onsemi 2SC3784

Overview

2SC3784 from SANYO is an NPN epitaxial planar silicon transistor designed for inductive load switching in motor, relay, and printer hammer drivers. It features a 60±10 V on-chip Zener diode between collector and base, 1.2 A DC collector current rating, 1.2 W collector dissipation at Tc=25°C, and a minimum DC current gain (h_FE) of 100 at I_C=5 mA, V_CE=5 V.

For engineers reviewing the 2SC3784 datasheet, pinout, applications, or equivalent options, key selection criteria include its wide safe operating area (ASO), high inductive load handling capability, built-in Zener protection, and TO-126LP package suitability for medium-power driver stages requiring robust turn-off behavior under L-load conditions.

Technical Context

The 2SC3784 operates as a medium-power NPN switching transistor with integrated base-collector Zener clamping (60±10 V), enabling reliable commutation of inductive loads without external snubbers. Its ASO is rated up to 15 mJ under single-pulse conditions, supporting peak collector currents of 2.5 A with controlled saturation characteristics.

Electrical behavior is defined by V_CE(sat) ≤ 1.5 V at I_C = 1.2 A, I_B = 2 mA; V_BE(sat) ≤ 1.2 V under same conditions; and f_T = 180 MHz at V_CE = 5 V, I_C = 5 mA - confirming suitability for fast-switching, non-RF driver applications where gain-bandwidth trade-offs are secondary to ruggedness and thermal stability.

Key Specifications

Pinout & Package

SANYO TO-126LP package: 3-lead plastic molded case with metal tab connected to collector; intended for through-hole mounting with heatsink interface via tab.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2SC3784, the 2SC3807 offers higher voltage tolerance but reduced current gain, while BU406 delivers vastly higher power handling at the cost of complexity and missing integrated protection - making 2SC3784 optimal for cost-sensitive, medium-voltage L-load drivers needing simplicity and reliability.

Availability

2SC3784 is available at Aetrix Electronics and suitable for printer hammer drivers, relay interface modules, and small DC motor control systems requiring stable component supply and long-term industrial availability.

Supply support for 2SC3784 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 2SC3784 belongs to SANYO's general-purpose power transistor product line, engineered specifically for ruggedized inductive load switching in office automation, industrial controls, and electromechanical actuation systems.

FAQ

What is the maximum safe collector-emitter voltage for 2SC3784?

The absolute maximum V_CEO rating for 2SC3784 is 50 V at T_a = 25°C. Exceeding this voltage risks avalanche breakdown. The device includes a 60±10 V on-chip Zener diode between collector and base, which clamps flyback transients but does not raise the V_CEO rating. For reliable operation, keep steady-state V_CE below 40 V in designs using 2SC3784.

Does 2SC3784 require an external flyback diode when driving inductive loads?

No - 2SC3784 integrates a 60±10 V Zener diode between collector and base, providing intrinsic clamping of inductive kickback. This eliminates the need for an external flyback diode in most relay, solenoid, and printer hammer applications where peak reverse voltage stays within the Zener window. However, verify transient energy against the 15 mJ ASO limit in your specific 2SC3784 circuit layout.

What is the typical base current required to saturate 2SC3784 at 1.2 A collector current?

At I_C = 1.2 A, 2SC3784 achieves full saturation with I_B ≥ 2 mA, per datasheet test condition (V_CE(sat) ≤ 1.5 V). With h_FE ranging from 100 to 400, a design target of I_B = 4–6 mA provides robust margin across temperature and process variation. Always confirm V_BE(sat) ≤ 1.2 V at this drive level in your 2SC3784 application.

Can 2SC3784 be used in surface-mount designs?

No - 2SC3784 is packaged exclusively in the through-hole TO-126LP case with a metal tab for heatsinking. It has no surface-mount variant. Attempting SMT reflow will damage the device due to thermal mismatch and lack of compatible footprint. For SMT alternatives, consider evaluating modern equivalents like MMBT4401 or NSS12201LT1G, though these lack the integrated Zener and ASO performance of 2SC3784.

How does the Safe Operating Area (ASO) of 2SC3784 impact its use in pulse-driven applications?

The 2SC3784 specifies a 15 mJ single-pulse ASO at T_c = 25°C, allowing safe switching of inductive loads with energy ≤15 mJ per pulse. This directly limits permissible combinations of peak current, voltage, and pulse width - e.g., 2.5 A × 40 V × 150 ns ≈ 15 mJ. For repetitive pulses, derate based on duty cycle and thermal resistance; always validate with oscilloscope measurements on the actual 2SC3784 in-circuit.