Yeonho SMH250 Wire-to-Wire Connector (25045HP-NNA): Complete Guide to Specs, Part Numbers, Retainer Lock & WTW vs WTB Selection
What Is the Yeonho SMH250 Wire-to-Wire Connector?
The Yeonho SMH250 wire-to-wire connector is a 2.5mm pitch crimp connector system manufactured by Yeonho Electronics (South Korea) for direct wire-to-wire (WTW) interconnection — connecting two cable assemblies to each other without a PCB in the signal path. The official Yeonho product designation for the wire-to-wire plug housing is 25045HP-NNA, where "NN" represents the pin count (02 through 16, even numbers only) and "A" denotes the series suffix.
This is a critical distinction that causes significant sourcing confusion: the SMH250 designation covers two separate connector families with the same 2.5mm pitch but fundamentally different mating interfaces:
- SMH250 Wire-to-Wire (this article): Plug housing 25045HP-NNA + socket housing SMH250-NNL + pin header SMH250J-NNRT. Designed for cable-to-cable connections. The plug features a red retainer locking mechanism that provides positive secondary locking beyond the terminal lance.
- SMH250 Wire-to-Board (XHS2.5): SMH250-NN socket housing + SMW250-NN PCB wafer. Designed for cable-to-PCB connections. Uses a belt-lock latch on the housing. Covered separately in our XHS2.5 / SMH250 Wire-to-Board complete guide.
If you are looking for a connector to plug a cable into a PCB header, you want the WTB version. If you are connecting two cable assemblies together — for example, a battery pigtail to a power distribution harness, or a sensor cable to a control module — the 25045HP-NNA wire-to-wire system is the correct choice.
The Yeonho SMH250 wire-to-wire connector family: plug housings (25045HP-NNA, left column), socket housings (SMH250-NNL, right column), and tin-plated copper alloy crimp terminals on carrier strip (25045TP and YST025L3, bottom). All housings are white PA nylon (UL94 V-0). Pin counts shown: 2, 4, 6, 8, 10, and 12 positions.
25045HP-NNA Series: Electrical Specifications
The following specifications are taken directly from the Yeonho Electronics 25045HP-NNA Series datasheet:
| Parameter | Specification |
|---|---|
| Pitch | 2.50mm |
| Operating Voltage | AC/DC 250V |
| Current Rating | AC/DC 3A per contact |
| Operating Temperature | −25°C to +85°C |
| Insulation Resistance | 1000MΩ minimum |
| Withstanding Voltage | No flashover and no physical damage |
| Contact Resistance (initial) | 30mΩ MAX |
| Durability (contact resistance) | 50mΩ MAX after mating cycles |
| Vibration — Contact Resistance | 50mΩ MAX |
| Vibration — Discontinuity | 1µsec MAX |
Note on the vibration specification: The 1µsec MAX discontinuity rating means that under the specified vibration profile, any signal interruption must be shorter than 1 microsecond — below the detection limit of most digital logic circuits operating below 1MHz. This makes the 25045HP-NNA suitable for vibration environments such as RC vehicles, power tools, and light industrial equipment where brief signal interruptions would cause system faults.
The Red Retainer: How the 25045HP-NNA Dual-Lock System Works
The most distinctive feature of the 25045HP-NNA plug housing is its red PA-series retainer — a secondary locking component that is absent in the wire-to-board SMH250 family and in most competing 2.5mm WTW connectors at this price point.
3D rendering of the Yeonho SMH250 wire-to-wire system: plug housing SMP250-NN (left), socket housing SMH250-NN (center), and mated view (right). The red cylindrical elements visible in the socket housing are the retainer lock pins — when the plug is fully mated, these pins engage the retainer slots in the plug housing, providing the secondary lock that prevents accidental disconnection under vibration or pull force.
The locking system operates in two stages:
Stage 1 — Terminal Lance (Primary Lock): When a crimped terminal is inserted into the plug housing from the rear, the terminal lance deflects inward during insertion and snaps back into a housing retention slot when the terminal reaches its fully seated position. This provides the initial retention force during normal handling.
