B57236S0500M051V9 - 50Ω NTC Inrush Current Limiter | TDK
MPN: B57236S0500M051V9 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.62 | $16.20 |
| 100 | $1.34 | $134.00 |
| 500 | $1.12 | $560.00 |
| 1,000 | $0.96 | $960.00 |
| 5,000 | $0.78 | $3,900.00 |
B57236S0500M051V9 Overview
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.
Drop-in alternatives for B57236S0500M051V9 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with B57236S0500M051V9 (same form factor and footprint) — differing in Mounting Type, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
B57236S0500M051
✅ Drop-In✓ In Stock
$0.76 / Unit
View Datasheet →B57236S0509M051
✅ Drop-In📋 Reference alternative (not in catalog)
B57236S0250M051
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
B57236S0100M051
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
B57237S0500M051
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
B57236S0500M051V9 Specifications
| Component Type | NTC Inrush Current Limiter (ICL) |
| Manufacturer Series | B57236S |
| Resistance at 25°C (R25) | 50 Ω |
| Resistance Tolerance | ±20% |
| Maximum Steady-State Current (Imax) | 1.9 A |
| Lead Spacing | 11.50 mm (0.453") |
| Package Style | Radial Leaded Disc |
| Mounting Type | Through-Hole |
| Packaging Variant (V9) | Bulk / OEM packaging |
| Operating Temperature | -40 °C to +150 °C |
| RoHS Status | Compliant |
| REACH Status | Compliant |
| UL File | E3388 |
| IEC Certification | IEC 60539-1-1 (IECQ 101-QA-12) |
| VDE Certificate | 40038223 |
| CQC Certificate | China Quality Certificate (IEC 60539-1-1-AT0002) |
| Lead-Free (Pb) | Contains >0.1% Pb (per JEDEC JESD97, EU ELV Annex II exemption) |
| Application | Inrush current limiting, soft-start, precharge |
B57236S0500M051V9 Pin Configuration
| Pin 1 | Lead 1 — One of two through-hole axial leads (input side, no polarity) |
| Pin 2 | Lead 2 — One of two through-hole axial leads (output side, no polarity); the device is non-polar |
Typical Applications
B57236S0500M051V9 is suitable for 6 applications: Switching-Mode Power Supply Inrush Limiting, Industrial Motor Drive Soft-Start, Server and Telecom Hot-Plug Precharge, Welding and Induction Heater Power Stages, Audio Amplifier Power Supply Soft-Start, Automotive ECU Inrush Protection (ELV-Exempt Lead).
Switching-Mode Power Supply Inrush Limiting
The B57236S0500M051V9's 50 Ω cold resistance and 1.9 A steady-state rating make it well-suited for the AC input stage of a switching-mode power supply where a large bulk capacitor bank would otherwise draw a destructive inrush spike. Placed in series with the AC line ahead of the bridge rectifier, the NTC presents 50 Ω at turn-on, clamping the capacitor charging current, then self-heats during normal operation to reduce residual loss to the 1-2 Ω range. Compared to a fixed resistor of equivalent function, the NTC eliminates the continuous 5-7 W dissipation overhead, improving efficiency. Source: TDK B57236S family typical application circuit.
Recommended
Industrial Motor Drive Soft-Start
Industrial motor drives with DC-link bulk capacitors in the thousands of microfarads face severe inrush at turn-on, often tripping upstream breakers or welding relay contacts. The B57236S0500M051V9 fits in the precharge circuit to limit the inrush to safe levels; its 1.9 A Imax rating covers drives up to approximately 1 kW. The device's UL E3388 file and IEC 60539-1-1 certification allow direct use in industrial equipment covered by IEC 61800-5-1. After the first few seconds of operation, the motor drive controller can short-circuit the NTC via a parallel relay for full efficiency. Source: TDK B57236S family datasheet and IEC 60539-1-1 application note.
Recommended
Server and Telecom Hot-Plug Precharge
Hot-plug insertion in 48 V server and telecom distribution buses can draw hundreds of amps through the backplane, arcing connector pins and damaging MOSFETs. The B57236S0500M051V9 used in the precharge path of a 48 V OR-ing controller limits initial current to a safe value while the bus capacitors charge through the NTC. The 50 Ω cold value scales to the input voltage: at 48 V, the first-cycle current is bounded near 1 A, well within connector ratings. Source: TDK B57236S family datasheet and server PSU reference designs.
Recommended
Welding and Induction Heater Power Stages
Welding inverters and induction heaters concentrate massive capacitor banks on the DC link, requiring robust inrush protection at turn-on to prevent contactor arcing. The B57236S0500M051V9's 1.9 A Imax rating suits small-to-medium units up to several kVA; for larger stages, parallel multiple units or step up to the B57237S family. The V9 bulk packaging variant is preferred for OEM assembly of welding equipment, where automated insertion drives the bulk-form choice. Source: TDK B57236S family application notes.
