors on the main supply rail - typically 2200 uF at 50-80 V - to minimize ripple. When mains is first applied, this capacitor bank acts as a near-short circuit, drawing currents that can trip breakers or damage bridge rectifiers. The B57236S0500M051 in series with the transformer secondary limits the charging peak to a safe level. In a 200 W/channel Class-D amplifier, the rail capacitance of 4400 uF at 75 VDC would draw an unprotected peak of around 300 A. With the B57236S0500M051 in series, the peak drops below 40 A and lasts 2-3 seconds - well within the 1.9 A steady-state rating once thermal equilibrium is reached. Listeners benefit: after the limiter cools, no audible thump at next power-on. The 50 ohm cold resistance is also well-matched to tube-amp filament supplies where turn-on surges stress the rectifier/regulator chain. Pair with a 5 A slow-blow fuse for a robust, audiophile-grade turn-on sequence.
推荐
Industrial Welding and Plasma Cutter Input Stages
Welding machines and plasma cutters rely on extremely high current pulses, but their input stages still need inrush protection for the DC bus capacitors that supply the welding arc. The B57236S0500M051 placed in series with the rectifier outputs prevents nuisance tripping of workshop breakers when the welder is first switched on, while its low hot-state resistance keeps voltage drop at line current below 1 V - negligible compared to the 0.85 power factor arc load. In a 200 A MIG welder, the input section typically uses a 50-100 uF 600 VDC link capacitor. Without protection, this capacitor draws a peak of 800+ A at turn-on, often tripping a 32 A workshop breaker. The B57236S0500M051's 50 ohm cold resistance drops this peak to under 25 A, well below the breaker trip curve, while its 1.9 A continuous rating exceeds the steady-state draw after the welder has stabilized. The same approach protects plasma cutter input bridges and induction-heater capacitor banks, where the inrush current is determined by ESR alone.
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推荐产品汇总
工程参考数据： B57236S0500M051 ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | B57236S0250M051 | B57236S0100M051 | SL12-50003 | CL-90 |
|---|---|---|---|---|---|
| Brand | TDK (EPCOS) | TDK (EPCOS) - same brand | TDK (EPCOS) - same brand | Ametherm | Amphenol Advanced Sensors |
| Package | Leaded disc 11.50 mm through-hole | Leaded disc 11.50 mm (same) | Leaded disc 11.50 mm (same) | Leaded disc 12 mm (drop-in) | Leaded disc ~12 mm (drop-in) |
| Cold Resistance R25 | 50 ohm | 25 ohm | 10 ohm | 50 ohm | 50 ohm (class match) |
| Steady-State Current | 1.9 A | ~2.5 A (lower R25 allows more) | ~4 A | 1.9 A (target) | 1.9 A (target) |
| Disc Diameter | 11.50 mm | 11.50 mm (same) | 11.50 mm (same) | 12 mm | ~12 mm |
| Mounting Type | Through-Hole (radial leads) | Through-Hole (radial leads) | Through-Hole (radial leads) | Through-Hole (radial leads) | Through-Hole (radial leads) |
| Operating Temperature | -55C to +170C (NTC family) | -55C to +170C | -55C to +170C | -40C to +150C | -40C to +150C (typical NTC ICL) |
| Family / Series | EPCOS B57236S S 236 | EPCOS B57236S S 236 | EPCOS B57236S S 236 | Ametherm SL12 | Amphenol CL series |
关键差异点
- Highest cold resistance in the 11.50 mm B57236 family of inrush limiters （对比 B57236S0250M051)
- Genuine EPCOS/TDK pedigree with broad distributor availability （对比 SL12-50003)
- Standardized 11.50 mm disc / 5 mm lead pitch for drop-in compatibility （对比 CL-90)
设计说明
Estimated: in free-air mounting with 25 mm clearance, the B57236S0500M051 dissipates approximately 4-6 W during the first 5-10 seconds of inrush. The NTC body temperature can reach 150C in this transient window. Provide a thermal margin of 25 mm to adjacent heat-sensitive components (electrolytic caps, relays) and avoid bundling the leads - the device relies on natural convection and lead-based heat conduction for cooling. In enclosed applications, derate steady-state current to 1.3-1.5 A (approximately 0.7-0.8 x rated) for long-term reliability.
Select the cold resistance so that, at minimum input voltage (or worst-case rectified bus), the resulting inrush peak stays within the rating of the input fuse and the bridge rectifier's non-repetitive surge current (IFSM). For a 25 ohm variant of the same family (B57236S0250M051), the peak rises by 2x; for the 10 ohm variant (B57236S0100M051) it rises 5x. Always cross-check the inrush energy against the rectifier's I^2*t rating, and choose the highest cold resistance that still meets your steady-state drop budget.
Mount the B57236S0500M051 within 50 mm of the bulk capacitor bank but away from other heat-generating components. Keep its leads straight (do not bend within 3 mm of the body, as NTC ceramics crack under bend stress). Use a fuse on its upstream side so that a downstream short-circuit safely clears through the fuse without thermally destroying the NTC. Provide a parallel bypass (relay or SCR) for high-efficiency applications that cannot tolerate the limiter's hot-state voltage drop at continuous full load.
合规信息
RoHS and REACH compliance per standard TDK/EPCOS declarations for the B57236 series. Lead-free termination process confirmed. Halogen-free status not explicitly documented in provided snippets. Not AEC-Q100 qualified - request automotive-grade variant for vehicle applications.
