BSS138L - 50V 200mA N-Channel MOSFET SOT-23 | onsemi
MPN: BSS138L ✓ פעילBSS138L סקירה
A MOSFET (metal-oxide-semiconductor field-effect transistor) is a voltage-controlled switching device within the broader family of transistors and discrete semiconductors. Small-signal MOSFETs like the BSS138L occupy the low-power end of the power MOSFET hierarchy, sitting between general-purpose bipolar junction transistors and larger medium-power SOT-223/DPAK devices. Because the gate is isolated by an oxide layer, the device draws essentially zero DC gate current, allowing direct drive from microcontroller GPIO pins and logic-level 3.3 V or 5 V signal sources.
Key features include trench MOSFET technology that minimizes on-state resistance (approximately 3.5 ohms RDS(on) at 10 V gate drive), logic-level gate threshold enabling direct 3.3 V/5 V drive, rugged and reliable fast-switching performance, and the compact industry-standard SOT-23 footprint that keeps board area under 3 mm x 3 mm including pads.
Technically, the BSS138L is produced using onsemi high-cell-density trench MOSFET technology, which increases channel density per die area, reducing RDS(on) while preserving fast switching transition times well suited to PWM loads. The enhancement-mode structure means the device is OFF at zero gate-source voltage and turns ON with a positive gate voltage above threshold, simplifying level-shifting and load-switch circuits in mixed-voltage systems.
Typical applications cited by onsemi include DC-DC converters and power management in portable, battery-powered products such as computers, printers, PCMCIA cards, and cellular and cordless telephones. It is also widely used as a level shifter between 3.3 V and 5 V logic domains and as a low-side load switch for LEDs, relays, and sensors.
Design consideration: with a 3.5 ohm on-resistance, conduction loss at the full 200 mA rating is roughly 0.14 W (I2R estimate), a meaningful fraction of the 350 mW package limit, so derating at elevated ambient temperatures is advisable.
This page synthesizes distributor pricing, verified drop-in alternatives, pinout data, and practical design notes in one place, adding sourcing and engineering value beyond the raw manufacturer datasheet.
חלופות תחליף ישיר עבור BSS138L — אותו מארז, תואם פין-לפין. חלקים במארז שונה הדורשים עיבוד מחדש של ה-PCB אינם נכללים.
וריאנטים בסדרה זו
דגמים מאותה סדרה התואמים Drop-in עם BSS138L (אותו גורם צורה וטביעת רגל) — שונים ב Package, Continuous Drain Current (Ta), Operating Mode, Packaging, Power Dissipation (Ta).
BSS138NH6327XTSA2
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←BSS138LT1G
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←BSS138-7-F
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
BSS138-13
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
2N7002LT1G
✅ Drop-Inצור קשר לקבלת מחיר
הצג גיליון נתונים ←IRLML6344TRPBF
✅ Drop-In📋 חלופה להתייחסות (לא בקטלוג)
BSS138L דירוגים מרביים ומאפיינים חשמליים
| Polarity | N-Channel |
| Operating Mode | Enhancement Mode |
| VDS Drain-Source Voltage | 50 V |
| Continuous Drain Current (Ta) | 200 mA |
| Power Dissipation (Ta) | 350 mW |
| RDS(on) Max | 3.5 ohm |
| Technology | Trench MOSFET, high cell density |
| Gate Type | Logic Level |
| מארז | SOT-23-3 |
| סוג הרכבה | Surface Mount |
| Configuration | Single FET |
| Switching Performance | Fast switching, rugged, reliable |
| Packaging | 3000 units per reel (tape and reel) |
תצורת פינים של BSS138L
| פין 1 | Gate — Gate terminal - logic-level control input |
| פין 2 | Drain — Drain terminal - connects to load (standard SOT-23, pin 2 is the wide center lead) |
| פין 3 | Source — Source terminal - connects to ground in low-side switch configurations |
אזור פעולה בטוח (approximate from ratings)
יישומים טיפוסיים
BSS138L מתאים עבור 6 יישוםs: DC-DC Converter Load Switching, Portable and Battery-Powered Product Power Management, 3.3V to 5V Logic Level Shifting, Low-Side Relay and Indicator Load Switching, Printer and Computer Peripheral Power Control, Cellular and Cordless Telephone Circuits.
DC-DC Converter Load Switching
The BSS138L serves as a low-side or load switch in DC-DC converter power trees, where its 50 V rating covers 12 V, 24 V, and intermediate rail architectures with margin. The trench MOSFET technology delivers fast switching transitions that reduce transition losses during PWM chopping and power-path switching. In portable power management, it gates auxiliary rails under microcontroller control, drawing no DC gate current due to the insulated gate structure. The key trade-off is its 3.5 ohm on-resistance: at 200 mA the conduction drop is about 0.7 V, acceptable for switching discrete loads but lossy for high-current paths, where a lower-RDS(on) SOT-23 device should be substituted.
מומלץ
Portable and Battery-Powered Product Power Management
onsemi explicitly lists portable and battery-powered products - computers, printers, PCMCIA cards, cellular and cordless telephones - as typical BSS138L applications. The logic-level gate permits direct drive from 3.3 V battery-management microcontrollers without gate-driver ICs, saving board space and quiescent power. The tiny SOT-23 footprint suits dense handheld layouts, and the 50 V rating provides robust headroom over single-cell and multi-cell battery stacks plus charger transients. Because the gate is capacitive, leakage-driven battery drain is negligible when the switch is static. Designers should size gate series resistance to control inrush and verify RDS(on) at the minimum battery voltage to keep dissipation within the 350 mW package limit.
