onsemi BC638ZL1G

Overview

BC638ZL1G from ON Semiconductor is a PNP silicon bipolar junction transistor rated for −60 V V_CEO, −500 mA continuous collector current, and 1.5 W power dissipation at T_C = 25°C; it features h_FE ≥ 25 at I_C = −5 mA and V_CE = −2 V, V_CE(sat) ≤ −0.5 V at I_C = −500 mA/I_B = −50 mA, and f_T = 150 MHz - used in linear amplification and switching circuits in industrial power supplies and relay drivers.

For engineers reviewing the BC638ZL1G datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, TO-92 package mechanical compatibility, guaranteed h_FE min at low/mid current, thermal resistance R_JC = 83.3°C/W, and Pb-free compliance per ON Semiconductor's Soldering and Mounting Techniques Reference Manual.

Technical Context

This device operates as a medium-power PNP BJT with fixed gain structure optimized for DC amplification and saturated switching. Its safe operating area (SOA) supports pulsed currents up to −1 A at V_CE = −10 V, and its f_T of 150 MHz enables stable operation in audio-frequency amplifiers and low-speed digital interfaces.

Thermal design relies on case-mounted heat sinking due to R_JC = 83.3°C/W and R_JA = 200°C/W; V_BE(on) = −1.0 V at I_C = −500 mA confirms base drive requirements for saturation, while C_ib = 110 pF and C_ob = 9.0 pF define high-frequency input/output loading behavior.

Key Specifications

Pinout & Package

BC638ZL1G is housed in a TO-92 plastic package (Case 29, Style 14), with standardized lead configuration and Pb-free finish compliant with J-STD-020 reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC638ZL1G, BC636ZL1G trades voltage headroom for higher DC gain at moderate current, while MPSA92G provides extreme voltage tolerance at the cost of bandwidth and saturation efficiency - both require layout review for thermal and parasitic impedance differences.

Availability

BC638ZL1G is available at Aetrix Electronics and suitable for industrial relay drivers, linear audio amplifiers, DC motor speed control, and power supply error amplifiers requiring stable component supply with Pb-free compliance and TO-92 mechanical interchangeability.

Supply support for BC638ZL1G 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 (now part of onsemi) is a global semiconductor supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC638ZL1G belongs to ON Semiconductor's legacy high-current PNP transistor family designed for robust, cost-effective switching and amplification in industrial control, power management, and analog signal conditioning applications.

FAQ

What is the maximum continuous collector current rating for BC638ZL1G?

The BC638ZL1G has a maximum continuous collector current rating of −0.5 A (500 mA) at T_A = 25°C. This value assumes proper PCB copper pour or heatsinking to maintain junction temperature within −55°C to +150°C limits. Derating applies above 25°C ambient, with PD decreasing by 5 mW/°C when referenced to ambient and 12 mW/°C when referenced to case temperature. The BC638ZL1G must not exceed this current in sustained DC operation without thermal mitigation.

Is BC638ZL1G pin-compatible with BC638G?

Yes, BC638ZL1G is pin-compatible with BC638G - both use identical TO-92 (Case 29, Style 14) packaging with emitter-base-collector pinout (1-2-3). The difference lies in packaging format: BC638ZL1G ships in 2000-unit ammo boxes with Pb-free finish, while BC638G ships in 5000-unit boxes. No PCB layout change is needed when substituting BC638ZL1G for BC638G, provided handling and reflow profiles comply with Pb-free specifications.

What is the typical current-gain bandwidth product (f_T) of BC638ZL1G?

The BC638ZL1G has a typical current-gain bandwidth product (f_T) of 150 MHz, measured at I_C = −50 mA, V_CE = −2.0 V, and f = 100 MHz. This parameter defines the frequency at which small-signal current gain drops to unity and confirms suitability for audio-frequency amplification and low-speed switching applications. The BC638ZL1G maintains usable gain up to ~10 MHz in practical common-emitter configurations with appropriate biasing and decoupling.

Does BC638ZL1G meet RoHS requirements?

Yes, BC638ZL1G meets RoHS Directive 2011/65/EU requirements as a Pb-free device. Its TO-92 package uses lead-free terminations and complies with ON Semiconductor's Pb-free manufacturing standards. The "G" suffix explicitly denotes Pb-free construction, and the device supports standard reflow profiles per J-STD-020. BC638ZL1G is suitable for environmentally regulated industrial and commercial applications requiring full RoHS compliance.

What is the guaranteed minimum h_FE for BC638ZL1G at low current?

The BC638ZL1G guarantees a minimum DC current gain (h_FE) of 25 at I_C = −5.0 mA and V_CE = −2.0 Vdc. This specification ensures predictable base drive requirements in linear and switching applications operating at light-to-moderate loads. At higher currents (e.g., I_C = −150 mA), h_FE may increase to 100, but design margins should be based on the guaranteed 25 minimum at the −5 mA test condition for worst-case analysis.