BC817-40 - 45V 500mA NPN Transistor SOT-23 | Nexperia
MPN: BC817-40 ✓ Hoạt độngBC817-40 Tóm tắt
An NPN BJT is a three-terminal semiconductor device in which a small base current controls a much larger collector current; it belongs to the bipolar transistor family within discrete semiconductors. The BC817 series occupies the medium-power small-signal segment - more current than a BC847 (100 mA) yet in the same miniature SOT-23 footprint, sitting between signal-level transistors and dedicated switching MOSFETs.
Key features include a transition frequency (fT) of 100 MHz, VCEO of 45 V, VCBO of 50 V, VEBO of 5 V, and a low collector-emitter saturation voltage typically below 700 mV at 500 mA. The complementary PNP counterpart is the BC807-40, which uses an identical pinout with reversed polarity, enabling paired push-pull output stages in audio and DC-DC converter circuits.
The device is built using an epitaxial planar die process in a SOT-23 (TO-236AB) package, the industry-standard 3-pin surface-mount outline measuring approximately 2.9 mm x 1.3 mm with a JEDEC TO-236 registration. The plastic encapsulation carries an MSL-1 moisture sensitivity rating, allowing direct reflow without prior bake-out.
Typical applications include switching circuits, AF driver stages, generic interface level-shifters, MOSFET gate drivers, relay/solenoid drivers, and DC-DC converter synchronised rectifiers. The -40 hFE bin is especially useful where high gain is needed without cascading a second transistor.
When designing with the BC817-40, place a base series resistor to limit base current during turn-off transients, and respect the 310 mW power dissipation limit at 25 C by derating approximately 2.5 mW per degree Celsius above that point.
This page consolidates distributor pricing, pin-compatible drop-in alternatives, and application guidance not found in the standalone datasheet.
Bộ thay thế dễ dàng lắp đặt cho BC817-40 — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với BC817-40 (cùng hình factor và footprint) — khác nhau ở Package, Transistor Type, MSL Level, Continuous Collector Current (IC), RoHS Status.
BC817-40,215
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →BC817-40-7-F
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
BC817-40-TP
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MMBTA06
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
BCW66H
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MMBTA05
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
BCX19
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
BC817-40 Tỷ lệ tối đa & tính chất điện
| Kiểu transitor | NPN Bipolar Junction Transistor (BJT) |
| Hộp | SOT-23 (TO-236AB), 3 pins |
| N Nap-Emit (Vceo) | 45 V |
| N Nap (Vcbo) | 50 V |
| N Nap-cơ sở (Vebo) | 5 V |
| Continuous Collector Current (IC) | 500 mA |
| Total Power Dissipation (Ptot) | 310 mW |
| DC Current Gain (hFE) - -40 bin | 250 to 600 (at 100 mA, 1 V) |
| Tần số chuyển đổi (ft) | 100 MHz |
| Collector-Emitter Saturation Voltage (VCEsat) | 700 mV max (at 500 mA, 50 mA base) |
| Nhiệt độ mối nối hoạt động | -65 C to +150 C |
| Kiểu lắp đặt | Surface Mount |
| Cấp MSL | 1 |
| Trạng thái RoHS | Compliant |
| Complementary PNP Part | BC807-40 |
Cấu hình chân BC817-40
| Chân 1 | Base — Control input; base current modulates collector current |
| Chân 2 | Emitter — Current returns to ground or low-side reference |
| Chân 3 | Collector — Connects to load or supply rail (load-side for low-side switching) |
Ứng dụng tiêu biểu
BC817-40 phù hợp cho 6 Áp dụngs: Relay and Solenoid Driver, LED Driver and Indicator Switch, Logic Level Shifter (3.3V to 12V/24V), MOSFET Gate Driver Pre-Driver, AF Amplifier Driver Stage, Synchronous Rectifier in DC-DC Converters.
Relay and Solenoid Driver
The BC817-40's 500 mA continuous collector current comfortably exceeds the 70 to 150 mA typical pull-in current of signal relays, making it a textbook low-side switch for 5 V/12 V/24 V coil drive. The 45 V VCEO provides 2x headroom over a 24 V rail, and the 250 hFE minimum lets a 3.3 V GPIO deliver 10 mA into the base to fully saturate the device. Place a 1N4148 flyback diode across the coil; this is critical because the inductive kick otherwise destroys the transistor.
Được đề xuất
LED Driver and Indicator Switch
The BC817-40 is widely used as a low-side switch for LED strings up to 500 mA total current. With a typical hFE of 400 and 1.5 mA base current, the transistor saturates at ~100 mV VCEsat, dissipating minimal power and avoiding the need for a driver MOSFET. The 45 V VCEO also supports high-side switching of multi-LED backlight chains driven from a 12 V or 24 V rail.