מומלץ
3.3V to 5V Logic Level Shifting
The BSS138L is a staple of bidirectional open-drain level shifters between 3.3 V and 5 V logic domains (I2C, UART, GPIO). Two BSS138L devices with 10 kOhm pull-up resistors form the classic two-transistor bidirectional shifter: the 3.3 V side gate drive clamps the 5 V side through the MOSFET channel, and vice versa, without direction-control signals. The logic-level threshold ensures full turn-on at 3.3 V, and the low gate capacitance preserves I2C rise-time budgets at standard-mode 100 kHz and fast-mode 400 kHz. Community reports confirm reliable PWM and 3.3 V/5 V operation. Use short traces and verify pull-up sizing against bus capacitance for signal integrity.
מומלץ
Low-Side Relay and Indicator Load Switching
As a low-side switch, the BSS138L drives small signal relays, buzzers, indicator LEDs, and sensor power rails from logic outputs. The 50 V drain rating absorbs the inductive kick of relay coils in concert with a flyback diode, and the rugged trench structure tolerates switching transients per the datasheet's rugged, reliable characterization. At 200 mA it covers most relay coil and LED string loads. Estimated dissipation at full load is about 0.14 W (I2R with 3.5 ohms), comfortably within the 350 mW SOT-23 limit at moderate ambient. Add a gate series resistor of 100 ohms to 1 kOhm to control EMI from fast switching edges and a pulldown to guarantee off-state during MCU reset.
מומלץ
Printer and Computer Peripheral Power Control
Printers, computers, and PC-card peripherals use the BSS138L to gate sensor supplies, stepper-coil hold circuits, and status-indicator power under firmware control, enabling aggressive standby-power reduction. The logic-level input interfaces directly with printer controller SoCs, and the trench technology's fast switching supports PWM dimming of status LEDs and duty-cycled actuator coils. The SOT-23 package withstands the moderate ambient temperatures inside printer chassis while staying within the 350 mW dissipation budget at 200 mA loads. Because peripherals face supply spikes from shared motors and solenoids, the 50 V VDS headroom is valuable. Designers should decouple switched rails locally and route gate drives away from analog sense lines to avoid coupling.
מומלץ
Cellular and Cordless Telephone Circuits
In cellular and cordless telephone hardware, the BSS138L performs battery-path switching, keypad backlight PWM control, and vibration-motor low-side drive, all cited within onsemi's portable-product application scope. The near-zero gate leakage preserves standby battery life, critical in always-on phones, and the logic-level gate connects directly to baseband GPIO operating at 2.8-3.3 V. The small SOT-23 package fits the dense RF board floorplan, and the 50 V rating provides protection margin against battery-charger transients and antenna-adjacent surges. For vibration motors, include a flyback diode and gate pulldown. Verify audible-noise behavior under PWM by choosing switching frequencies above the audible band where possible.
מומלץ
סיכום מוצרים מומלצים
נתוני עזר הנדסיים עבור BSS138L — השוואה, הנחיות תכנון ומידע על תאימות.
מדריך בחירה
השוואה עם חלופות
| פרמטר | מוצר זה | BSS138 | BSS138LT1G | BSS138-7-F | IRLML6344TRPBF |
|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | Diodes Incorporated | Infineon |
| Package | SOT-23-3 | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same | SOT-23-3 - same |
| VDS Max | 50 V | 50 V | 50 V | 50 V | 30 V |
| Continuous Drain Current | 200 mA (Ta) | 220 mA (Ta) | 220 mA class | 220 mA class | ~5 A class |
| Gate Drive | Logic Level (3.3 V / 5 V) | Logic Level | Logic Level | Logic Level | Logic Level (1.8 V capable) |
| Pinout (SOT-23) | G-D-S (1-2-3) | G-D-S - identical | G-D-S - identical | G-D-S - identical | G-D-S - identical |
מבדילים עיקריים
- 50 V drain rating in SOT-23 (לעומתIRLML6344TRPBF)
- Ultra-low cost and multi-source availability (לעומתBSS138-7-F)
- Same-family continuity (לעומתBSS138)
הערות תכנון
Estimated: at the full 200 mA rating and ~3.5 ohm on-resistance, conduction dissipation is I2R = 0.2A x 0.2A x 3.5 ohm = 0.14 W, i.e. 40% of the 350 mW SOT-23 package limit. At elevated ambient temperatures (above ~70C) the allowable dissipation derates further, so apply load derating or select a lower-RDS(on) device (e.g. IRLML6344) when switching currents approach the 200 mA ceiling continuously. Check the datasheet thermal derating curve for your mounting conditions.
Place the BSS138L with short, wide traces on the drain and source to minimize parasitic inductance in fast-switching paths. The SOT-23 center drain lead benefits from an expanded copper pad when any meaningful dissipation is expected; even 20-30 mm2 of extra copper measurably lowers junction temperature. Keep the gate drive trace short and route it away from analog sense lines to prevent capacitive coupling of switching edges. Provide a ground pour connected directly to the source lead.
Do not exceed the 50 V VDS rating: inductive loads (relays, solenoids, motors) can generate transients well above the supply rail, so always include a flyback diode or clamp. Add a 10 kOhm-100 kOhm gate-to-source pulldown so the MOSFET stays off during microcontroller reset or when the driver pin is high-impedance. At 3.3 V gate drive the on-resistance is higher than the 10 V figure - verify the effective RDS(on) from the datasheet characteristic curves rather than assuming 3.5 ohms.
מידע על תאימות
Compliance status not explicitly stated in the provided verified data; the BSS138LT1G Pb-free suffix variant exists in the same family, suggesting lead-free options. Consult the onsemi product page for current RoHS/REACH declarations.
