onsemi 2SB1123T-TD-E

Overview

2SB1123T-TD-E from onsemi is a PNP bipolar junction transistor (BJT) designed for general-purpose switching and amplification in low-voltage, medium-current applications. It features a DC current gain (h_FE) of 120–270 at I_C = 2 mA, V_CE = 2 V; maximum collector-emitter voltage V_CEO = 50 V; continuous collector current I_C = 100 mA; and power dissipation P_D = 200 mW in the SOT-23 package. It is commonly used in signal conditioning stages of consumer audio interfaces and LED driver bias networks.

For engineers reviewing the 2SB1123T-TD-E datasheet, pinout, applications, or equivalent options, key selection criteria include verified h_FE range at low I_C, guaranteed V_CEO margin for 3.3 V/5 V rail operation, thermal derating behavior in SOT-23, and complementary pairing with NPN counterparts like 2SD1781T-TD-E for push-pull configurations.

Technical Context

The 2SB1123T-TD-E operates as a standard silicon PNP BJT with epitaxial base construction, optimized for linear amplification and saturated switching in discrete analog front-ends. Its h_FE is specified across I_C = 0.1–100 mA and V_CE = 2 V, supporting stable biasing in Class-A amplifier stages and active-low switch drivers.

It exhibits a typical V_CE(sat) of 0.3 V at I_C = 50 mA and I_B = 5 mA, enabling efficient low-side switching in battery-powered sensor nodes. The device meets JEDEC JESD47 reliability standards and is rated for operation from −55 °C to +150 °C junction temperature.

Key Specifications

Pinout & Package

2SB1123T-TD-E is housed in a surface-mount SOT-23 (TO-236AB) plastic package with gull-wing leads, measuring 2.9 mm × 1.3 mm × 1.0 mm. Thermal resistance R_θJA is 357 °C/W (JEDEC Low Effective Thermal Resistance Mounting).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP BJT switching and amplification applications.

Compared with 2SB1123T-TD-E, 2SB1210T-TD-E trades gain precision for higher voltage capability, while MMBT4403 offers broader h_FE spread and slightly reduced efficiency but greater supply-chain flexibility in high-volume production.

Availability

2SB1123T-TD-E is available at Aetrix Electronics and suitable for audio signal conditioning, LED bias control, logic-level translation, and power sequencing applications requiring stable component supply and traceable sourcing.

Supply support for 2SB1123T-TD-E 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 is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The 2SB1123T-TD-E belongs to onsemi's General Purpose Transistor product line, engineered for reliable discrete amplification and switching in space-constrained, low-power electronic systems.

FAQ

What is the maximum operating temperature for the 2SB1123T-TD-E?

The 2SB1123T-TD-E has a specified junction temperature range of −55 °C to +150 °C. Its absolute maximum rating for continuous operation is defined by thermal derating: at ambient temperatures above 25 °C, power dissipation must be reduced linearly per the R_θJA = 357 °C/W specification. Full 200 mW operation is only guaranteed at T_A = 25 °C; at 85 °C ambient, max P_D drops to ~115 mW. This makes the 2SB1123T-TD-E suitable for sealed industrial enclosures but not high-temperature under-hood automotive locations without heatsinking.

Is the 2SB1123T-TD-E pin-compatible with the 2SB1210T-TD-E?

Yes, the 2SB1123T-TD-E and 2SB1210T-TD-E share identical SOT-23 pinout (Emitter-Base-Collector on pins 1–2–3) and mechanical footprint. However, they are not functionally interchangeable without circuit review: the 2SB1210T-TD-E has higher V_CEO (80 V vs. 50 V) but lower h_FE (60–120 vs. 120–270), resulting in different bias stability and saturation characteristics. Substitution may require recalculating base resistors and verifying V_CE(sat) margins in the target application.

Does the 2SB1123T-TD-E support pulsed operation beyond its DC current rating?

Yes, the 2SB1123T-TD-E supports short-duration pulsed collector currents up to 200 mA, provided pulse width ≤ 100 µs and duty cycle ≤ 1%. This capability is documented in the Safe Operating Area (SOA) curve of the official onsemi datasheet. For example, it can drive brief LED strobes or relay coil inrush currents without exceeding thermal limits-provided average power remains within the 200 mW DC limit and PCB layout provides adequate transient heat dissipation.

What is the typical V_BE of the 2SB1123T-TD-E at I_C = 2 mA?

The typical base-emitter forward voltage (V_BE) of the 2SB1123T-TD-E is 0.75 V at I_C = 2 mA and V_CE = 2 V, with a guaranteed range of 0.65 V to 0.85 V across temperature and process variation. This value is critical for designing accurate base bias networks and calculating required base drive current (I_B ≈ I_C/h_FE). The 2SB1123T-TD-E's tight V_BE distribution supports repeatable performance in production assemblies without calibration.

Can the 2SB1123T-TD-E be used in complementary symmetry amplifier stages?

Yes, the 2SB1123T-TD-E is explicitly designed for complementary use with its matched NPN counterpart, the 2SD1781T-TD-E. Both devices share identical SOT-23 packaging, closely aligned h_FE ranges (2SD1781T-TD-E: 120–270), and symmetrical V_CE(sat) and f_T characteristics. This pairing enables balanced Class-AB audio output stages and rail-to-rail op-amp output buffers where thermal tracking and gain matching reduce crossover distortion in the 2SB1123T-TD-E–based half of the circuit.