onsemi BD179G

Overview

BD179G from onsemi is a plastic medium-power silicon NPN transistor designed for 5.0–10 W audio amplifiers and driver stages in complementary or quasi-complementary circuits. It delivers V_CEO = 80 V, I_C = 3.0 A, P_D = 30 W at T_C = 25°C, h_FE = 63–160 (at I_C = 0.15 A), and f_T = 3.0 MHz - enabling robust linear amplification in mid-power analog signal paths.

For engineers reviewing the BD179G datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-225 package thermal resistance (R_θJC = 4.16°C/W), safe operating area under pulse conditions, V_CE(sat) ≤ 0.8 V at I_C/I_B = 10, and Pb-free RoHS compliance for industrial audio and power stage designs.

Technical Context

The BD179G operates as a linear NPN power transistor with specified DC current gain across collector current (h_FE = 63 min at I_C = 0.15 A; 15 min at I_C = 1.0 A) and defined saturation behavior (V_CE(sat) ≤ 0.8 V, V_BE(on) ≤ 1.3 V). Its SOA curve explicitly defines secondary breakdown limits for pulse duty cycles <10% and thermal derating above 25°C.

It is electrically complementary to the BD180 PNP transistor and shares identical TO-225 (Case 77, Style 1) mechanical construction - emitter-base-collector pinout (1-3-2), backside collector tab, and 4.16°C/W junction-to-case thermal resistance - enabling matched pair use in push-pull output stages.

Key Specifications

Pinout & Package

BD179G uses the TO-225 package (Case 77, Style 1), featuring a metal backside collector tab for direct heatsink mounting and three leads in a straight-line configuration. The package provides mechanical robustness and thermal performance suitable for medium-power discrete amplifier applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJE179G and BD139, BD179G uniquely balances 80 V voltage rating, 30 W dissipation, TO-225 thermal interface, and complementary pairing with BD180 - making it the optimal choice for thermally demanding, rail-voltage-critical audio output stages requiring matched bipolar pairs.

Availability

BD179G is available at Aetrix Electronics and suitable for audio power amplifiers, quasi-complementary drivers, and industrial signal generators requiring stable component supply and long-term manufacturability.

Supply support for BD179G 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, with leadership in power management, analog, sensors, and discrete devices.

The BD179G belongs to onsemi's legacy medium-power bipolar transistor product line, engineered specifically for linear audio amplification, driver stages, and complementary output circuits in industrial and consumer audio systems.

FAQ

What is the maximum collector-emitter voltage rating for BD179G?

The BD179G has a maximum collector-emitter sustaining voltage V(BR)_CEO of 80 Vdc at I_C = 0.1 Adc and I_B = 0. This rating defines the absolute upper limit for DC voltage applied between collector and emitter before breakdown occurs. Exceeding this value risks permanent device failure, especially under sustained or pulsed conditions outside the published SOA boundaries. Designers must ensure all operating points for BD179G remain within this 80 V ceiling, including transient spikes and ripple components in power supply rails.

Is BD179G pin-compatible with BD180?

BD179G is electrically complementary to BD180 but not pin-compatible - BD180 is a PNP transistor with identical TO-225 (Case 77, Style 1) package and matching pinout (Emitter-Base-Collector = pins 1-3-2), enabling direct physical placement as a pair in push-pull layouts. However, polarity reversal means external circuit connections must be mirrored: BD179G's emitter connects to ground/negative rail while BD180's emitter connects to positive rail. Both share identical thermal and mechanical interfaces, simplifying heatsink integration in complementary amplifier designs.

What is the thermal resistance from junction to case for BD179G?

The BD179G has a maximum junction-to-case thermal resistance R_θJC of 4.16°C/W, measured under standard test conditions. This value reflects the thermal path from the silicon die to the metal backside collector tab, which serves as the primary heatsink interface. In practice, effective thermal performance depends on mounting pressure, thermal interface material quality, and heatsink surface flatness. Designers must apply derating per the datasheet's 240 mW/°C slope above 25°C case temperature to avoid exceeding the 150°C maximum junction temperature.

Does BD179G support audio-frequency amplification up to 20 kHz?

Yes, BD179G supports full-audio-band amplification up to 20 kHz due to its 3.0 MHz current-gain bandwidth product (f_T) measured at I_C = 250 mAdc, V_CE = 10 Vdc, and f = 1.0 MHz. At typical audio operating currents (0.1–1.0 A), the device maintains sufficient gain margin and phase stability across the 20 Hz–20 kHz range. Its SOA curves and low V_CE(sat) further ensure linear operation without slew-induced distortion when driving reactive speaker loads.

What does the "G" suffix in BD179G signify?

The "G" suffix in BD179G indicates a Pb-free (lead-free) package compliant with RoHS Directive 2011/65/EU. This designation confirms that all solderable terminations and internal construction meet strict heavy-metal restrictions, including ≤1000 ppm lead content. The "G" marking appears on the device body alongside year-week date code (YWW) and is verified in onsemi's official packaging documentation. BD179G is not a different electrical variant - its electrical specifications, thermal performance, and mechanical dimensions are identical to non-G versions, except for the environmentally compliant finish.