Stage 2 — Red Retainer (Secondary Lock): After all terminals are inserted and the primary lance is engaged, the red retainer is pushed into its locked position on the plug housing. The retainer physically blocks the terminal lance from deflecting, preventing terminal back-out even under sustained pull force or vibration. A missing or partially engaged retainer is immediately visible during assembly inspection — the red color serves as a deliberate visual indicator.
Material and Plating Specifications
| Part | Material | Plating / Color |
|---|---|---|
| Plug Housing (25045HP-NNA) | PA series (Polyamide / Nylon) | White |
| Socket Housing (SMH250-NNL) | PA series (Polyamide / Nylon) | White |
| Retainer | PA series (Polyamide / Nylon) | Red (visual lock indicator) |
| Plug Terminal (25045TP) | Copper Alloy | Sn (Tin) Plating |
| Socket Terminal (YST025L3) | Copper Alloy | Sn (Tin) Plating |
Part Number System: How to Read 25045HP-NNA
The Yeonho ordering code for the wire-to-wire plug housing follows this structure:
25045HP – NN – A
- 25045HP: Product name — identifies the 2.5mm pitch wire-to-wire plug housing series
- NN: Pin count — two-digit number (02, 04, 06, 08, 10, 12, 14, 16)
- A: Series suffix
Examples: 25045HP-02A = 2-pin | 25045HP-08A = 8-pin | 25045HP-16A = 16-pin
Plug Housing Dimensions: 25045HP-NNA
| Part No. | Pin | A (mm) | B (mm) | D (mm) |
|---|---|---|---|---|
| 25045HP-02A | 2 | 2.5 | 5.8 | 9.2 |
| 25045HP-04A | 4 | 7.5 | 10.8 | 14.2 |
| 25045HP-06A | 6 | 12.5 | 15.8 | 19.2 |
| 25045HP-08A | 8 | 17.5 | 20.8 | 24.2 |
| 25045HP-10A | 10 | 22.5 | 25.8 | 29.2 |
| 25045HP-12A | 12 | 27.5 | 30.8 | 34.2 |
| 25045HP-14A | 14 | 32.5 | 35.8 | 39.2 |
| 25045HP-16A | 16 | 37.5 | 40.8 | 44.2 |
Height: 8.0mm | Overall depth: 24.3mm | Mating depth: 6.55mm | Body height: 20.9mm
Socket Housing Dimensions: SMH250-NNL
| Part No. | Pin | A (mm) | B (mm) | D (mm) |
|---|---|---|---|---|
| SMH250-02L | 2 | 2.5 | 5.6 | 8.0 |
| SMH250-04L | 4 | 7.5 | 10.6 | 13.0 |
| SMH250-06L | 6 | 12.5 | 15.6 | 18.0 |
| SMH250-08L | 8 | 17.5 | 20.6 | 23.0 |
| SMH250-10L | 10 | 22.5 | 25.6 | 28.0 |
| SMH250-12L | 12 | 27.5 | 30.6 | 33.0 |
| SMH250-14L | 14 | 32.5 | 35.6 | 38.0 |
| SMH250-16L | 16 | 37.5 | 40.6 | 43.0 |
Height: 9.5mm | Width (side): 8.1mm
PCB Pin Header Dimensions: SMH250J-NNRT
| Part No. | Pin | A (mm) | D (mm) |
|---|---|---|---|
| SMH250J-02RT | 2 | 2.5 | 7.8 |
| SMH250J-04RT | 4 | 7.5 | 12.8 |
| SMH250J-06RT | 6 | 12.5 | 17.8 |
| SMH250J-08RT | 8 | 17.5 | 22.8 |
| SMH250J-10RT | 10 | 22.5 | 27.8 |
| SMH250J-12RT | 12 | 27.5 | 32.8 |
| SMH250J-14RT | 14 | 32.5 | 37.8 |
| SMH250J-16RT | 16 | 37.5 | 42.8 |
Pin: 0.85mm × 0.85mm square | Pin length above housing: 7.0mm | Pin tail below PCB: 2.5mm | Housing base height: 1.7mm
Terminal Selection: 25045TP vs YST025L3
The 25045HP-NNA system uses two different crimp terminals depending on which housing side is being terminated. These terminals are not interchangeable — using the wrong terminal in the wrong housing will result in incorrect contact geometry and unreliable mating.
