1.5KE18AG - 18V 1500W Unidirectional TVS | onsemi
MPN: 1.5KE18AG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.48 | $4.80 |
| 100 | $0.34 | $34.00 |
| 500 | $0.26 | $130.00 |
| 1,000 | $0.21 | $210.00 |
| 5,000 | $0.17 | $850.00 |
1.5KE18AG Overview
The "1.5KE" series defines a family of glass-passivated-junction transient voltage suppressors widely used as circuit-protection devices. A TVS diode is a solid-state silicon device that clamps an overvoltage event by avalanche breakdown, shunting transient energy away from downstream circuitry. Within the broader protection hierarchy, TVS diodes sit alongside metal-oxide varistors (MOVs) and gas discharge tubes as fast-response (< 1 ns) suppressors, prized over fuses because they self-recover after the transient has decayed.
Key features of the 1.5KE18AG include a working standoff voltage of 15.3 V, a maximum clamping voltage of 25.2 V at 59.5 A peak pulse current, and a peak pulse power rating of 1500 W for an 8/20 us waveform (per IEC 61000-4-5). The device offers unidirectional polarity, a glass-passivated die for stability, and a Surmetic axial package with operating junction temperature up to 175 C.
The 1.5KE18AG uses an avalanche-mode silicon-junction Zener die, where the junction is glass-passivated for long-term stability and moisture resistance. Its low Zener impedance and fast response time allow it to clamp transient events from ESD, inductive load kickback, and lightning-induced surges within nanoseconds.
Typical applications include protection of 12 V and 15 V dc power rails, automotive ECU inputs, industrial PLC I/O lines, telecom -48 V system protection, and USB/HDMI interface guarding on consumer equipment.
When selecting layout, mount the 1.5KE18AG as close as possible to the protected connector or IC pin and minimize lead length to reduce parasitic inductance, which otherwise degrades clamping effectiveness at high dv/dt.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single anchor for board-level protection decisions.
Drop-in alternatives for 1.5KE18AG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
1.5KE18A
✅ Drop-In📋 Reference alternative (not in catalog)
1.5KE18A
✅ Drop-In📋 Reference alternative (not in catalog)
1.5KE18A-G
✅ Drop-In📋 Reference alternative (not in catalog)
1.5KE18AG
✅ Drop-In✓ In Stock
$0.17 / Unit
View Datasheet →1.5KE18A
✅ Drop-In📋 Reference alternative (not in catalog)
1.5KE18AG Specifications
| Series | Mosorb 1.5KE |
| Type | Zener (TVS) |
| Polarity | Unidirectional |
| Working Peak Reverse Voltage (Vrwm) | 15.3 V |
| Breakdown Voltage (Vbr) | 17.1 V (min) at 1 mA |
| Clamping Voltage (Vc) | 25.2 V max at 59.5 A |
| Peak Pulse Current (Ipp) | 59.5 A (8/20 us) |
| Peak Pulse Power (Pppm) | 1500 W (8/20 us) |
| Steady-State Power Dissipation | 6.5 W |
| Response Time | < 1 ns (typical) |
| Operating Junction Temperature | -65 C to +175 C |
| Package | Axial (Surmetic), Through-Hole, 2 pins |
| Mounting Type | Through-Hole |
| Terminal Position | AXIAL |
| Terminal Form | WIRE |
| Number of Terminals | 2 |
| RoHS Status | Compliant |
| JEDEC Register | Glass-passivated junction |
1.5KE18AG Pin Configuration
| Pin 1 | Anode — Positive terminal (axial lead) |
| Pin 2 | Cathode — Negative terminal marked with band on body |
Peak Pulse Power Derating vs Pulse Duration
Typical Applications
1.5KE18AG is suitable for 7 applications: 12 V DC Power Rail Protection, Automotive ECU Input Protection, USB and HDMI Port Guard, Industrial 24 V System Surge Clamp, Telecom -48 V Line Card Protection, Inductive Load Kickback Clamp, Security and Surveillance Camera Input Protection.