Được đề xuất
Logic Level Shifter (3.3V to 12V/24V)
The BC817-40 is a classic level translator between 3.3 V microcontroller GPIO and 5 V, 12 V, or 24 V peripheral rails. With 45 V VCEO and a 250 hFE minimum, the transistor interfaces cleanly from low-voltage CMOS logic to industrial bus voltages. The 100 MHz fT ensures edge transitions remain sub-microsecond, suitable for SPI, I2C, and UART re-buffering into RS-485/RS-232 transceivers.
Được đề xuất
MOSFET Gate Driver Pre-Driver
In DC-DC converters and motor drives, the BC817-40 acts as a totem-pole pre-driver for power MOSFET gates that require 10 to 50 nC of gate charge. The 500 mA collector current and 100 MHz fT easily deliver the peak gate-drive current during switching transitions, while the SOT-23 footprint keeps the driver compact. Pair with a complementary BC807-40 (PNP) for symmetric push-pull drive.
Được đề xuất
AF Amplifier Driver Stage
The BC817-40's 100 MHz transition frequency and 250 to 600 hFE range make it suitable as a small-signal AF pre-amplifier or driver stage in audio circuits. The -40 bin provides high sensitivity, enabling the stage to drive headphones, small speakers through a complementary pair, or buffer line-level signals into a power amplifier input. The 45 V VCEO allows operation from +/-15 V rails.
Được đề xuất
Synchronous Rectifier in DC-DC Converters
In low-power buck converters below 500 mA output, the BC817-40 can be used as a synchronous rectifier (low-side switch) replacing a Schottky diode for improved efficiency. With 700 mV VCEsat max at full load, conduction loss is roughly half that of an equivalent Schottky. The fast 100 MHz fT minimises dead-time losses when paired with a complementary high-side switch in continuous-conduction mode.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho BC817-40 — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | BC817-40,215 | BC817-40-7-F | BC817-40-TP | MMBTA06 | BCW66H |
|---|---|---|---|---|---|---|
| Package | SOT-23 (TO-236AB) | SOT-23 (TO-236AB) - same | SOT-23 (TO-236AB) - same | SOT-23 (TO-236AB) - same | SOT-23 (TO-236AB) - same | SOT-23 (TO-236AB) - same |
| Brand | Nexperia | Nexperia | Diodes Incorporated | MCC | onsemi | Nexperia |
| VCEO (Collector-Emitter Voltage) | 45 V | 45 V | 45 V | 45 V | 80 V | 45 V |
| Continuous Collector Current (IC) | 500 mA | 500 mA | 500 mA | 500 mA | 500 mA | 800 mA |
| DC Current Gain (hFE) - Min | 250 | 250 | 250 | 250 | 100 | 250 |
| Transition Frequency (fT) | 100 MHz | 100 MHz | 100 MHz | 100 MHz | 100 MHz | 100 MHz |
| Power Dissipation (Ptot) | 310 mW | 310 mW | 310 mW | 310 mW | 350 mW | 350 mW |
| Polarity | NPN | NPN | NPN | NPN | NPN | NPN |
| Qty-1 Unit Price (USD) | $0.08 | $0.08 | $0.07 | $0.04 | $0.05 | $0.09 |
Bảo phân biệt quan trọng
- Highest hFE bin in the BC817 family (vsBC817-25)
- Industry-standard 45 V/500 mA envelope (vsMMBTA06)
- Multi-source second-source availability (vsProprietary transistors)
Ghi chú thiết kế
Estimated: At maximum ratings of 500 mA collector current and 45 V VCEO, instantaneous power could theoretically reach 22.5 W, but the 310 mW continuous dissipation limit (at 25 C ambient, with no heatsink) bounds real-world operation. Derate by approximately 2.5 mW per degree Celsius above 25 C - at 100 C ambient the limit drops to ~187 mW. For switching applications at 100 mA or less, thermal performance is rarely an issue; for sustained 300 to 500 mA loads use a copper pour of at least 1 cm squared on the collector pad.
Three recurring pitfalls with the BC817-40: (1) forgetting the flyback diode across inductive loads - a relay coil without a 1N4148 across it can produce 100+V transients that exceed the 45 V VCEO and destroy the transistor; (2) driving the base with insufficient current - designs assuming hFE = 600 may saturate but those targeting the minimum hFE = 250 must supply at least IC/250 base current; (3) confusing pinout - on the SOT-23 outline, the base is pin 1, emitter pin 2, collector pin 3, which differs from some larger packages (TO-92 has C-B-E order).
SOT-23 thermal performance depends almost entirely on the copper pad connected to pin 3 (collector). For sustained loads above 200 mA, expand the collector pad to at least 25 mm squared of 2 oz copper on both PCB layers stitched with thermal vias. Place the base series resistor within 5 mm of pin 1 to minimise parasitic inductance that can cause ringing during fast transients.
Thông tin tuân thủ
RoHS and REACH compliant per Nexperia product page. Not AEC-Q100 qualified for automotive - consult the manufacturer's automotive-grade portfolio if required. Lead-free reflow-compatible per JEDEC J-STD-020.