Left: 25045TP plug terminals (top, wider conductor barrel 2.6mm) and YST025L3 socket terminals (bottom, narrower conductor barrel 2.2mm) on carrier strips. Right: 25045HP-NNA 4-pin plug housing (top) and SMH250-NNL 4-pin socket housing (bottom). The two terminal types have different barrel geometries and are not interchangeable between housing sides.
| Terminal | For Housing | Wire Size | Plating | Conductor Barrel (W×H) | Insulation Barrel (W×H) |
|---|---|---|---|---|---|
| 25045TP | 25045HP-NNA (Plug) | AWG #22 – #26 | Sn Plating | 2.6mm × 2.6mm | 1.5mm × 1.5mm |
| YST025L3 | SMH250-NNL (Socket) | AWG #22 – #24 | Sn Plating | 2.2mm × 2.3mm | 1.8mm × 1.7mm |
Wire gauge guidance:
- AWG 22: ~0.644mm conductor diameter. Max current ~3A. Use for power lines — matches the connector's rated current.
- AWG 24: ~0.511mm conductor diameter. Max current ~2.1A. Use for signal lines and moderate-current power.
- AWG 26: ~0.405mm conductor diameter. Max current ~1.3A. Compatible with 25045TP plug terminal only — not the YST025L3 socket terminal.
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Wire-to-Wire vs Wire-to-Board: The SMH250 Selection Decision
The most common sourcing error with the SMH250 family is ordering the wrong connector type for the application. The following framework resolves this in three questions:
Question 1: Does your connection involve a PCB?
- Yes, one end connects to a PCB: → Use the WTB system (SMH250-NN socket + SMW250-NN PCB wafer). See our XHS2.5 Wire-to-Board guide.
- No, both ends are cables: → Proceed to Question 2.
Question 2: Do you need secondary locking (retainer)?
- Yes — vibration environment, field-replaceable harness, or safety-critical: → Use the 25045HP-NNA WTW system (this article). The red retainer provides dual-stage locking.
- No — benchtop, low-vibration, or frequently disconnected: → The 25045HP-NNA still works, but consider whether JST SM or HY2.0 WTW meets your needs at lower cost.
Question 3: What current and pitch do you need?
- 2.5mm pitch, up to 3A: → 25045HP-NNA (this article)
- 2.0mm pitch, up to 3A: → JST PA 2.0mm
- 2.5mm pitch, WTB belt-lock: → XHS2.5 / SMH250 WTB
- 2.5mm pitch, higher current (>3A): → JST VH 3.96mm
25045HP-NNA vs Competing 2.5mm Wire-to-Wire Connectors
| Connector | Pitch | Current | Secondary Lock | Wire Range | Pin Count | Best For |
|---|---|---|---|---|---|---|
| Yeonho 25045HP-NNA (Keszoox) | 2.5mm | 3A | Yes (red retainer) | AWG 22–26 | 2–16 | Vibration-resistant WTW, field harness |
| JST SM (2.5mm WTW) | 2.5mm | 3A | No (friction latch only) | AWG 22–28 | 2–15 | General WTW, LED strips, RC |
| Yeonho SMH250 WTB (XHS2.5) | 2.5mm | 3A | Belt-lock (WTB only) | AWG 22–24 | 2–16 | PCB-mounted connector, industrial WTB |
| Molex Mini-SPOX (2.5mm WTW) | 2.5mm | 3A | No | AWG 22–26 | 2–24 | General WTW, automotive accessories |
| JST PA (2.0mm WTW) | 2.0mm | 3A | No | AWG 22–28 | 2–14 | Compact WTW, RC battery pigtails |
| JST VH (3.96mm WTW) | 3.96mm | 10A | Yes (latch) | AWG 18–22 | 2–12 | High-current WTW, power distribution |
Key differentiator: Among 2.5mm pitch wire-to-wire connectors, the 25045HP-NNA is the only system in this comparison that includes a secondary retainer lock as a standard component. The JST SM and Molex Mini-SPOX rely on housing latch geometry alone. For applications where terminal back-out under vibration or pull force is a failure mode, the 25045HP-NNA retainer provides a measurable reliability advantage.
