onsemi 2SB1228

Overview

2SB1228 from SANYO Semiconductor is a PNP epitaxial planar silicon Darlington transistor designed for high-current switching in industrial driver circuits. It delivers V_CEO = −100 V, I_C = −8 A continuous, V_CE(sat) = −1.5 V at −4 A/−8 mA, h_FE = 1500–4000, and f_T = 20 MHz - enabling robust motor, relay, and printer hammer control.

For engineers reviewing the 2SB1228 datasheet, pinout, applications, or equivalent options, key selection considerations include its micaless TO-220ML package, wide Active Safe Operating Area (ASO), low saturation voltage under high current, and suitability for constant-voltage regulator output stages.

Technical Context

The 2SB1228 integrates two cascaded PNP transistors in a single die to achieve high DC current gain while maintaining thermal stability at elevated junction temperatures up to 150°C. Its Darlington configuration enables base drive current reduction by ~500× compared to single transistors at equivalent collector currents.

Designed for linear and switching operation, it supports pulse currents up to −12 A with t_on = 0.6 µs and t_f = 1.6 µs, and exhibits stable h_FE across −40°C to +120°C ambient range - critical for industrial motor drivers requiring consistent turn-on behavior under thermal stress.

Key Specifications

Pinout & Package

2SB1228 uses the micaless TO-220ML package (SANYO designation), featuring a metal tab electrically connected to the collector for direct heatsink mounting without insulating washers.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP Darlington transistor applications.

Compared with 2SB1228, both alternatives offer reduced voltage headroom, lower continuous current, and narrower SOA - making them unsuitable for demanding motor or printer hammer applications where −100 V rating and −8 A capability are required for reliability and longevity.

Availability

2SB1228 is available at Aetrix Electronics and suitable for motor drivers, relay drivers, printer hammer drivers, and constant-voltage regulators requiring stable component supply and long-term industrial availability.

Supply support for 2SB1228 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

SANYO Semiconductor was a Japanese semiconductor manufacturer specializing in power discrete devices, analog ICs, and optoelectronics before its acquisition by ON Semiconductor in 2013.

The 2SB1228 belongs to SANYO's high-power Darlington transistor family engineered for industrial actuator control - emphasizing ruggedness, wide SOA, and simplified base drive in harsh thermal environments.

FAQ

What is the maximum continuous collector current for the 2SB1228?

The 2SB1228 supports a maximum continuous collector current of −8 A at case temperature T_c = 25°C with adequate heatsinking. At ambient temperature T_a = 25°C without heatsink, the rating drops to 2.0 W dissipation, limiting usable current to approximately −2.5 A depending on layout and airflow. Derating curves in the datasheet (No.2214-4/4) must be applied for operation above 25°C.

Does the 2SB1228 require a mica insulator when mounted to a heatsink?

No - the 2SB1228 uses a micaless TO-220ML package where the metal tab is internally connected to the collector terminal and designed for direct metal-to-metal contact with the heatsink. This eliminates the need for insulating washers or sil-pads, improving thermal resistance by ~0.5°C/W compared to insulated mounting methods.

What is the typical DC current gain (h_FE) of the 2SB1228 at −4 A collector current?

The 2SB1228 exhibits a typical DC current gain (h_FE) of 4000 at V_CE = −3 V and I_C = −4 A, with a guaranteed minimum of 1500 under the same conditions. This high gain enables direct drive from microcontroller GPIO pins or logic buffers without additional pre-driver stages.

Can the 2SB1228 be used in parallel with another 2SB1228 for higher current handling?

Parallel operation of multiple 2SB1228 devices is not recommended without individual emitter resistors due to gain and V_BE(sat) mismatches across units. The datasheet does not specify matching tolerances, and thermal coupling differences can cause current imbalance - potentially leading to thermal runaway in one device. For >8 A applications, consider a single higher-rated device or a dedicated power module.

What is the Safe Operating Area (SOA) limit for the 2SB1228 at 100 µs pulse width?

At 100 µs pulse width, the 2SB1228 SOA (per Fig. ITR09358/ITR09359) supports up to −60 V V_CE at −6 A, or −100 V at −2 A. These limits assume T_j ≤ 150°C and proper heatsinking; exceeding them risks second breakdown. Pulse testing must follow the specified test circuit in the datasheet to ensure validity.