BC817-40-SNR - 45V 500mA NPN Transistor SOT-23 | Nexperia
Teilenummer: BC817-40-SNR ✓ Aktiv| Menge | Stückpreis | Gesamt |
|---|---|---|
| 1 | $0.16 | $0,16 |
| 10 | $0.12 | $1,20 |
| 100 | $0.08 | $8,00 |
| 500 | $0.06 | $30,00 |
| 1.000 | $0.045 | $45,00 |
| 3.000 | $0.035 | $105,00 |
BC817-40-SNR Übersicht
An NPN bipolar transistor is a three-terminal semiconductor device in which a small base current controls a much larger collector current. The BC817 series belongs to the BJT hierarchy: bipolar transistor -> small-signal transistor -> general-purpose amplifier/switch -> discrete semiconductor. NPN transistors are the most common BJT polarity, used for low-side switching, signal amplification, and driver stages where the emitter is grounded and the load is tied to the positive supply.
Key specifications include a collector-emitter breakdown voltage (VCEO) of 45 V, collector current (IC) of 500 mA continuous, total power dissipation (Ptot) of 250 mW, and a transition frequency (fT) of 100 MHz. The DC current gain is binned: BC817-16 (110-250 hFE), BC817-25 (175-400 hFE), and BC817-40 (250-630 hFE). The PNP complement is BC807-50 (same hFE bin convention).
Architecturally, the BC817-40 uses an epitaxial planar NPN die in a plastic SOT-23 housing with three gull-wing leads (Base, Collector, Emitter). The exposed tab on the package body serves as a thermal pad and is connected to the collector. The high fT of 100 MHz supports RF and high-speed switching applications, while the 45 V VCEO rating permits direct interfacing to 24 V industrial buses and 12 V automotive rails without additional protection.
Typical applications include low-side switching for relays, LEDs, and solenoids; general-purpose amplification in audio and instrumentation circuits; load drivers for MOSFET gate drivers; oscillator and timer circuits; and interface circuits between logic levels and higher-voltage loads. The BC817-40 is widely used in consumer electronics, industrial controls, and automotive subsystems.
When designing with this device, observe the 250 mW power dissipation limit at 25 C ambient. For switching inductive loads such as relays or solenoids, place a flyback diode across the load to clamp the back-EMF and protect the transistor. Ensure base current is properly limited via a series resistor to avoid driving the transistor into saturation excessively.
This page synthesizes distributor pricing, drop-in alternatives, and engineering design notes drawn from the Nexperia BC817-40 datasheet, going beyond what any single distributor listing provides.
Drop-in-Alternativen für BC817-40-SNR – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit BC817-40-SNR (gleiche Bauform und Footprint) – abweichend in MSL Level, Package, Transistor Type.
Schnellvergleichstool – Wählen Sie Alternativbauteile für den Direktvergleich:
BC817-40
✅ Drop-In✓ Auf Lager
$0.018 / Stück
Datenblatt ansehen →BC817-40-Q
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
BC817-40-7-F
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
BC817-40-G
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
MMBT6428
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
BCX19
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
BC817-40-SNR Grenzwerte & elektrische Eigenschaften
| Transistortyp | NPN |
| Gehäuse | SOT-23 (TO-236AB) |
| Montageart | Surface Mount |
| Kollektor-Emitter-Spannung (Vceo) | 45 V |
| Kollektor-Basis-Spannung (Vcbo) | 50 V |
| Emitter-Basis-Spannung (Vebo) | 5 V |
| Continuous Collector Current (IC) | 500 mA |
| Peak Collector Current (ICM) | 1000 mA |
| Verlustleistung (Ptot) | 250 mW |
| Übergangsfrequenz (ft) | 100 MHz |
| DC Current Gain (hFE) | 250 to 630 (at VCE=2V, IC=100mA) |
| hFE Bin | -40 (high gain bin) |
| Betriebstemperatur | -65 C to +150 C |
| Pin Configuration | 1-Base, 2-Emitter, 3-Collector (SOT-23 standard) |
| RoHS-Status | Compliant |
| MSL-Level | MSL 1 |
| Complement (PNP) | BC807-40 |
| Packaging Suffix | /SNR (SOT-23, Tape and Reel, 3000 pcs) |
BC817-40-SNR Pin-Konfiguration
| Pin 1 | Base — Control terminal - base current drives collector current with hFE gain |
| Pin 2 | Emitter — Current output / ground reference terminal |
| Pin 3 | Collector — Current input / load connection terminal |
Typische Anwendungen
BC817-40-SNR ist geeignet für 6 Anwendungs: Low-Side Relay Driver, LED Indicator Driver, General-Purpose Signal Amplifier, MOSFET Gate Driver, Logic Level Shifter, Oscillator and Timer Circuits.
