[{"data":1,"prerenderedAt":236},["ShallowReactive",2],{"component:bss138:en":3},{"component":4,"localizationFallbackIssues":197,"related":198,"equivalentSlugs":235},{"schemaVersion":5,"governance":6,"id":18,"mpn":19,"slug":18,"primaryCategory":20,"manufacturers":21,"lifecycleStatus":23,"shortDescription":24,"deepTechnicalOverview":25,"packages":26,"absoluteMaximums":46,"parametricAttributes":49,"gotchas":152,"datasheetUrl":17,"documentationSources":171,"applicationCircuits":180,"equivalents":185,"mountedOnBoards":186,"seo":187},"1.0.0",{"publication":7,"verification":10,"provenance":15},{"status":8,"publishedDate":9},"published","2026-11-03",{"status":11,"verifiedDate":9,"verifiedBy":12,"checklist":13},"verified","Gemini (independent documentary review against onsemi BSS138\u002FD Rev. 7; verified pinout, SOT-23 package, absolute maximums, electrical parametric limits, gotchas, six-locale localization sidecars, and catalog release validation; owner publication GO, no physical bench signoff)",{"schema":14,"technicalFacts":14,"relationships":14,"sources":14},true,{"sourceUrls":16},[17],"https:\u002F\u002Fwww.onsemi.com\u002Fdownload\u002Fdata-sheet\u002Fpdf\u002Fbss138-d.pdf","bss138","BSS138","power_mosfet",[22],"onsemi","active","onsemi BSS138 N-channel logic-level MOSFET in SOT-23 (CASE 318-08), G-S-D pinout; absolute VDSS limit 50 V and continuous ID limit 220 mA at TA = 25°C.","The BSS138 is an industry-standard small-signal N-channel enhancement-mode logic-level field-effect transistor produced by onsemi (datasheet BSS138\u002FD, Rev. 7, April 2024). Housed in an industry-standard surface-mount SOT-23 package (TO-236AB \u002F CASE 318-08), the device features a G-S-D pinout: Pin 1 Gate (G), Pin 2 Source (S), and Pin 3 Drain (D). Absolute maximum ratings at TA = 25°C specify a drain-source breakdown voltage VDSS of 50V, continuous drain-gate voltage VDGR of 50V (RGS \u003C= 1 MΩ), continuous gate-source voltage VGSS of ±20V (non-repetitive peak ±40V for tp \u003C 50 µs), continuous drain current ID of 220mA, pulsed drain current IDM of 880mA, and total device dissipation PD of 360mW (derating 2.8 mW\u002F°C above 25°C; thermal resistance junction-to-ambient RthetaJA = 350°C\u002FW on minimum pad). Electrical characteristics guarantee minimum drain-source breakdown voltage BVDSS = 50V tested at VGS = 0V, ID = 250 µA. Gate threshold voltage VGS(th) spans 0.8V min, 1.3V typ, to 1.5V max at VDS = VGS, ID = 1.0 mA, representing the onset of channel conduction. Static drain-source on-resistance RDS(on) is guaranteed at 1.4 Ω typ, 3.5 Ω max at VGS = 10V, ID = 0.22 A, and 1.9 Ω typ, 6.0 Ω max at VGS = 4.5V, ID = 0.22 A. Switching speeds are rapid, with typical turn-on delay td(on) = 2.5 ns (20 ns max), rise time tr = 9 ns (20 ns max), turn-off delay td(off) = 20 ns (50 ns max), and fall time tf = 7 ns (20 ns max) under VDD = 30V, ID = 0.22 A, VGS = 10V, and RGEN = 50 Ω. Input capacitance Ciss is 27 pF typ (50 pF max) at VDS = 25V, VGS = 0V, f = 1.0 MHz. The integrated body diode specifies a maximum continuous forward source current IS of 0.22 A and forward voltage VSD of 0.8V typ, 1.4V max at VGS = 0V, IS = 0.22 A.",[27],{"packageType":28,"pinCount":29,"thermalResistanceThetaJA":30,"pins":31},"SOT-23",3,350,[32,39,43],{"pinNumber":33,"pinName":34,"electricalType":35,"isFiveVoltTolerant":36,"internalPull":37,"description":38},1,"G","passive",false,"none","Gate terminal (pin 1, bottom-left lead of SOT-23 \u002F CASE 318-08; high-impedance gate input, absolute VGS limit ±20V