12 V DC Power Rail Protection
The 1.5KE18AG's 15.3 V working voltage and 25.2 V clamping ceiling make it a natural fit for 12 V dc distribution rails in industrial control cabinets, PLCs, and building-automation nodes. A 12 V rail that may see inductive kickback from solenoids or relay coils needs a TVS that remains idle during normal 13.8 V float-charge operation but instantly avalanches above 17.1 V. The 1500 W peak rating handles IEC 61000-4-5 surges and indirect lightning strikes on field cabling, protecting downstream buck converters, MCUs, and gate drivers. Place the device within 25 mm of the input terminal with a low-inductance ground return so the 8/20 us waveform fully clamps rather than overshooting due to trace inductance.
Recommended
Automotive ECU Input Protection
The 1.5KE18AG was originally designed to absorb automotive load-dump transients per ISO 7637-2 on 12 V vehicle buses, with 1500 W peak handling the worst-case 100 V load-dump pulse. Inside an ECU the part sits at the alternator feed line, clamping before the 5 V or 3.3 V regulator, while its 15.3 V Vrwm ensures no leakage during cranking dips and 13.8 V float conditions. The axial Surmetic package survives under-hood thermal cycling (-40 C to +125 C) and through-hole leads withstand vibration. For 24 V truck electrical systems, step up to the 1.5KE30AG or 1.5KE36AG variant in the same drop-in footprint.
Recommended
USB and HDMI Port Guard
USB 2.0, HDMI, and other consumer-facing high-speed ports benefit from a TVS like the 1.5KE18AG when the upstream Vbus rail is 5 V and the port must tolerate hot-plug arcs or charged-cable events. The 15.3 V Vrwm exceeds 5 V Vbus by a wide margin, so capacitance loading of the data lines is irrelevant; the device shunts only overvoltage events. For differential data-line protection (D+/D-, TMDS pairs) prefer a bidirectional TVS array; for Vbus protection the 1.5KE18AG's 59.5 A peak current absorption handles in-rush surges that fuse-style solutions cannot reset automatically.
Recommended
Industrial 24 V System Surge Clamp
Inside 24 V industrial systems such as PLCs, motor starters, and sensor power supplies, the 1.5KE18AG provides secondary protection downstream of a primary gas-discharge tube or varistor, clamping fast transients that pass the slower primary stage. With 25.2 V clamping at 59.5 A peak, the device contains let-through energy well below the rating of downstream 24 V-tolerant components. The 6.5 W steady-state dissipation supports continuous low-energy events without thermal runaway. When designing 24 V industrial input protection, often pair the 1.5KE18AG with a higher-voltage TVS such as the 1.5KE30AG for two-stage coordinated clamping.
Recommended
Telecom -48 V Line Card Protection
The 1.5KE18AG can serve as secondary protection on telecom line cards where the -48 V feed enters through a fuse or PTC and then needs a TVS to clamp fast transients before reaching DC-DC converters. While the working voltage 15.3 V is below the steady -48 V bus voltage, the 1.5KE series includes 60 V and higher variants better suited as primary clamps; the 18 V part is useful downstream for protecting low-voltage logic and ASICs. The axial through-hole package suits the ruggedized line-card form factor and supports wave-solder reflow.
Recommended
Inductive Load Kickback Clamp
When 12 V or 15 V solenoids, relays, or small motors share a supply with sensitive logic, the 1.5KE18AG clamps the flyback spike when the coil de-energizes, protecting the switching transistor and the 12 V rail from ringing excursions that can exceed 80 V. The 1500 W peak and 59.5 A peak current handle the energy stored in even moderately-sized 12 V relay coils in a single event. Place across the relay coil (cathode to +V, anode to switching node) so the part conducts the kickback into the supply, not ground.
Recommended
Security and Surveillance Camera Input Protection
Outdoor PoE and 12 V security cameras need robust transient protection on the dc input because long cable runs pick up lightning-induced surges. The 1.5KE18AG placed at the camera-end power input clamps the arriving surge to 25.2 V before it reaches the PoE PD controller or buck regulator; the 1500 W rating handles representative Class D 1 kV surges when paired with a gas-discharge tube at the cable entry. The axial package is repairable in the field - service technicians can swap a blown TVS without replacing the entire camera PCB.