Low-Side Relay Driver
The Nexperia BC817-40-SNR is widely used as a low-side driver for 5V, 12V, and 24V relays in industrial control boards. Its 45V VCEO rating exceeds the supply rails by 2x or more, providing robust margin against inductive kickback. The 500mA continuous collector current handles most signal relays; for larger contactors above 1A, use a Darlington like the TIP120 or a MOSFET. The high hFE bin of 250-630 (BC817-40) means a base current of just 1-2mA is enough to fully saturate the transistor at 500mA collector current, allowing direct drive from 3.3V or 5V microcontroller GPIO pins through a 1k-2.2k base resistor. Add a 1N4148 flyback diode across the relay coil to clamp the inductive spike and protect the transistor's VCEO rating from exceeding 45V during turn-off.
Empfohlen
LED Indicator Driver
The BC817-40-SNR's 45V VCEO and 500mA collector current make it ideal for driving LED strings from logic-level control signals. A typical circuit uses a microcontroller GPIO pin driving the base through a resistor (calculated as (V_GPIO - V_BE) / I_B), with the LED and current-limiting resistor connected between V+ (up to 45V) and the collector. The 250-630 hFE bin ensures low base current draw from the microcontroller. For PWM dimming, the BC817-40-SNR's 100MHz transition frequency is well above typical PWM frequencies (1kHz-100kHz), so switching losses are negligible. This topology is preferred over high-side drivers when the LED common anode is grounded, simplifying PCB routing.
Empfohlen
General-Purpose Signal Amplifier
The BC817-40-SNR serves as a low-cost general-purpose amplifier for audio preamp stages, sensor signal conditioning, and instrumentation circuits. Its 100MHz transition frequency and low noise floor support audio bandwidth applications up to 20kHz with headroom. The high hFE bin (250-630) provides high input impedance at the base, which is advantageous when interfacing with high-impedance sensors like piezoelectric pickups or photodiodes. Common emitter and emitter follower topologies are both supported. For differential pairs, use matched pairs from the same hFE bin. The 45V VCEO allows large signal swings with supply rails up to +/-20V in dual-supply amplifier designs.
Empfohlen
MOSFET Gate Driver
The BC817-40-SNR is frequently used as a low-side gate driver for small-signal MOSFETs in DC-DC converters, motor control circuits, and PWM applications. Its 500mA peak current capability can source/sink the gate charge of small MOSFETs (e.g., 2N7002) in tens of nanoseconds, making it suitable for switching frequencies up to several hundred kHz. The 45V VCEO rating exceeds the gate drive voltage of standard MOSFETs (typically 10V-20V). For totem-pole driver topologies using both NPN and PNP transistors (e.g., BC817-40 + BC807-40), the matched hFE bins simplify the design. The BC817-40-SNR can also drive the gate of small IGBTs in low-power inverter circuits.
Empfohlen
Logic Level Shifter
The BC817-40-SNR enables level shifting between 3.3V microcontrollers and 5V or 12V peripheral logic. A common configuration uses the BC817-40 as an open-collector inverter: the emitter is grounded, the base receives the 3.3V signal through a resistor, and the collector pulls up to the target logic voltage (5V or 12V). The 45V VCEO supports shifts up to 24V industrial buses. The high hFE bin (250-630) means a base resistor of 10k-47k is sufficient at 3.3V, minimizing current draw from the microcontroller GPIO. For bidirectional level shifting (e.g., I2C buses), use the BC817-40 in conjunction with a PNP transistor like the BC807-40 in a dual-transistor active pull-up configuration.
