onsemi BDX34C

Overview

BDX34C from ON Semiconductor is a PNP epitaxial silicon power Darlington transistor in TO-220 package, rated for -100 V V_CEO, -10 A continuous collector current, 70 W power dissipation at T_C=25°C, and minimum DC current gain (h_FE) of 750 at I_C = -3 A. It serves as a high-gain switching or linear amplification device in industrial motor control and power supply output stages.

For engineers reviewing the BDX34C datasheet, pinout, applications, or equivalent options, key selection criteria include its -100 V blocking capability, -2.5 V V_CE(sat) at I_C = -3 A / I_B = -6 mA, complementary pairing with BDX33C, and TO-220 thermal performance under sustained conduction.

Technical Context

The BDX34C operates as a monolithic PNP Darlington pair with integrated base-emitter shunt resistor not present-external base drive is required. Its safe operating area (SOA) supports both continuous linear operation and pulsed switching up to -15 A with 1.5% duty cycle, constrained by junction temperature limits of 150°C and thermal resistance R_θJC ≈ 1.8 °C/W (derived from 70 W @ ΔT=125°C).

It exhibits low saturation voltage (-2.5 V) and high current gain (≥750), enabling efficient base-driven switching in high-side configurations. The device's V_CEO(sus) = -100 V and V_CBO = -100 V confirm symmetrical breakdown ratings suitable for inductive load commutation without snubber dependency in moderate-speed applications.

Key Specifications

Pinout & Package

BDX34C uses the standard TO-220 package with 3 leads: Base (pin 1), Collector (pin 2), Emitter (pin 3). The metal tab is electrically connected to the collector and must be isolated from chassis ground unless circuit topology requires collector-to-heatsink connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD32C and BDX54C, the BDX34C offers optimal balance of through-hole manufacturability, thermal capability, and gain for mid-power industrial controls-neither over-specified nor thermally marginal in standard chassis-mounted implementations.

Availability

BDX34C is available at Aetrix Electronics and suitable for industrial motor control, linear power regulation, and relay driving applications requiring stable component supply across multi-year production cycles.

Supply support for BDX34C 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

ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud power applications.

The BDX34C belongs to ON Semiconductor's legacy power bipolar transistor family, designed specifically for robust, cost-effective high-current linear and switching tasks in industrial equipment where reliability under thermal stress is critical.

FAQ

What is the maximum continuous collector current rating for BDX34C?

The BDX34C has a maximum continuous collector current (I_C) rating of -10 A at case temperature T_C = 25°C. This rating decreases with rising case temperature per the power derating curve in the datasheet, reaching zero at T_C ≈ 115°C. For reliable long-term operation, design must ensure thermal management keeps T_C within limits-typically using a heatsink with R_θCA ≤ 2.5 °C/W for 5 A continuous loads. The BDX34C must never exceed this current under DC conditions without thermal derating.

Does BDX34C include an integrated base-emitter resistor?

No, the BDX34C does not include an integrated base-emitter resistor. It is a standard PNP Darlington transistor requiring external base current control. Unlike digital transistors (e.g., MMBT2907A with built-in resistors), the BDX34C demands discrete base drive circuitry-such as a current-limiting resistor or dedicated driver IC-to set appropriate I_B for desired I_C. This gives designers full flexibility in gain and switching speed trade-offs but requires careful calculation of base drive requirements per the h_FE and V_BE(on) specifications in the BDX34C datasheet.

Can BDX34C be used as a direct replacement for BDX34B in existing designs?

Yes, the BDX34C can replace BDX34B in most cases because both share identical pinout, package (TO-220), and electrical characteristics except for higher voltage ratings: BDX34C supports -100 V V_CEO versus -80 V for BDX34B. No PCB changes are needed, but designers should verify that the increased voltage margin does not introduce unintended timing or stability effects-especially in linear amplifier configurations where higher V_CEO may correlate with slightly different capacitance profiles. The BDX34C remains fully compatible as a functional upgrade in all BDX34B applications.

What is the safe operating area (SOA) limitation for BDX34C at 100 µs pulse width?

At 100 µs pulse width, the BDX34C SOA allows up to approximately -12 A collector current at -50 V V_CE, based on the published SOA graph (Figure 5) in the datasheet. This assumes single-pulse operation with negligible thermal buildup. The limit is defined by second breakdown constraints-not just power dissipation-so exceeding these boundaries risks localized junction failure even with short durations. For repetitive pulses, average power and thermal cycling must also be evaluated. Always reference the actual BDX34C SOA plot and apply derating for temperature and duty cycle when designing with the BDX34C.

Is BDX34C RoHS compliant and halogen-free?

Yes, the BDX34C manufactured by ON Semiconductor is RoHS compliant and halogen-free per ON Semiconductor's product compliance documentation. The device meets EU Directive 2011/65/EU (RoHS 2) and IEC 61249-2-21:2011 for bromine and chlorine content (<900 ppm) and antimony (<900 ppm). Material declarations and certificates of compliance are available via ON Semiconductor's website or authorized distributors. When sourcing BDX34C for regulated markets, always confirm the date code and packaging type match the latest qualified environmental specification revision.