Recommended
Audio Amplifier Power Supply Soft-Start
Large electrolytic capacitor banks on the main rail of high-power Class-D and Class-AB audio amplifiers create audible thumps and breaker trips at turn-on. The B57236S0500M051V9, placed in the AC mains path, smoothly limits inrush and eliminates the turn-on thump. Its IEC 60539-1-1 certification supports use in consumer audio equipment requiring safety certification under IEC 60065. After the initial charge period, the NTC's self-heating keeps residual dissipation negligible relative to the amplifier's continuous draw. Source: TDK B57236S family datasheet.
Recommended
Automotive ECU Inrush Protection (ELV-Exempt Lead)
12 V and 24 V automotive ECU power inputs may carry large capacitor banks for transient ride-through, drawing large inrush on ignition key events. The B57236S0500M051V9 is a drop-in protection element, and the >0.1% Pb termination content falls under EU ELV Directive 2000/53/EC Annex II exemption specifically covering NTC thermistors used in automotive electronics. The 50 Ω cold resistance and 1.9 A Imax pair well with 12 V DC-bus precharge, where the inrush target is typically held below 0.5 A. Source: TTI environmental classification and EU ELV Annex II.
Recommended
Recommended Products Summary
Engineering reference data for B57236S0500M051V9 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | B57236S0500M051 | B57236S0509M051 | B57236S0250M051 | B57236S0100M051 | B57237S0500M051 |
|---|---|---|---|---|---|---|
| Brand | TDK | TDK | TDK | TDK | TDK | TDK |
| Package | Radial Leaded Disc (11.50 mm lead spacing) | Radial Leaded Disc (11.50 mm lead spacing) - same | Radial Leaded Disc (11.50 mm lead spacing) - same | Radial Leaded Disc (11.50 mm lead spacing) - same | Radial Leaded Disc (11.50 mm lead spacing) - same | Radial Leaded Disc (similar pitch) - same family |
| Maximum Steady-State Current (Imax) | 1.9 A | 1.9 A | 1.9 A | 1.9 A | 1.9 A | ~2.5 A |
| Lead Spacing | 11.50 mm (0.453") | 11.50 mm (0.453") - same | 11.50 mm (0.453") - same | 11.50 mm (0.453") - same | 11.50 mm (0.453") - same | Similar pitch (verify datasheet) |
| Packaging Variant | V9 (bulk / OEM) | M051 (standard pack) | M051 (standard pack) | M051 (standard pack) | M051 (standard pack) | M051 (standard pack) |
| Certifications | UL E3388, IEC 60539-1-1, VDE 40038223, CQC | UL E3388, IEC 60539-1-1, VDE 40038223, CQC | Same family certifications | Same family certifications | Same family certifications | Same family certifications |
Key Differentiators
- Same-brand drop-in identical-pin alternatives available within the B57236S family (vs B57236S0500M051)
- Higher-current variant available in adjacent family (vs B57237S0500M051)
- Wide certification coverage reduces regulatory burden (vs Generic third-party NTC ICL)
Design Notes
The B57236S0500M051V9 self-heats under load. Estimated: at 1.9 A steady-state and a hot-state resistance of approximately 1 Ω, dissipation is about 3.6 W. Mount the device with sufficient lead length to act as a heat-spreader, keep it away from other heat sources (transformers, MOSFETs), and verify against the datasheet derating curve for your ambient temperature. Insufficient cooling permanently shifts the resistance.
The device is non-polar; either lead may connect to the line or neutral. Maintain 11.50 mm hole-to-hole spacing on the PCB to match the lead pitch. Keep creepage and clearance distances per IEC 60950 / IEC 62368-1 if the circuit is mains-attached. Source: TDK B57236S family layout recommendation.
Common pitfalls: do not operate continuously above 1.9 A; do not use the B57236S0500M051V9 as the only protection in a system requiring fast fault response (it is a soft-start element, not a fault-current limiter); do not substitute a different cold-resistance NTC without re-checking the inrush target, because halving R25 nearly doubles the peak inrush current. The Pb content exceeds 0.1% by weight - this is exempt under EU ELV Annex II but not under general RoHS for non-automotive new products.
Compliance Information
Body of the thermistor is RoHS compliant, but lead termination contains >0.1% Pb per JEDEC JESD97 paragraph 3.5 and falls under EU ELV Directive 2000/53/EC Annex II exemption for automotive inrush current limiters. Not AEC-Q100 qualified; not designed for AEC-Q100 automotive semiconductor use. Halogen-free status unknown - not specified in TDK datasheet.
