onsemi NST847BF3T5G

Overview

NST847BF3T5G from onsemi is an NPN general-purpose bipolar junction transistor in SOT-1123 package, rated for 45 V_CEO, 100 mA continuous collector current, and DC current gain (h_FE) of 200–450 at I_C = 10 mA. It delivers low saturation voltage (V_CE(sat) ≤ 0.25 V at I_C = 10 mA/I_B = 0.5 mA) and supports compact low-power amplifier and switching applications in space-constrained PCBs.

For engineers reviewing the NST847BF3T5G datasheet, pinout, applications, or equivalent options, key selection criteria include its SOT-1123 footprint, guaranteed h_FE range, thermal resistance (R_JA = 360 °C/W on 500 mm² copper), V_CE(sat) performance at low drive, and Pb-free compliance for modern assembly processes.

Technical Context

This device operates as a discrete NPN BJT optimized for linear amplification and low-current switching. Its design emphasizes board-space efficiency via the ultra-small SOT-1123 (0.80 × 0.60 × 0.37 mm) package and leverages high h_FE consistency across temperature to reduce base drive requirements in bias-sensitive circuits.

Electrical behavior is characterized by tight V_CE(sat) control (≤0.25 V at I_C/I_B = 10), low input/output capacitance (C_ibo = 10 pF, C_obo = 4.5 pF), and f_T = 100 MHz - enabling stable operation in audio preamps, sensor interface stages, and LED driver switches up to several hundred kHz.

Key Specifications

Pinout & Package

The NST847BF3T5G is housed in the SOT-1123 surface-mount package (Case 524AA, 0.80 × 0.60 × 0.37 mm, 0.35 mm pitch), optimized for ultra-dense layouts. Pin configuration follows Style 1: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT847LT1G and BC847B,215, the NST847BF3T5G provides superior board-area efficiency and lower V_CE(sat) at typical bias points, making it preferred for miniaturized, low-loss designs where thermal management relies on compact copper layout rather than large heatsinks.

Availability

NST847BF3T5G is available at Aetrix Electronics and suitable for portable audio systems, wearable sensor nodes, LED status indicators, and low-voltage logic interface circuits requiring stable component supply and RoHS-compliant sourcing.

Supply support for NST847BF3T5G 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.

The NST847BF3T5G belongs to onsemi's general-purpose bipolar transistor family, engineered specifically for space-constrained, low-power analog and switching functions in consumer and industrial edge devices.

FAQ

What is the maximum collector-emitter voltage rating for the NST847BF3T5G?

The NST847BF3T5G has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc, verified per the onsemi datasheet under test condition I_C = 10 mA. This rating defines the absolute upper limit for voltage applied between collector and emitter with the base open. Exceeding this value risks avalanche breakdown and permanent device damage. The NST847BF3T5G must be operated within this limit in all circuit configurations, including transient conditions.

Does the NST847BF3T5G support Pb-free reflow soldering processes?

Yes, the NST847BF3T5G is explicitly marked as a Pb-free device in the onsemi datasheet and qualified for standard lead-free reflow profiles (e.g., JEDEC J-STD-020). Its SOT-1123 package uses matte tin plating compatible with peak temperatures up to 260 °C. The "G" suffix in NST847BF3T5G confirms RoHS compliance, and no lead-based finishes or internal solder systems are used - ensuring full compatibility with modern electronics assembly lines.

What is the thermal resistance (R_JA) of the NST847BF3T5G under standard PCB conditions?

The NST847BF3T5G exhibits two specified R_JA values depending on copper area: 432 °C/W with 100 mm² of 1 oz copper (Note 1), and 360 °C/W with 500 mm² of 1 oz copper (Note 2). These values are measured per JEDEC standards and directly impact allowable power dissipation. For example, at 25 °C ambient and 500 mm² copper, the NST847BF3T5G can safely dissipate 347 mW before reaching its 150 °C junction limit - a critical parameter for thermal design validation.

How does the h_FE range of the NST847BF3T5G compare to similar SOT-1123 transistors?

The NST847BF3T5G guarantees h_FE = 200–450 at I_C = 10 mA and V_CE = 5 V, matching the high-gain bin of industry-standard NPN transistors like the BC847 series but in a smaller SOT-1123 package. Unlike generic variants with wider spreads (e.g., 110–800), this controlled range simplifies bias network design and improves batch-to-batch consistency - a key advantage confirmed in onsemi's production test data for the NST847BF3T5G.

Can the NST847BF3T5G be used in RF amplifier stages?

The NST847BF3T5G has an f_T of 100 MHz, indicating usable gain up to low-VHF frequencies, but it is not characterized or specified for RF amplifier use. Its datasheet focuses on general-purpose linear and switching applications, with no RF-specific parameters (e.g., S-parameters, noise figure above 100 kHz, or gain flatness). While functional in narrowband 27–49 MHz oscillator or buffer stages, the NST847BF3T5G should not replace purpose-built RF transistors in communication systems requiring broadband linearity or EMI control.