Nexperia USA Inc. BC817-40/SNR

Overview

BC817-40/SNR from Nexperia is a 45 V, 500 mA NPN general-purpose transistor in SOT23 (TO-236AB) package, optimized for switching and linear amplification with h_FE = 250–600 at V_CE = 1 V, I_C = 100 mA, and T_amb = 25 °C. It delivers low V_CE(sat) ≤ 700 mV at I_C = 500 mA / I_B = 50 mA and supports peak collector current up to 1 A for pulse widths ≤ 1 ms - used in DC-DC converter bias circuits, microcontroller I/O interface buffers, and relay drivers.

For engineers reviewing the BC817-40/SNR datasheet, BC817-40/SNR pinout, BC817-40/SNR application, or BC817-40/SNR equivalent, this page provides verified pin assignments, thermal derating curves, h_FE distribution data across temperature, saturation voltage behavior at high I_C, and validated alternatives for gain-matched replacement in cost-sensitive consumer and industrial control designs.

Technical Context

This NPN bipolar junction transistor operates in active, saturation, and cutoff regions with defined absolute maximum ratings: V_CEO = 45 V, I_C = 500 mA continuous, and P_tot = 250 mW on standard FR4 PCB. Its h_FE range of 250–600 enables stable current amplification in emitter-follower and common-emitter configurations without external gain-setting resistors.

Thermal resistance R_th(j-a) is 500 K/W (standard footprint) or 362 K/W (enhanced 1 cm² collector pad), directly impacting safe operating area under pulsed loads. Transient thermal impedance curves confirm reliable operation for tp ≤ 300 μs pulses with duty cycle δ ≤ 0.02, supporting PWM-driven load switching.

Key Specifications

Pinout & Package

SOT23 (TO-236AB) surface-mount plastic package with 3 leads, 1.3 mm pitch, and 2.9 mm × 1.3 mm footprint. Designed for reflow and wave soldering per IPC-7351B standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose transistor applications.

Compared with BC817-40/SNR, BC817-40,115 offers identical performance with logistics optimization, while MMBT4401LT1G trades 30% lower h_FE and 50 mV higher V_CE(sat) for broader distributor availability - making the SNR variant optimal for gain-critical, thermally constrained, or high-volume OEM builds.

Availability

BC817-40/SNR is available at Aetrix Electronics and suitable for relay driver stages, microcontroller I/O buffering, and DC-DC converter bias circuits requiring stable component supply, consistent h_FE binning, and SOT23 footprint compatibility.

Supply support for BC817-40/SNR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Nexperia is a global semiconductor expert headquartered in Nijmegen, Netherlands, specializing in high-volume, high-reliability discrete and logic devices for industrial, automotive, and consumer markets.

The BC817 series belongs to Nexperia's general-purpose transistor product line, engineered for cost-effective, robust switching and amplification in space-constrained SMT applications where predictable gain, low saturation voltage, and thermal resilience are essential.

FAQ

What is the maximum allowable base current for continuous operation?

The absolute maximum peak base current is 200 mA for single pulses ≤1 ms, but continuous operation must limit I_B to ensure junction temperature stays below 150 °C. At I_C = 500 mA and h_FE = 250, nominal I_B = 2 mA; design practice caps continuous I_B at 10 mA with appropriate series resistor to prevent thermal runaway under worst-case h_FE and ambient conditions.

Can BC817-40/SNR be used in linear amplifier configurations?

Yes - its f_T = 100 MHz, low C_c = 3 pF, and h_FE stability across I_C support Class-A and emitter-follower amplifier use up to 100 kHz. However, thermal derating must be applied: at 25 °C ambient, maximum continuous power dissipation is 250 mW, limiting usable output swing in high-gain stages without heatsinking.

How does the h_FE variation affect circuit performance at elevated temperature?

h_FE increases ~0.5%/°C above 25 °C, reaching ~1.3× nominal value at 125 °C junction temperature. This can cause unintended current rise in fixed-bias circuits; designs using emitter degeneration resistors or feedback maintain stability, while base-current-limited switches remain robust due to inherent negative feedback from V_BE decrease (~2 mV/K).

Is BC817-40/SNR qualified for automotive applications?

No - per Nexperia's revision history (Rev. 8, July 2022), the BC817_SER series is explicitly marked "non-automotive qualified" and lacks AEC-Q101 stress testing. It is intended for industrial, consumer, and computing applications only. For automotive use, Nexperia recommends the BC817-Q series variants with full qualification documentation and extended temperature screening.