BD135G Equivalent & Substitute Parts

Part Overview

The BD135G is an NPN bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 1.5 A maximum collector current in a TO-126 through-hole package. This device is actively produced and widely used in general-purpose switching and amplification applications.

Substitute parts become necessary when the BD135G reaches end-of-life status, when alternative packaging formats are required for manufacturing processes, or when inventory constraints necessitate functionally equivalent alternatives. The parts listed below maintain electrical equivalence across critical parameters while offering different packaging options, manufacturer sources, or product lifecycle statuses.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Max)	1.5	A
Collector-Emitter Breakdown Voltage (Max)	45	V
Vce Saturation (Max)	500	mV @ 50mA, 500mA
Collector Cutoff Current (Max)	100	nA
DC Current Gain (hFE Min)	40	@ 150mA, 2V
Power Dissipation (Max)	1.25	W
Operating Temperature Range	−55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-225AA, TO-126-3	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the BD135G is determined by strict equivalence across the following critical electrical and mechanical parameters:

Electrical Equivalence Criteria:

Transistor type: NPN
Collector current (Ic Max): 1.5 A
Collector-emitter breakdown voltage (Vceo Max): 45 V
Vce saturation: 500 mV @ 50mA, 500mA
Collector cutoff current (Icbo Max): 100 nA
Power dissipation: 1.25 W
Operating temperature range: minimum −55°C to 150°C

Mechanical Compatibility Criteria:

Mounting type: Through Hole
Package family: TO-126 or TO-126-3 (pin-compatible)

Acceptable Variations:

DC current gain (hFE) may vary within the specified range (40 minimum at 150mA, 2V) without affecting substitution eligibility
Packaging format (Bulk, Tube) does not affect electrical substitution but impacts procurement and handling
Manufacturer source (onsemi, STMicroelectronics) does not affect electrical equivalence
Product status variations (Active, Last Time Buy) indicate lifecycle position but do not prevent substitution

Parts that maintain all electrical parameters and through-hole mounting are classified as direct substitutes. Parts with identical electrical specifications but different package designations (SOT-32 vs. TO-126-3) remain mechanically compatible due to pin configuration equivalence.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vceo (Max)	Vce Sat (Max)	hFE (Min)	Power (Max)	Temp Range	Package	Status
BD135G	onsemi	1.5 A	45 V	500 mV	40	1.25 W	−55 to 150°C	TO-126	Active
BD135TG	onsemi	1.5 A	45 V	500 mV	40	1.25 W	−55 to 150°C	TO-126	Last Time Buy
BD13510STU	onsemi	1.5 A	45 V	500 mV	63	1.25 W	−55 to 150°C	TO-126-3	Active
BD13516S	onsemi	1.5 A	45 V	500 mV	100	1.25 W	−55 to 150°C	TO-126-3	Last Time Buy
BD13516STU	onsemi	1.5 A	45 V	500 mV	100	1.25 W	−55 to 150°C	TO-126-3	Active
BD135	STMicroelectronics	1.5 A	45 V	500 mV	40	1.25 W	−55 to 150°C	SOT-32-3	Active
BD135-16	STMicroelectronics	1.5 A	45 V	500 mV	40	1.25 W	−55 to 150°C	SOT-32	Not For New Designs

Engineering Selection Recommendations

Primary Substitutes (Recommended for New Designs):

BD13516STU and BD13510STU are the preferred substitutes for the BD135G. Both parts are manufactured by onsemi, maintain full electrical equivalence, carry Active product status, and are available in high inventory quantities. BD13516STU offers the highest DC current gain (hFE = 100), providing enhanced amplification characteristics while remaining within all specified electrical parameters. BD13510STU provides intermediate gain (hFE = 63). Both use the TO-126-3 package designation, which is pin-compatible with the original TO-126 package.

Secondary Substitutes (Acceptable for Existing Designs):

BD135TG is an onsemi-manufactured direct equivalent in TO-126 packaging with identical electrical specifications to the BD135G. However, its Last Time Buy status indicates limited future availability. This part is suitable for designs requiring exact package matching but should not be selected for new production programs.

BD135 (STMicroelectronics) maintains full electrical equivalence and Active product status with high inventory availability (26,500 units). The SOT-32-3 package is mechanically compatible with TO-126-3 pinouts. This part provides an alternative manufacturer source for supply chain diversification.

Not Recommended for New Designs:

BD135-16 carries a "Not For New Designs" status and should be used only for legacy system maintenance or repair applications where exact package matching to SOT-32 is required.

Compliance Considerations:

All substitute parts listed maintain ROHS3 compliance and REACH Unaffected status, matching the regulatory posture of the BD135G. Moisture sensitivity levels are either not applicable or rated MSL 1 (Unlimited), indicating no special handling requirements beyond standard component storage practices.

Frequently Asked Questions (FAQ)

Q: Can BD13516STU replace BD135G in existing circuit designs?

A: Yes. BD13516STU maintains electrical equivalence across all critical parameters: 1.5 A collector current, 45 V breakdown voltage, 500 mV saturation voltage, and 1.25 W power dissipation. The TO-126-3 package is pin-compatible with the TO-126 package used by BD135G. The higher DC current gain (hFE = 100 vs. 40) does not prevent substitution; it represents an improvement in amplification characteristics within the specified operating range.

Q: What is the difference between TO-126 and TO-126-3 packages?

A: Both designations refer to the same three-lead through-hole package with identical pin configuration and spacing. The "-3" suffix in TO-126-3 explicitly denotes the three-lead variant. These packages are mechanically and electrically interchangeable in PCB layouts designed for standard TO-126 components.

Q: Why do some substitute parts have higher hFE values?

A: DC current gain (hFE) variation is a normal characteristic of transistor manufacturing. Parts with hFE = 63 or hFE = 100 represent different production bins from the same base design. All values meet the minimum specification of 40 at 150 mA, 2 V. Higher gain values do not compromise circuit compatibility; they provide enhanced amplification margin and are acceptable substitutes.

Q: Is BD135 from STMicroelectronics equivalent to BD135G from onsemi?

A: Yes, electrically equivalent. Both maintain 1.5 A, 45 V, and 1.25 W specifications. The STMicroelectronics BD135 uses SOT-32-3 packaging, which is pin-compatible with TO-126-3. This part is suitable when manufacturer diversification is required for supply chain resilience. The STMicroelectronics version carries Active product status with 26,500 units in inventory.

Q: Should I use BD135TG for new production programs?

A: No. BD135TG carries Last Time Buy status, indicating limited future availability. While electrically identical to BD135G, this part should be reserved for legacy system support or repair applications only. For new designs, select BD13516STU or BD13510STU, both with Active status.

Q: Are there any thermal or operating condition differences between substitutes?

A: All substitute parts maintain the same operating temperature range (−55°C to 150°C junction temperature) and identical power dissipation limits (1.25 W). No thermal derating adjustments are required when substituting between listed parts.

Q: What packaging formats are available for substitutes?

A: BD135TG, BD13510STU, and BD13516STU are supplied in Tube packaging. BD13516S is supplied in Bulk packaging. BD135 and BD135-16 from STMicroelectronics are supplied in Tube packaging. Packaging format does not affect electrical performance; selection depends on procurement and assembly process requirements.

Q: Can I use BD135-16 as a substitute?

A: BD135-16 is electrically equivalent but carries "Not For New Designs" status. Use this part only for repair or maintenance of legacy systems where SOT-32 package matching is required. For all new production, select from the Active-status alternatives listed above.

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