continuous, ±40V non-repetitive peak for tp \u003C 50 µs)",{"pinNumber":40,"pinName":41,"electricalType":35,"isFiveVoltTolerant":36,"internalPull":37,"description":42},2,"S","Source terminal (pin 2, bottom-right lead of SOT-23 \u002F CASE 318-08; common reference terminal for gate and drain potentials)",{"pinNumber":29,"pinName":44,"electricalType":35,"isFiveVoltTolerant":36,"internalPull":37,"description":45},"D","Drain terminal (pin 3, top-center lead of SOT-23 \u002F CASE 318-08; absolute VDSS limit 50V, continuous ID limit 220 mA at TA = 25°C)",{"storageTempMinC":47,"storageTempMaxC":48},-55,150,[50,57,64,70,76,83,89,95,101,106,111,118,122,125,129,133,138,142,148],{"symbol":51,"name":52,"typicalValue":53,"minValue":54,"unit":55,"testCondition":56},"BVDSS","Drain-Source Breakdown Voltage","—",50,"V","VGS = 0 V, ID = 250 µA, TJ = 25°C",{"symbol":58,"name":59,"typicalValue":60,"minValue":61,"maxValue":62,"unit":55,"testCondition":63},"VGS_th","Gate-Threshold Voltage",1.3,0.8,1.5,"VDS = VGS, ID = 1.0 mA, TJ = 25°C",{"symbol":65,"name":66,"typicalValue":53,"maxValue":67,"unit":68,"testCondition":69},"IDSS","Zero Gate Voltage Drain Current",0.5,"µA","VDS = 50 V, VGS = 0 V, TJ = 25°C",{"symbol":71,"name":72,"typicalValue":53,"maxValue":73,"unit":74,"testCondition":75},"IGSS","Gate-Body Leakage Current",100,"nA","VGS = ±20 V, VDS = 0 V, TJ = 25°C",{"symbol":77,"name":78,"typicalValue":79,"maxValue":80,"unit":81,"testCondition":82},"RDS_on_10V","Drain-Source On-Resistance at 10V",1.4,3.5,"Ω","VGS = 10 V, ID = 0.22 A, TJ = 25°C",{"symbol":84,"name":85,"typicalValue":86,"maxValue":87,"unit":81,"testCondition":88},"RDS_on_4_5V","Drain-Source On-Resistance at 4.5V",1.9,6,"VGS = 4.5 V, ID = 0.22 A, TJ = 25°C",{"symbol":90,"name":91,"typicalValue":30,"minValue":92,"unit":93,"testCondition":94},"gFS","Forward Transconductance",170,"mS","VDS = 10 V, ID = 0.22 A, TJ = 25°C",{"symbol":96,"name":97,"typicalValue":98,"maxValue":54,"unit":99,"testCondition":100},"Ciss","Input Capacitance",27,"pF","VDS = 25 V, VGS = 0 V, f = 1.0 MHz, TJ = 25°C",{"symbol":102,"name":103,"typicalValue":104,"maxValue":105,"unit":99,"testCondition":100},"Coss","Output Capacitance",11,25,{"symbol":107,"name":108,"typicalValue":109,"maxValue":110,"unit":99,"testCondition":100},"Crss","Reverse Transfer Capacitance",4,8,{"symbol":112,"name":113,"typicalValue":114,"maxValue":115,"unit":116,"testCondition":117},"td_on","Turn-On Delay Time",2.5,20,"ns","VDD = 30 V, ID = 0.22 A, VGS = 10 V, RGEN = 50 Ω, TJ = 25°C",{"symbol":119,"name":120,"typicalValue":121,"maxValue":115,"unit":116,"testCondition":117},"tr","Rise Time",9,{"symbol":123,"name":124,"typicalValue":115,"maxValue":54,"unit":116,"testCondition":117},"td_off","Turn-Off Delay Time",{"symbol":126,"name":127,"typicalValue":128,"maxValue":115,"unit":116,"testCondition":117},"tf","Fall Time",7,{"symbol":130,"name":131,"typicalValue":53,"maxValue":54,"unit":55,"testCondition":132},"VDSS","Absolute Maximum Drain-Source Voltage","TA = 25°C",{"symbol":134,"name":135,"typicalValue":53,"maxValue":136,"unit":137,"testCondition":132},"ID_cont","Absolute Maximum Continuous Drain Current",220,"mA",{"symbol":139,"name":140,"typicalValue":53,"maxValue":141,"unit":137,"testCondition":132},"IDM","Absolute Maximum Pulsed Drain Current",880,{"symbol":143,"name":144,"typicalValue":53,"maxValue":145,"unit":146,"testCondition":147},"PD","Absolute Maximum Total Device Dissipation",360,"mW","TA = 25°C; derate 2.8 mW\u002F°C above 