Nexperia USA Inc. BF821-QR

Overview

BF821-QR from Nexperia is a PNP high-voltage bipolar junction transistor in SOT23 package, rated for −300 V V_CEO, −50 mA I_C, and 250 mW P_tot, with DC current gain (h_FE) ≥50 at −25 mA and −20 V. It serves as a high-voltage switching or amplification element in telephony line interface circuits and automotive signal conditioning stages.

For engineers reviewing the BF821-QR datasheet, BF821-QR pinout, BF821-QR application, or BF821-QR equivalent, key selection criteria include verified −300 V collector-emitter blocking capability, AEC-Q101 qualification for automotive use, thermal resistance of 500 K/W under standard PCB mounting, and compatibility with SOT23 reflow footprints per IPC-7351.

Technical Context

This discrete PNP transistor operates in linear or saturated switching mode with V_CEsat ≤ −800 mV at −30 mA/−5 mA drive, and exhibits f_T = 60 MHz at −10 V/−10 mA. Its low leakage-ICBO ≤ −10 nA at −200 V and 25 °C-supports stable high-impedance bias networks.

Designed for high-voltage analog and digital signal routing, it features an emitter-base breakdown voltage (V_EBO) of −5 V and peak base current rating of −50 mA, enabling robust gate/base drive in relay drivers and telecom line protection circuits.

Key Specifications

Pinout & Package

SOT23 plastic surface-mount package (2.9 mm × 1.3 mm × 1.0 mm body, 1.9 mm pin pitch), with gull-wing leads and collector-connected tab for thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP high-voltage switching applications.

Compared with BF821-QR, NSS12201LT1G trades voltage headroom for higher DC gain and tighter h_FE distribution, while DXT75100Q-13 extends both voltage and current capability at the cost of thermal performance on standard PCB layouts.

Availability

BF821-QR is available at Aetrix Electronics and suitable for telecom infrastructure, automotive sensor modules, industrial relay drivers, and medical power sequencing requiring stable component supply and AEC-Q101 traceability.

Supply support for BF821-QR 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 focused on high-volume, high-reliability discrete and logic devices, with leadership in automotive-qualified components and advanced packaging.

BF821-QR belongs to Nexperia's high-voltage bipolar transistor product line, engineered specifically for robust signal switching and conditioning in harsh-voltage environments such as telecom line interfaces and automotive subsystems.

FAQ

Is BF821-QR pin-compatible with its NPN complements BF820-Q and BF822-Q?

Yes-BF821-QR shares identical SOT23 pinout (1=Base, 2=Emitter, 3=Collector) with BF820-Q and BF822-Q, enabling direct layout reuse in complementary pair designs. However, polarity reversal requires schematic-level inversion of biasing and load connections to maintain functional equivalence.

What is the maximum allowable PCB copper area for thermal performance at full 250 mW dissipation?

Per datasheet Section 8, full-rated 250 mW dissipation requires a 1 cm² single-sided copper pad on the collector pad, tin-plated and connected directly to the SOT23 collector terminal (Pin 3). Reducing pad area increases R_th(j-a) beyond 500 K/W and risks junction temperature exceeding 150 °C.

Does BF821-QR support wave soldering, and what footprint is recommended?

Yes-Nexperia provides dedicated wave soldering footprint (Fig. 3) with 1.4 mm × 2.2 mm solder lands and 2.8 mm × 4.5 mm occupied area. Use sot023_fw pattern with preferred transport direction aligned to pin 1–3 axis to ensure uniform wetting and avoid tombstoning.

How does ICBO drift with temperature, and is it specified at elevated junction temperatures?

ICBO rises to ≤ −10 µA at T_j = 150 °C (Table 7), representing a 1000× increase over the 25 °C value (≤ −10 nA). This exponential drift must be accounted for in high-temperature bias networks where leakage could shift operating points by >10%.