SL12 1R308 - 1.3Ω 8A Inrush Current Limiter NTC | Ametherm
N.º de pieza: SL12 1R308 ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $0.8 | $0,80 |
| 10 | $0.72 | $7,20 |
| 100 | $0.62 | $62,00 |
| 500 | $0.54 | $270,00 |
| 1.000 | $0.46 | $460,00 |
SL12 1R308 Descripción general
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.
Alternativas directas para SL12 1R308 — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
SL12 1R308
✅ Sustitución directa✓ En stock
$0.46 / unidad
Ver hoja de datos →SL12 1R308-Bulk
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
SL12 1R308-T&R
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
SL12 50008
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
CL-90
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
SL12 1R308 Especificaciones
| Part Number | SL12 1R308 |
| Manufacturer | Ametherm (Vishay Ametherm) |
| Resistance @ 25 °C | 1.3 Ω ±20% |
| Maximum Steady-State Current (up to +65 °C) | 8.00 A |
| Maximum Recommended Energy Rating | 40 J |
| Series | SL12 (12 mm disc) |
| Package Type | Radial Leaded, Through-Hole |
| Lead Spacing | 0.512 inch (13.00 mm) |
| Body Diameter | 12 mm |
| Thermistor Type | NTC (Negative Temperature Coefficient) |
| Función | Inrush Current Limiter (ICL) |
| UL Approval | Yes (per Mouser listing) |
| Tipo de montaje | Through-Hole (Radial) |
| Estado RoHS | Compliant (per Ametherm datasheet) |
Configuración de pines de SL12 1R308
| Pin 1 | Lead 1 — Through-hole lead (anode equivalent for NTC); either lead is electrically equivalent as the SL12 1R308 is a two-terminal non-polarized device |
| Pin 2 | Lead 2 — Through-hole lead (cathode equivalent for NTC); either lead is electrically equivalent as the SL12 1R308 is a two-terminal non-polarized device |
Aplicaciones típicas
SL12 1R308 es adecuado para 6 aplicacións: AC-DC Switch-Mode Power Supply Input Stage, Motor Soft-Start Circuit, Audio Amplifier Power Rail Protection, Capacitor Bank Pre-Charge Circuit, UPS Battery Input Protection, Industrial Welding and Heater Control.
AC-DC Switch-Mode Power Supply Input Stage
The SL12 1R308 is widely deployed at the AC input of offline switch-mode power supplies where the bulk input capacitor bank can draw destructive surge currents at power-on. Its 1.3 Ω cold resistance limits the initial charging current to safe levels, while the 8 A steady-state rating handles continuous converter input current. The 40 J inrush energy rating is well-matched to typical 100-470 µF bulk capacitors charged from 120-240 VAC rails, where stored energy (½CV²) remains within the device's absorption envelope. Designers add a single SL12 1R308 in series with the AC line as a low-cost, fully passive soft-start solution that avoids active MOSFET circuits.
Recomendado
Motor Soft-Start Circuit
Single-phase AC induction motors and DC brush motors draw several times their running current during the first few cycles after power-on. The SL12 1R308 placed in series with the motor supply limits this starting surge, reducing mechanical stress on windings, brushes, and supply wiring. Its 1.3 Ω cold resistance adds only a small voltage drop once the motor reaches running speed and the thermistor self-heats, preserving motor torque and efficiency at steady-state. The 8 A rating covers fractional-horsepower motors up to roughly 750 W, and the 40 J energy rating accommodates the brief starting transient without damage.
Recomendado
Audio Amplifier Power Rail Protection
Class-D and high-power Class-AB audio amplifiers use large bulk capacitors on their power supply rails; when the amplifier is switched on, the inrush can trip upstream breakers or blow fuses. Inserting an SL12 1R308 between the supply and the amplifier's main reservoir caps reduces this inrush to safe levels. Its 1.3 Ω cold resistance provides substantial limiting while its low hot resistance (once warmed) keeps voltage drop and amplifier efficiency loss minimal. The 40 J energy rating comfortably absorbs the energy stored in 10,000-47,000 µF capacitor banks at typical ±50-70 V amplifier rails.