25°C",{"symbol":149,"name":150,"typicalValue":61,"maxValue":79,"unit":55,"testCondition":151},"VSD","Body Diode Forward Voltage","VGS = 0 V, IS = 0.22 A, TJ = 25°C",[153,158,162,167],{"title":154,"severity":155,"description":156,"mitigationStrategy":157},"Source Versus Drain Orientation in Bidirectional I2C Level Shifter Circuits","critical","In classic bidirectional I2C logic level shifter circuits (NXP AN10441), the MOSFET source terminal must be connected to the lower-voltage supply rail domain (e.g., 3.3V) with its gate tied to the 3.3V supply, while the drain terminal faces the higher-voltage bus domain (e.g., 5V). Because the enhancement-mode MOSFET contains an intrinsic body diode directed from source to drain, reversing source and drain places the anode at the higher 5V rail and cathode at the 3.3V rail. This permanently forward-biases the internal body diode whenever the 3.3V side is lower, causing unconstrained current leakage from the 5V rail into the 3.3V rail and clamping the high-voltage bus down.","Orient the BSS138 strictly with Source (pin 2) on the lower-voltage side (VCC_low) and Drain (pin 3) on the higher-voltage side (VCC_high). Gate (pin 1) connects directly to VCC_low. Provide external pull-up resistors on both sides to establish correct quiescent high states.",{"title":159,"severity":155,"description":160,"mitigationStrategy":161},"Small-Signal On-Resistance (RDS(on) up to 6.0 Ω) Precludes Power Load Switching","The BSS138 is designed specifically for small-signal logic level shifting and high-speed digital switching, not power load switching. Datasheet BSS138\u002FD specifies static on-resistance of up to 3.5 Ω at VGS = 10V and up to 6.0 Ω at VGS = 4.5V (at ID = 0.22 A). Passing 150 mA through a 6.0 Ω channel produces a 0.9V voltage drop across the transistor and generates 135 mW of power dissipation. In a tiny SOT-23 package with thermal resistance RthetaJA = 350°C\u002FW on minimum pad, this raises the junction temperature by over 47°C above ambient, causing thermal stress.","Restrict BSS138 switching to low-current digital signals, communication lines, and pull-up networks (ID \u003C 50 mA). For power switching, motor control, or relay driving above 100 mA, select a low-RDS(on) power MOSFET such as IRLZ44N, 2N7000, or a dedicated modern power TrenchFET.",{"title":163,"severity":164,"description":165,"mitigationStrategy":166},"Sub-3.3V Logic Drive and Lack of Guaranteed Low-Voltage Gate Overdrive","warning","Although the gate threshold voltage VGS(th) is specified between 0.8V and 1.5V (tested at ID = 1.0 mA), the threshold represents only the initial onset of channel conduction. The onsemi BSS138 datasheet provides guaranteed RDS(on) specifications only at VGS = 10V (\u003C= 3.5 Ω) and VGS = 4.5V (\u003C= 6.0 Ω); it does not guarantee on-resistance at 1.8V, 2.5V, or 3.3V gate drive. When used to translate signals between 1.8V and 3.3V logic systems, gate overdrive (VGS - VGS(th)) can be as small as 0.3V on worst-case parts, leading to significantly higher channel resistance and slow signal rise times on capacitive I2C buses.","For 1.8V or 2.5V logic domains, calculate bus RC time constants assuming a higher effective channel resistance (~15–30 Ω). If rise times violate I2C fast-mode (400 kHz) bus specifications, reduce pull-up resistance values accordingly, or use dedicated sub-1.8V translator ICs (such as PCA9306 or TXS0102).",{"title":168,"severity":164,"description":169,"mitigationStrategy":170},"Parasitic Body Diode Conduction During Negative Voltage Ringing or Rail Sequencing","The