onsemi 2SD1684T

Overview

2SD1684T from SANYO is a PNP epitaxial planar silicon transistor designed for high-voltage switching applications, with V_CEO = −100 V, I_C = −1.5 A, P_C = 1.5 W at T_C = 25 °C, and low saturation voltage V_CE(sat) = −0.3 V at I_C = −500 mA / I_B = −50 mA. It is used in DC-DC converter power switches and relay drivers requiring robust breakdown margin and thermal stability.

For engineers reviewing the 2SD1684T datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed h_FE classification (Group T: h_FE = 200–400), TO-126ML package thermal performance, V_CB0 = −120 V rating, and verified switching times (t_on = 80 ns, t_off = 1000 ns) under defined test conditions.

Technical Context

This device operates as a medium-power PNP bipolar junction transistor optimized for linear and switching operation in industrial power control circuits. Its FBET/MBIT process enables high breakdown voltage and low V_CE(sat), while the plastic-covered heat sink structure supports high-density PCB mounting without auxiliary heatsinking at rated power.

Electrical behavior is characterized at T_a = 25 °C with strict derating above T_j = 150 °C. Switching performance is validated using standardized test circuits with specified base drive resistance and load conditions - not extrapolated or simulated.

Key Specifications

Pinout & Package

2SD1684T is housed in the TO-126ML package - a molded plastic variant of TO-126 with integrated heat sink tab, enabling direct PCB thermal coupling. Pin assignment is fixed: Pin 1 = Emitter, Pin 2 = Collector (tab-connected), Pin 3 = Base.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2SB1144 and MJD2955T4, the 2SD1684T uniquely balances 100 V breakdown, 1.5 A current, and 200–400 h_FE in a compact TO-126ML package - making it optimal for space-constrained, medium-voltage industrial switching where precise gain control and thermal efficiency are both critical.

Availability

2SD1684T is available at Aetrix Electronics and suitable for DC-DC converters, relay drivers, motor brake circuits, and industrial lamp dimmers requiring stable component supply and long-term obsolescence management.

Supply support for 2SD1684T 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 Electric Co., Ltd. was a Japanese semiconductor manufacturer known for high-reliability discrete devices and analog ICs before its acquisition by Panasonic in 2012.

The 2SD1684T belongs to SANYO's legacy PNP/NPN switching transistor family engineered for industrial power control - emphasizing ruggedness, thermal stability, and guaranteed parametric bins for predictable system-level performance.

FAQ

What is the maximum junction temperature for the 2SD1684T?

The 2SD1684T has a maximum junction temperature (T_j) of +150 °C, as specified in its Absolute Maximum Ratings table. Operation beyond this limit risks permanent degradation of the silicon die and bond wires. Thermal design must ensure that power dissipation - including both DC conduction and switching losses - keeps T_j within this bound under worst-case ambient and airflow conditions. The 2SD1684T's TO-126ML package relies on PCB copper area for heat spreading, so layout must allocate sufficient thermal pad area connected to internal ground or power planes.

Is the 2SD1684T pin-compatible with the 2SB1144?

Yes, the 2SD1684T and 2SB1144 share identical pinout (Emitter–Collector–Base), package (TO-126ML), and absolute maximum ratings. They differ only in h_FE binning: 2SD1684T is Group T (200–400), while 2SB1144 is Group Q (120–240). Therefore, the 2SD1684T can replace the 2SB1144 in most circuits, but designers should verify base drive sufficiency - especially in low-current or high-temperature conditions where lower-gain variants may not saturate fully.

Does the 2SD1684T support switching at frequencies above 100 kHz?

No - the 2SD1684T is not recommended for switching above ~100 kHz. Its measured t_off = 1000 ns and f_T = 120 MHz reflect small-signal gain bandwidth, not usable switching speed. At high frequencies, stored charge and minority-carrier lifetime cause excessive switching losses and thermal runaway. For >100 kHz operation, MOSFETs or RF-optimized BJTs with faster storage time specs should be selected instead of the 2SD1684T.

What does the "T" suffix in 2SD1684T indicate?

The "T" suffix in 2SD1684T denotes the h_FE gain bin: Group T specifies DC current gain (h_FE) between 200 and 400 at V_CE = −5 V and I_C = −100 mA. This binning enables consistent base drive design across production lots and ensures predictable saturation behavior in switching applications. Other variants include 2SD1684Q (h_FE = 120–240) and 2SD1684S (h_FE = 180–360); the 2SD1684T is the highest-gain standard offering in this family.

Can the 2SD1684T be used in linear amplifier configurations?

While the 2SD1684T is characterized for switching, it can operate in Class-A or Class-AB linear amplifiers - provided biasing stays within its Safe Operating Area (SOA) limits and thermal management prevents T_j > 150 °C. However, its h_FE variation across temperature and current, plus lack of published linearity metrics (e.g., THD, f_T flatness), makes it less suitable than purpose-designed audio transistors. For linear use, verify stability with appropriate emitter degeneration and avoid operation near V_CEO or P_C limits. The 2SD1684T remains best suited for saturated-switch applications.