BLM3401 Overview
The BL BLM3401 is a -30V P-channel enhancement-mode MOSFET fabricated on BL’s advanced trench process, providing a compelling combination of low on-resistance, low gate charge, and wide gate voltage compatibility for demanding load switch and PWM switching applications. The trench gate architecture achieves a significantly lower RDS(on) per unit die area compared to planar MOSFET processes, enabling the BLM3401 to deliver excellent conduction performance in the compact SOT-23 package — one of the smallest standard SMD housings for discrete MOSFETs. At full gate drive of VGS = -10V, on-resistance is rated at <55mΩ, while at the reduced gate voltage of VGS = -4.5V it remains competitive at <72mΩ, and even at the sub-threshold gate level of VGS = -2.5V — directly compatible with 3.3V logic outputs — it achieves <120mΩ.
The ability to operate with gate voltages as low as -2.5V is a particularly important design enabler in modern portable electronics and IoT devices, where the system supply voltage is 3.3V and GPIO drive current is limited. Many competing P-channel MOSFETs require VGS of -4.5V or more for acceptable RDS(on) — making them incompatible with direct 3.3V logic control without a level-shifting stage. The BLM3401 eliminates this constraint, allowing a microcontroller GPIO pin to directly drive the gate and fully control the power switch without additional circuitry. This logic-level compatibility, combined with a continuous drain current of -4.2A and a VDS rating of -30V, gives the BLM3401 sufficient headroom for single-cell Li-ion (max ~4.2V), 2S Li-ion (~8.4V), 12V systems, and general low-voltage load switch applications up to 30V.
BL specifies the BLM3401 as suitable for load switch and PWM applications — covering the two most common discrete P-channel MOSFET use cases in system power management. For load switching, the device’s low RDS(on) minimises voltage drop and power loss at full load current. For PWM applications such as motor speed control or DC-DC power conversion, the low gate charge characteristic enables fast switching transitions with minimal drive power from the controlling logic circuit. The BLM3401 is housed in the SOT-23 package. ABL Semi stocks it as a fully authentic, original BL factory product with flexible MOQ and compliance documentation for UK and European customers.
Key Specifications
| Parameter | Value |
|---|---|
| Device Type | P-Channel Enhancement-Mode Trench MOSFET |
| Drain-Source Voltage (VDS) | -30V |
| Continuous Drain Current (ID) | -4.2A |
| RDS(on) @ VGS = -2.5V | <120mΩ (logic-level compatible) |
| RDS(on) @ VGS = -4.5V | <72mΩ |
| RDS(on) @ VGS = -10V | <55mΩ |
| Minimum Gate Voltage for Operation | -2.5V (compatible with 3.3V logic GPIO) |
| MOSFET Technology | Advanced Trench Process |
| Gate Charge | Low (specified in datasheet) |
| Suitable Applications | Load switch, PWM power switching |
| Package | SOT-23 |
Applications
The BLM3401 is designed for P-channel load switching and PWM power control applications in low-voltage portable, consumer, and industrial electronics. Primary application areas include single-cell and multi-cell Li-ion battery load switches, USB power path management, reverse polarity protection circuits, high-side PWM motor speed control, and microcontroller-driven power rail switching. The device is equally well-suited to IoT sensor node power management, DC fan speed control stages, battery-powered handheld instrument power switches, and solar energy harvesting output switches, where its logic-level gate compatibility at -2.5V, low RDS(on), and compact SOT-23 footprint deliver efficient, space-saving P-channel switching directly from 3.3V microcontroller outputs.
Pin-to-Pin Compatible Alternatives
The BLM3401’s SOT-23 package and -30V P-channel trench MOSFET specification are shared with numerous widely deployed devices from established Western and Japanese manufacturers, enabling direct footprint substitution for BOM cost reduction and multi-source supply without any circuit or layout changes.
| Reference Part Number | Original Manufacturer | Why Choose BLM3401 |
|---|---|---|
| DMG3401L-7 | Diodes Inc. | -30V / -4.2A P-channel MOSFET in SOT-23; BLM3401 provides a direct pin-compatible replacement with equivalent trench process RDS(on) at -2.5V logic-level gate drive at a lower unit cost from ABL Semi |
| SI2301CDS-T1-GE3 | Vishay Siliconix | -30V P-channel MOSFET in SOT-23; BLM3401 offers equivalent logic-level gate drive compatibility and comparable RDS(on) performance in the same compact footprint at competitive pricing |
| AO3401 | Alpha & Omega Semiconductor | Popular -30V / -4A P-channel MOSFET in SOT-23; BLM3401 provides an equivalent or improved RDS(on) specification with trench process technology and direct footprint compatibility |
| FDN304P | onsemi (Fairchild) | -30V P-channel MOSFET in SOT-23 for load switch applications; BLM3401 delivers comparable performance with logic-level operation from 2.5V gate drive and lower on-resistance at full gate voltage |
| BSS84 | Nexperia / Vishay | Classic -50V P-channel MOSFET in SOT-23; BLM3401 provides a lower RDS(on) alternative specifically optimised for -30V load switch and PWM applications with trench-process efficiency |
Frequently Asked Questions
Is BLM3401 RoHS compliant?
Yes. The BLM3401 is fully RoHS compliant. BL manufactures the BLM3401 in accordance with EU RoHS Directive 2011/65/EU, ensuring the device is free from restricted hazardous substances including lead and mercury. ABL Semi can provide full compliance and trade documentation upon request to support UK and European regulatory and procurement requirements.
What are the pin-to-pin replacements for BLM3401?
The BLM3401 is a direct pin-to-pin replacement for widely used -30V P-channel MOSFETs in SOT-23, including the Diodes Inc. DMG3401L, Vishay SI2301CDS, Alpha & Omega AO3401, onsemi FDN304P, and Nexperia BSS84 — all sharing the same SOT-23 footprint and -30V P-channel enhancement-mode architecture. Refer to the compatibility table above for a detailed comparison.
What is the minimum order quantity (MOQ) for BLM3401?
ABL Semi offers flexible MOQ for BLM3401, supporting both prototype quantities and mass production orders. Contact us for current stock and pricing.
What package options are available for BLM3401?
The BLM3401 is available in the SOT-23 (3-pin small outline transistor) surface-mount package — the industry-standard footprint for compact discrete MOSFETs. The Gate–Source–Drain pinout of the BLM3401 SOT-23 is compatible with equivalent -30V P-channel MOSFETs from Diodes Inc., Vishay, Alpha & Omega, and onsemi, confirming its suitability as a drop-in board-level replacement. Contact ABL Semi to confirm current stock availability.
Can the BLM3401 be driven directly from a 3.3V microcontroller GPIO pin for high-side load switching?
Yes — this is one of the BLM3401’s key design advantages. In a typical high-side P-channel load switch circuit, the gate is pulled low (relative to the source) to turn the device on. For a 3.3V system where the source is connected to VCC (e.g. 3.3V), driving the gate to ground (0V) creates a VGS of -3.3V — which is above the BLM3401’s -2.5V logic-level threshold and will produce an RDS(on) of less than 120mΩ. However, note that a microcontroller GPIO cannot directly drive the gate to ground from a 3.3V supply in a high-side configuration without additional circuitry, as the GPIO output is referenced to the same ground. In practice, an NPN transistor or N-channel MOSFET is typically used to pull the P-channel gate low, with the GPIO controlling that auxiliary device. The BLM3401’s low gate charge means a small, low-current NPN such as the MMBT3904 in SOT-23 is sufficient for this function.
For complete product specifications, please refer to: