BC373RL1G Equivalent & Substitute Parts

Part Overview

The BC373RL1G is an NPN Darlington bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features an 80 V collector-emitter breakdown voltage rating and a maximum collector current of 1 A, housed in a TO-92 through-hole package. The BC373RL1G is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing design support and procurement continuity.

Substiute Parts

BC373RL1G

onsemiIn Stock: 3378BC373RL1G Datasheet

Current PartRFQ

ZTX603STZ

Diodes IncorporatedIn Stock: 889ZTX603STZ Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BC373RL1G is determined by equivalence across the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

• Transistor topology: NPN Darlington configuration
• Maximum collector current: 1 A
• Collector-emitter breakdown voltage: 80 V
• Through-hole mounting compatibility

Mechanical Compatibility:

• Package form factor: TO-92 or TO-92-compatible package (E-Line)
• Lead configuration: Formed leads suitable for through-hole insertion

The ZTX603STZ meets these substitution criteria, maintaining identical maximum ratings for collector current and breakdown voltage while providing compatible through-hole packaging in an E-Line form factor.

Parameter Comparison

Engineering Selection Recommendations

The ZTX603STZ serves as a direct functional substitute for the BC373RL1G based on the following factors:

Electrical Compatibility: Both devices maintain identical maximum ratings for collector current (1 A) and collector-emitter breakdown voltage (80 V), ensuring safe operation within existing circuit designs without modification to current-limiting or voltage-protection components.

Package Compatibility: The ZTX603STZ E-Line package is mechanically compatible with TO-92 through-hole PCB layouts. The formed-lead configuration accommodates standard through-hole insertion and soldering processes.

Product Status and Compliance: The ZTX603STZ is classified as active, ensuring long-term availability and supply chain continuity. The device carries ROHS3 compliance certification, meeting current environmental and regulatory requirements. Both devices maintain REACH Unaffected status and identical Moisture Sensitivity Level (MSL) ratings.

Performance Considerations: The ZTX603STZ provides enhanced maximum power dissipation (1 W versus 625 mW) and an extended operating temperature range (-55°C to 200°C versus -55°C to 150°C), offering improved thermal headroom and broader environmental applicability. The transition frequency of the ZTX603STZ (150 MHz) is lower than the BC373RL1G (200 MHz); this difference is not limiting for general-purpose switching applications but should be evaluated for high-frequency signal processing circuits.

Frequently Asked Questions (FAQ)

Q: Can the ZTX603STZ directly replace the BC373RL1G in existing PCB designs?

A: Yes. Both devices are NPN Darlington transistors with identical maximum collector current (1 A) and breakdown voltage (80 V) ratings. The ZTX603STZ E-Line package is mechanically compatible with TO-92 through-hole footprints. No circuit modifications are required for standard switching applications.

Q: What are the differences in DC current gain between these devices?

A: The BC373RL1G specifies a minimum DC current gain (hFE) of 10,000 at 100 mA and 5 V. The ZTX603STZ specifies a minimum hFE of 2,000 at 1 A and 5 V. These measurements are taken at different operating points. For applications requiring specific gain characteristics, circuit performance should be evaluated against the actual operating conditions of your design.

Q: Is the lower transition frequency of the ZTX603STZ (150 MHz versus 200 MHz) a limitation?

A: For general-purpose switching and low-frequency amplification applications, the 150 MHz transition frequency of the ZTX603STZ is adequate. For circuits operating at frequencies approaching or exceeding 150 MHz, the frequency difference should be evaluated against specific circuit requirements.

Q: What is the significance of the higher power rating of the ZTX603STZ?

A: The ZTX603STZ supports 1 W maximum power dissipation compared to 625 mW for the BC373RL1G. This provides additional thermal margin in applications with sustained current or voltage stress, reducing the risk of thermal runaway and extending device lifetime.

Q: Are there any compliance or regulatory differences between these devices?

A: The ZTX603STZ carries ROHS3 compliance certification, meeting current environmental directives. Both devices maintain REACH Unaffected status and identical Moisture Sensitivity Level (MSL) ratings of 1 (Unlimited). The ZTX603STZ is the preferred choice for applications subject to RoHS compliance requirements.

Q: What is the operating temperature range difference?

A: The BC373RL1G operates from -55°C to 150°C (TJ). The ZTX603STZ operates from -55°C to 200°C (TJ). The extended upper temperature limit of the ZTX603STZ provides greater flexibility for applications in elevated-temperature environments.