Recommended
Recommended Products Summary
Engineering reference data for 1.5KE18AG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | 1.5KE18A (onsemi) | 1.5KE18A (Littelfuse) | 1.5KE18A-G (Comchip) |
|---|---|---|---|---|
| Package | Axial (Surmetic) Through-Hole | Axial (Surmetic) - same | Axial (Surmetic) - same | Axial (Surmetic) - same |
| Brand | onsemi | onsemi | Littelfuse | Comchip Technology |
| Working Voltage (Vrwm) | 15.3 V | 15.3 V | 15.3 V | 15.3 V |
| Clamping Voltage (Vc max) | 25.2 V at 59.5 A | 25.2 V at 59.5 A | 25.2 V at 59.5 A | 25.2 V at 60 A |
| Peak Pulse Power (Pppm) | 1500 W (8/20 us) | 1500 W | 1500 W | 1500 W |
| Polarity | Unidirectional | Unidirectional | Unidirectional | Unidirectional |
| Steady-State Power | 6.5 W | 6.5 W | 5.0 W | 5.0 W |
| Junction Temperature Range | -65 C to +175 C | -65 C to +175 C | -55 C to +175 C | -55 C to +150 C |
| Mounting Type | Through-Hole | Through-Hole | Through-Hole | Through-Hole |
| RoHS Compliance | Yes | Yes | Yes | Yes |
Key Differentiators
- Original Mosorb design heritage with mature second-source ecosystem (vs 1.5KE18A (Littelfuse))
- Slightly higher steady-state dissipation rating than second sources (vs 1.5KE18A (Littelfuse / Comchip))
- Wider junction temperature rating than second sources (vs 1.5KE18A-G (Comchip))
Design Notes
Place the 1.5KE18AG within 25 mm of the protected input terminal or IC pin and use a wide, short ground-return trace to minimize parasitic inductance. Estimated: lead+trace inductance of 10 nH at di/dt of 1 kA/us adds approximately L*di/dt = 10 V overshoot on top of the datasheet 25.2 V clamping ceiling. For sub-nanosecond transient suppression, a tight, low-inductance layout is the single biggest factor in real-world clamping effectiveness, more important than selecting a slightly higher-rated TVS.
The 1.5KE18AG can absorb 1500 W peak for an 8/20 us event but only 6.5 W steady-state. Estimated: at ambient 70 C with theta_JA around 50 C/W (axial leaded), the junction-to-ambient rise is 50 * P = 325 C per watt, which derates allowable continuous power to roughly 0.5-1 W without forced air. For repetitive surge environments (e.g., motor-drive inverters) provide thermal copper mass or forced cooling so the part can recycle between events without thermal runaway.
Do not confuse the 1.5KE18AG (unidirectional, 15.3 V Vrwm) with the 1.5KE18CA (bidirectional, 15.3 V) or the 1.5KE30AG (unidirectional, 25.7 V Vrwm) - substituting either causes immediate circuit failure or no clamping. Reverse insertion defeats TVS operation and may rupture the package during the next surge event. Verify polarity by the cathode band marking per the onsemi datasheet before soldering.
Use the Surmetic axial package's lead spans - typically 9.5 mm - to set your hole pitch. Provide strain relief if the TVS is at a cable entry where mechanical flex could fatigue the leads. Where two TVS devices are placed in parallel (for higher surge handling), match them with the same MPN and source from one reel to minimize avalanche-impedance mismatch and ensure one device does not hog the surge current.
When designing for IEC 61000-4-5 (surge) or ISO 7637-2 (automotive load-dump) compliance, the 1.5KE18AG alone may need to be paired with a primary-stage gas-discharge tube or varistor for full system-level compliance. Single-stage TVS solutions typically meet Category 2 (1 kV) but struggle with Category 4 (4 kV) without primary coordination. Document the test setup and waveform on the design's compliance report.
Compliance Information
Surmetic axial package is RoHS compliant per onsemi product page. Halogen-free status not explicitly listed in retrieved data. The part is industrial-grade - AEC-Q100 qualification is not applicable since the G suffix here denotes Surmetic packaging, not automotive grade; for AEC-Q100 needs, check onsemi's 1.5KE18AG-Q variant. Conflict-minerals compliance is published per onsemi's annual CMRT filing.
