BD436TG Equivalent & Substitute Parts Reference

Part Overview

The BD436TG is a PNP bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 4 A, collector-emitter breakdown voltage of 32 V, and maximum power dissipation of 36 W in a Through Hole TO-126 package. The BD436TG is classified as an obsolete product, making identification of suitable substitute components essential for ongoing design support, maintenance, and production continuity. Substitute parts must maintain functional equivalence across critical electrical parameters while accommodating packaging and availability constraints.

Substiute Parts

BD436TG

onsemiIn Stock: 915BD436TG Datasheet

Current PartRFQ

BD438

STMicroelectronicsIn Stock: 6538BD438 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BD436TG is determined by the following critical parameters:

Mandatory Matching Criteria:

• Transistor Type: PNP configuration
• Current - Collector (Ic) Max: 4 A minimum
• Power - Max: 36 W minimum
• Frequency - Transition: 3 MHz minimum
• Mounting Type: Through Hole
• Operating Temperature Range: Must encompass or exceed -55°C to 150°C

Allowable Variation Criteria:

• Voltage - Collector Emitter Breakdown: May exceed 32 V (higher voltage rating provides design margin)
• Vce Saturation: May vary within acceptable switching performance parameters
• DC Current Gain (hFE): May vary provided minimum gain supports circuit requirements
• Package / Case: Physical compatibility with TO-126 footprint or equivalent through-hole configuration
• Manufacturer: Alternative qualified manufacturers acceptable

The BD438 qualifies as a substitute based on matching or exceeding all mandatory criteria while providing enhanced voltage rating (45 V vs. 32 V) and maintained power dissipation (36 W).

Parameter Comparison

Engineering Selection Recommendations

BD438 as Primary Substitute:

The BD438 manufactured by STMicroelectronics is the qualified substitute for the obsolete BD436TG. Selection is based on the following engineering factors:

1. Electrical Equivalence: The BD438 maintains identical collector current (4 A), power dissipation (36 W), and transition frequency (3 MHz) specifications. The elevated voltage rating (45 V vs. 32 V) provides additional design margin without compromising circuit performance in applications rated for 32 V operation.

2. Product Status: The BD438 holds Active product status with confirmed inventory availability (6483 units in stock), ensuring long-term supply continuity compared to the obsolete BD436TG (850 units remaining).

3. Compliance & Certification: Both devices maintain identical REACH Status (REACH Unaffected) and ECCN classification (EAR99). The BD438 carries RoHS3 Compliance certification, meeting modern regulatory requirements. Moisture Sensitivity Level (MSL) is equivalent at Level 1 (Unlimited).

4. Package Compatibility: Both devices utilize through-hole mounting with compatible pin configurations (TO-126-3 and SOT-32-3 variants). Physical footprint compatibility must be verified for specific PCB layouts.

5. Thermal Performance: Both devices support operating temperatures to 150°C. The BD436TG specifies a lower limit of -55°C; the BD438 lower temperature limit is not provided in available documentation and must be confirmed for applications requiring sub-zero operation.

Frequently Asked Questions (FAQ)

Q: Can the BD438 directly replace the BD436TG in existing designs?

A: The BD438 is electrically compatible for applications operating at or below 32 V. The higher voltage rating (45 V) does not create incompatibility. Physical package verification is required; both use through-hole mounting but with different case designations (TO-126-3 vs. SOT-32-3). PCB footprint compatibility must be confirmed before substitution.

Q: What is the significance of the voltage rating difference (32 V vs. 45 V)?

A: The BD438's 45 V rating exceeds the BD436TG's 32 V specification. In applications designed for 32 V operation, the BD438 provides additional voltage margin without performance degradation. This is a conservative substitution. Applications requiring exactly 32 V operation are not compromised by a higher-rated component.

Q: Are there differences in DC current gain (hFE) between these devices?

A: Yes. The BD436TG specifies hFE minimum of 85 @ 500mA, 1V. The BD438 specifies hFE minimum of 30 @ 10mA, 5V. These measurements are taken at different operating points, making direct comparison invalid. Circuit designs must be verified to ensure adequate base drive with the BD438's gain characteristics at the intended operating point.

Q: What packaging considerations apply to substitution?

A: The BD436TG uses TO-225AA/TO-126-3 packaging; the BD438 uses SOT-32-3 packaging. Both are through-hole configurations with three leads (Base, Collector, Emitter). Pin assignment and physical dimensions differ. PCB layout modification may be required. Mechanical fit in existing sockets or PCB holes must be verified.

Q: Is the BD438 suitable for low-temperature applications below -55°C?

A: The BD436TG specifies operating temperature from -55°C to 150°C. The BD438 documentation provided does not specify a minimum operating temperature. For applications requiring operation below 0°C or at -55°C, the BD438's low-temperature performance must be confirmed with the manufacturer before substitution.

Q: What is the inventory status for each device?

A: The BD436TG (obsolete) has 850 units in stock. The BD438 (active product) has 6483 units in stock. For new designs or long-term production, the BD438 is recommended due to active manufacturing status and higher availability.

Q: Are there compliance or regulatory differences?

A: Both devices share identical REACH Status (REACH Unaffected), ECCN (EAR99), and HTSUS classification (8541.29.0095). The BD438 includes RoHS3 Compliance certification, which the BD436TG documentation does not specify. For applications requiring RoHS compliance, the BD438 is the appropriate choice.