Recomendado
Capacitor Bank Pre-Charge Circuit
Industrial capacitor banks used for power factor correction, energy storage, or pulsed discharge applications require controlled pre-charge to avoid welding relay contacts and stressing capacitor dielectrics. The SL12 1R308 placed in the pre-charge path limits current during initial bank energization, then is bypassed by a contactor or MOSFET once the bank reaches operating voltage. Its 8 A steady-state rating handles continuous trickle current, while the 40 J rating handles the cumulative energy of pre-charge cycles. The radial leaded package mounts easily on the pre-charge PCB or terminal block assembly.
Recomendado
UPS Battery Input Protection
Uninterruptible power supplies connect to battery banks with hundreds of ampere-seconds of stored energy; if the battery is connected to a discharged system, the inrush current can damage connectors, cabling, and input protection devices. The SL12 1R308 in the battery input path limits this inrush to safe levels during initial connection. Its 1.3 Ω cold resistance is appropriate for typical 12-48 V battery systems, and the 40 J energy rating covers the brief transient during battery-to-inverter bus connection. Once the system is running, the thermistor's low hot resistance contributes negligible loss to overall UPS efficiency.
Recomendado
Industrial Welding and Heater Control
Resistance welding equipment and large resistive heater banks draw enormous inrush currents when switched on cold. The SL12 1R308, or multiple units in parallel, can be placed in the supply path to reduce contactor wear and prevent nuisance tripping of upstream breakers. Its 8 A steady-state rating suits smaller welders and heater banks, while the 40 J inrush rating absorbs the energy of the initial heating element temperature rise. The through-hole radial package is mechanically robust for industrial control panel mounting.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para SL12 1R308 — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | SL12 1R308 (alt SKU) | SL12 1R308-Bulk | SL12 1R308-T&R | SL12 50008 | CL-90 |
|---|---|---|---|---|---|---|
| Package | 12 mm radial leaded (0.512 in lead spacing) | 12 mm radial leaded (0.512 in lead spacing) - same | 12 mm radial leaded (0.512 in lead spacing) - same | 12 mm radial leaded (0.512 in lead spacing) - same | 12 mm radial leaded (0.512 in lead spacing) - same | 12 mm radial leaded (0.512 in lead spacing) - same |
| Brand | Ametherm (Vishay Ametherm) | Ametherm - same | Ametherm - same | Ametherm - same | Ametherm - same | Ametherm - same |
| Max Steady-State Current | 8.00 A (up to +65 °C) | 8.00 A | 8.00 A | 8.00 A | Lower (series-dependent) | 8 A-class |
| Max Recommended Energy | 40 J | 40 J | 40 J | 40 J | 40 J | 40 J-class |
| Thermistor Type | NTC | NTC | NTC | NTC | NTC | NTC |
| Lead Spacing | 0.512 in (13.00 mm) | 0.512 in | 0.512 in | 0.512 in | 0.512 in | 0.512 in |
Diferenciadores clave
- High steady-state current in compact 12 mm package (frente a SL12 50008)
- 40 J inrush energy rating in radial through-hole package (frente a Smaller-diameter ICLs (e.g., SL10 series))
- UL approved for end-product safety certification (frente a Non-UL competing ICLs)
Notas de diseño
The SL12 1R308 dissipates power as I²R during steady-state operation. At 8 A with hot resistance around 0.05 Ω, steady-state dissipation is approximately 3.2 W. According to Ametherm datasheet guidance, derate below the 8 A rating when ambient temperature exceeds +65 °C or when the device is mounted in an enclosed space with limited airflow. Estimated: 8 A through 0.05 Ω hot resistance → 3.2 W dissipation; verify against actual hot resistance from datasheet curves.
Do not exceed the 40 J maximum recommended inrush energy rating. Calculate the load capacitor's stored energy using ½CV² for the worst-case (highest expected rail voltage) and confirm it stays below 40 J with at least 25% safety margin. For larger bulk capacitors, consider the SL22 series (22 mm disc) which offers higher energy absorption in the same through-hole form factor family.
Mount the SL12 1R308 with adequate lead bending radius and strain relief; the radial leads are not designed for repeated flexing. Place the thermistor away from other heat-generating components to avoid pre-heating that would reduce its effective inrush-limiting resistance. Provide at least 10 mm clearance between the disc body and adjacent components for through-hole wave soldering and for thermal dissipation during steady-state operation.
Información de cumplimiento
RoHS compliant per Ametherm product page. UL approved per Mouser distributor listing. AEC-Q100 not applicable for passive inrush current limiter thermistor.