Empfohlen
Oscillator and Timer Circuits
The BC817-40-SNR is a standard component in classic oscillator and timer circuits such as the astable multivibrator, blocking oscillator, and relaxation oscillator. Its 100MHz transition frequency supports oscillation frequencies from sub-Hz to several MHz, depending on the RC timing components. The high hFE bin (250-630) ensures reliable startup and stable oscillation amplitude. The 45V VCEO rating permits operation with supply voltages up to 30V in astable multivibrator circuits, useful for high-voltage timing applications. The matched PNP complement BC807-40 is ideal for complementary astable multivibrator designs requiring symmetric output waveforms.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für BC817-40-SNR – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | BC817-40 | BC817-40-Q | BC817-40-7-F | BC817-40-G | MMBT6428 | BCX19 |
|---|---|---|---|---|---|---|---|
| Brand | Nexperia | Nexperia | Nexperia | Diodes Incorporated | Diodes Incorporated | onsemi | onsemi |
| Package | SOT-23 (TO-236AB) | SOT-23 (TO-236AB) - same | SOT-23 (TO-236AB) - same | SOT-23 - same | SOT-23 - same | SOT-23 - same | SOT-23 - same |
| VCEO (Max) | 45 V | 45 V | 45 V | 45 V | 45 V | 50 V | 45 V |
| Continuous Collector Current | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA | 200 mA | 500 mA |
| hFE Bin | 250-630 | 250-630 | 250-630 | 250-630 | 250-630 | 250-650 | 100-630 (full BC817 range) |
| Automotive Grade | No (standard grade) | No | Yes (AEC-Q101) | No | No | No | No |
| Pricing (Qty 1, as of 2026-10-13) | $0.16 | ~$0.12 (typically lower than /SNR) | ~$0.25 (automotive grade premium) | ~$0.10 | ~$0.10 | ~$0.15 | ~$0.10 |
Wichtigste Unterscheidungsmerkmale
- Higher hFE bin (250-630) enables lower base current drive (vs. BC817-25 (175-400 hFE))
- Automotive grade option (BC817-40-Q) is drop-in compatible (vs. BC817-40-7-F (Diodes Incorporated, non-automotive))
- Higher continuous collector current than MMBT6428 (vs. MMBT6428 (onsemi, SOT-23))
- Matched PNP complement (BC807-40) for symmetric designs (vs. MMBT6428 (no closely matched PNP in same package))
Designhinweise
The BC817-40-SNR is rated for 250 mW power dissipation at 25 C ambient, derating linearly to 0 mW at 150 C. For continuous operation above 100 mA collector current, calculate the actual dissipation (VCE x IC) and verify it stays within the SOT-23 thermal budget. The SOT-23 thermal resistance (theta_JA) is approximately 500 C/W on a standard JEDEC test board. At 100 mA continuous with VCE=5V (500 mW dissipation), the junction would exceed 150 C - use pulsed operation or upgrade to a SOT-223 package (e.g., BCP56).
When switching inductive loads (relays, solenoids, motors), always place a flyback diode (e.g., 1N4148 or 1N4001) across the load in reverse bias. Without this diode, the inductive kickback at turn-off can generate hundreds of volts, easily exceeding the 45 V VCEO rating and destroying the transistor. The diode should be rated for at least the load current and reverse voltage equal to the supply voltage. For AC loads or H-bridge configurations, use TVS diodes or Zener clamping.
For reliable SOT-23 SMT assembly, use pad dimensions per IPC-7351 nominal land pattern (SOT-23 standard: 0.95mm x 0.65mm pads with 0.4mm gap). Apply no-clean solder paste (SAC305) with a stencil thickness of 100-150 microns. The SOT-23 is suitable for both reflow soldering (peak temperature 245-260 C, 30-60 seconds above 217 C) and selective wave soldering. Avoid excessive thermal mass on the emitter or collector pads that could cause tombstoning during reflow.
When using the BC817-40-SNR in high-frequency switching applications (above 1 MHz), keep the base-emitter trace short to minimize parasitic inductance. A 10 nH parasitic inductance at the base can cause significant ringing and potential oscillation in high-gain configurations. Place a small base-emitter resistor (1k-10k) to dampen any tendency toward parasitic oscillation. For RF applications above 100 MHz, consider the package parasitic capacitance (typically 4-5 pF between pins) and verify signal integrity with TDR or VNA measurements.
Compliance-Informationen
RoHS compliant per Nexperia product page. Not AEC-Q100 qualified in standard /SNR variant - choose BC817-40-Q for AEC-Q101 automotive qualification. Lead-free (Pb-free) terminations, halogen-free molding compound.