Common Applications
Yeonho SMH250 wire-to-wire connector mated pairs in 2-pin configuration with 22AWG red/black UL1007 cable assemblies. The upper pair shows the plug (25045HP-02A) and socket (SMH250-02L) in the unmated state; the lower pair shows the fully mated connection. The housing latch engagement is visible on the mated pair.
RC vehicles and drones: Battery-to-ESC power distribution harnesses, receiver-to-flight controller signal wiring, and motor phase extension cables where the 2.5mm pitch provides adequate current capacity (3A) and the retainer prevents disconnection under vibration.
Power tools and electric motors: Internal wiring harnesses connecting motor windings to control boards, switch assemblies to power inputs, and sensor cables to motor controllers. The 3A / 250V rating covers most low-voltage power tool signal and auxiliary power circuits.
Industrial automation: Sensor-to-controller cable assemblies, actuator wiring, and field-replaceable harnesses in light industrial equipment where the retainer lock prevents accidental disconnection during machine operation.
3D printers and CNC machines: Heated bed thermistor cables, stepper motor extension harnesses, and endstop sensor wiring. The 2.5mm pitch is a common standard in 3D printer wiring, and the retainer lock prevents disconnection from vibration during printing.
Automotive accessories: Auxiliary lighting harnesses, sensor extension cables, and accessory power distribution in 12V systems where the 250V rating provides substantial derating margin.
Consumer electronics: Internal harness assembly in appliances, battery pack wiring, and panel-to-board connections where the retainer provides long-term retention assurance.
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Crimping the 25045HP-NNA Terminal: Step-by-Step
The 25045HP-NNA system requires two different terminals (25045TP for the plug, YST025L3 for the socket). The crimping procedure is the same for both, but the die setting differs due to different barrel dimensions.
Step 1 — Strip the wire: Strip 2.5–3.0mm of insulation. The 25045TP conductor barrel is 2.6mm wide; the YST025L3 conductor barrel is 2.2mm wide. Over-stripping risks short circuits inside the housing.
Step 2 — Select the correct die: Use a ratchet crimp tool with a die set rated for 2.5mm pitch terminals. For AWG 22 with the 25045TP, target crimp height 1.4–1.6mm. For AWG 22 with the YST025L3, target 1.2–1.4mm.
Step 3 — Crimp and verify: Perform a pull test. A properly crimped AWG 22 terminal should withstand ≥20N axial pull force. Inspect the crimp profile: conductor barrel fully closed, no wire strands protruding from the sides.
Step 4 — Insert terminals into housing: Push each crimped terminal into the housing from the rear until the terminal lance clicks into the retention slot. All terminals must be fully seated before the retainer is installed.
Step 5 — Install the red retainer: Push the red retainer into its locked position on the 25045HP-NNA plug housing. It should click into place and sit flush with the housing body. A retainer that does not fully seat indicates a terminal is not fully inserted — do not force the retainer; re-seat the terminal first.
Step 6 — Mate the connectors: Align the 25045HP-NNA plug with the SMH250-NNL socket and push together until the housing latch engages. Mating force should be smooth and even across all contacts.
Frequently Asked Questions
What is the Yeonho SMH250 wire-to-wire connector?
The Yeonho SMH250 wire-to-wire connector is a 2.5mm pitch crimp connector system for cable-to-cable connections, rated at 3A / 250V AC/DC. The plug housing part number is 25045HP-NNA (2 to 16 pin, even numbers). It features a red secondary retainer lock that prevents terminal back-out under vibration — a feature not found in competing 2.5mm WTW connectors such as the JST SM or Molex Mini-SPOX. Keszoox supplies pre-crimped 25045HP-NNA cable assemblies in 22AWG UL1007 PVC.
What is the difference between 25045HP-NNA and SMH250-NN?
The 25045HP-NNA is the plug housing (cable side with red retainer). The SMH250-NNL is the socket housing (receptacle side). Both are part of the same wire-to-wire system. The SMH250-NN (without the "L" suffix) is a different product — the wire-to-board socket housing used in the XHS2.5 belt-lock WTB system. Always verify the suffix when ordering.
Is the Yeonho SMH250 wire-to-wire connector the same as XHS2.5?