integral body diode between source (anode) and drain (cathode) has a forward conduction voltage of 0.8V typ, 1.4V max. If bus lines experience inductive overshoot, ground bounce, or if the higher-voltage supply rail is unpowered while the lower-voltage side remains active, current can conduct parasitically through the body diode. In power-down scenarios where the 5V supply is collapsed to ground, pulling a 3.3V line low will not conduct, but raising it high may backfeed into the collapsed 5V bus through the pull-up and channel.","Verify power rail sequencing in multi-voltage embedded systems. Ensure supply decoupling capacitors discharge safely and avoid situations where signals are driven into unpowered IC pins. When driving inductive loads or long cables, add Schottky clamp diodes to suppress negative ground ringing.",[172],{"title":173,"url":17,"type":174,"authority":175,"publisher":22,"documentNumber":176,"revision":177,"releaseDate":178,"language":179},"BSS138 N-Channel Logic Level Enhancement Mode Field Effect Transistor","datasheet","primary","BSS138\u002FD","Rev. 7","2024-04","EN",[181],{"title":182,"schematicSlug":183,"topology":184},"BSS138 Bidirectional I2C 3.3V to 5V Level Shifter","bss138-bidirectional-i2c-level-shifter","Bidirectional N-channel MOSFET voltage level translator with gate clamped to 3.3V, source on 3.3V bus, and discrete pull-ups.",[],[],{"canonicalUrl":188,"metaTitle":189,"metaDescription":190,"primarySearchCluster":191,"structuredDataSchema":196},"https:\u002F\u002Fcircuitbase.tech\u002Fcomponent\u002Fbss138","BSS138 N-Channel MOSFET Pinout, Datasheet & Specs | CircuitBase","onsemi BSS138 SOT-23 N-channel MOSFET pinout (G-S-D), 50V 220mA ratings, bidirectional I2C level shifting gotchas, and switching characteristics.",[192,193,194,195],"bss138 pinout","bss138 mosfet datasheet","bss138 sot-23","bss138 logic level converter","Product",null,[199,208,218,227],{"id":200,"slug":200,"mpn":201,"primaryCategory":20,"manufacturers":202,"shortDescription":203,"packages":204,"packageTypes":207,"voltage":-1},"2n7000","2N7000",[22],"onsemi 2N7000 N-channel MOSFET in TO-92 (CASE 135AN), S-G-D pinout; absolute VDSS limit 60 V and continuous ID limit 200 mA at TC = 25°C.",[205],{"packageType":206,"pinCount":29},"TO-92",[206],{"id":209,"slug":209,"mpn":210,"primaryCategory":20,"manufacturers":211,"shortDescription":213,"packages":214,"packageTypes":217,"voltage":-1},"irlz44n","IRLZ44NPbF",[212],"Infineon Technologies","Infineon IRLZ44NPbF N-channel logic-level power MOSFET in TO-220AB, with G-D-S pinout and a drain-connected tab; on-resistance is specified under separate 4 V, 5 V and 10 V gate-drive test conditions.",[215],{"packageType":216,"pinCount":29},"TO-220AB",[216],{"id":219,"slug":219,"mpn":220,"primaryCategory":221,"manufacturers":222,"shortDescription":223,"packages":224,"packageTypes":226,"voltage":-1},"2n3904","2N3904","bipolar_transistor",[22],"General-purpose small-signal NPN silicon bipolar junction transistor in a TO-92 package with E-B-C pinout, featuring 40V VCEO and 200mA IC absolute maximum ratings.",[225],{"packageType":206,"pinCount":29},[206],{"id":228,"slug":228,"mpn":229,"primaryCategory":221,"manufacturers":230,"shortDescription":231,"packages":232,"packageTypes":234,"voltage":-1},"2n3906","2N3906",[22],"General-purpose small-signal PNP silicon bipolar junction transistor in a TO-92 package with E-B-C pinout, featuring 40V VCEO and 200mA IC absolute maximum ratings.",[233],{"packageType":206,"pinCount":29},[206],{},1793836421828]