No. Both use the SMH250 designation and 2.5mm pitch, but they are different systems. XHS2.5 is the wire-to-board system (SMH250-NN socket + SMW250-NN PCB wafer with belt-lock latch). The 25045HP-NNA is the wire-to-wire system (plug + socket housing, no PCB wafer). Housings and terminals are not interchangeable between the two systems. See our XHS2.5 Wire-to-Board complete guide for the WTB system.
What does the red retainer do and is it required?
The red retainer is the secondary locking component of the 25045HP-NNA plug housing. It physically blocks the terminal lance from deflecting, preventing terminal back-out under pull force or vibration. It is strongly recommended for all applications and required for vibration environments, field-replaceable harnesses, and safety-critical connections. The retainer is included with the 25045HP-NNA housing.
Can I use AWG 26 wire with the SMH250 wire-to-wire system?
AWG 26 is compatible with the 25045TP plug terminal only (wire range AWG 22–26). The YST025L3 socket terminal is rated for AWG 22–24 only. If you need AWG 26 on both ends, verify with Yeonho whether an AWG 26-compatible socket terminal is available, or use AWG 24 on the socket side.
Is the 25045HP-NNA compatible with JST SM connectors?
No. Although both use a 2.5mm pitch, the JST SM and Yeonho 25045HP-NNA have different housing geometries, terminal designs, and mating interfaces. They are not cross-compatible. See our JST SM complete guide for the JST SM system specifications.
What crimp tool do I need for the 25045TP terminal?
Use a ratchet crimp tool with a die set rated for 2.5mm pitch terminals and AWG 22–26 wire. The 25045TP conductor barrel is 2.6mm × 2.6mm; the insulation barrel is 1.5mm × 1.5mm. A universal engineer-style crimp tool (e.g., PA-09, PA-21) with the appropriate die insert is suitable for low-volume assembly.
What is the difference between SMH250-NNL and SMH250-NN?
The "L" suffix in SMH250-NNL indicates the low-profile socket housing used in the wire-to-wire system. The SMH250-NN (without "L") is the standard-height socket housing used in the wire-to-board (XHS2.5) system. The two housings have different external dimensions and are designed for different mating partners.
Can the SMH250J-NNRT pin header be used with the 25045HP-NNA plug?
Yes. The SMH250J-NNRT is a through-hole PCB pin header that mates with the 25045HP-NNA plug housing. This configuration is used when one end of the wire-to-wire system needs to terminate on a PCB — for example, a panel connector or a board-mounted interface point for a field-replaceable cable assembly.
Is the Yeonho SMH250 wire-to-wire connector RoHS compliant?
The housing materials (PA series nylon) and tin-plated copper alloy terminals are consistent with RoHS Directive 2011/65/EU requirements. Tin plating eliminates lead from the contact surface. Verify RoHS compliance documentation with your specific supplier for formal compliance records.
How does the 1μsec vibration discontinuity specification affect connector selection?
The 1µsec MAX discontinuity rating means that under the specified vibration profile, any signal interruption is shorter than 1 microsecond. This is below the detection limit of most digital logic circuits operating below 1MHz, meaning the connector will not cause detectable signal dropouts in standard digital communication protocols (UART, I²C, SPI, CAN) under vibration. This specification, combined with the red retainer secondary lock, makes the 25045HP-NNA the correct choice for vibration-sensitive applications where competing single-lock connectors may cause intermittent faults.
Summary
The Yeonho SMH250 25045HP-NNA wire-to-wire connector is the correct choice when you need a 2.5mm pitch, 3A, 250V wire-to-wire connection with secondary retainer locking. Its red retainer distinguishes it from competing 2.5mm WTW connectors (JST SM, Molex Mini-SPOX) that rely on single-stage latch retention. The 1µsec MAX vibration discontinuity specification makes it suitable for motion-sensitive applications where competing connectors without secondary locks may fail.
The system consists of three housing components (25045HP-NNA plug, SMH250-NNL socket, SMH250J-NNRT PCB header) and two terminal types (25045TP for the plug, YST025L3 for the socket) — all available in 2 to 16-pin configurations. Pre-crimped cable assemblies from Keszoox eliminate the need for crimping equipment in low-volume applications.
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