BC818-25 Equivalent & Substitute Parts

Part Overview

The BC818-25 is an NPN bipolar junction transistor (BJT) manufactured by Diotec Semiconductor in SOT-23-3 surface mount packaging. This device is rated for 25 V collector-emitter breakdown voltage with a maximum collector current of 800 mA and 310 mW power dissipation. The BC818-25 is classified as an active product and is suitable for general-purpose switching and amplification applications in consumer and industrial electronics. Equivalent and substitute parts are identified to provide design flexibility, support supply chain continuity, and accommodate component availability variations.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Max)	800	mA
Collector-Emitter Breakdown Voltage (Max)	25	V
Power Dissipation (Max)	310	mW
Transition Frequency	100	MHz
DC Current Gain (hFE Min)	160	@ 100 mA, 1 V
Operating Temperature Range	−55 to 150	°C
Package Type	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitute parts for the BC818-25 are identified based on electrical and mechanical parameter compatibility. The primary substitution criteria are:

Electrical Compatibility Parameters:

Transistor type classification (NPN)
Maximum collector current rating (800 mA minimum)
Collector-emitter breakdown voltage (25 V minimum)
DC current gain (hFE ≥ 160 @ 100 mA, 1 V)
Collector cutoff current (ICBO ≤ 100 nA)

Mechanical Compatibility Parameters:

Package type (SOT-23-3 / TO-236-3 / SC-59)
Surface mount mounting type
Pin configuration and footprint equivalence

Product Status Criteria:

Active product status
Compliance certifications (RoHS, REACH where applicable)

The KSC3265YMTF meets all electrical and mechanical compatibility requirements for direct substitution with the BC818-25 in circuit applications where the specified parameters are within design tolerances.

Parameter Comparison

Parameter	BC818-25 (Diotec)	KSC3265YMTF (onsemi)	Unit
Transistor Type	NPN	NPN	—
Collector Current (Max)	800	800	mA
Collector-Emitter Breakdown Voltage (Max)	25	25	V
Vce Saturation (Max)	700 mV @ 50 mA, 500 mA	400 mV @ 20 mA, 500 mA	V
Collector Cutoff Current (Max)	100	100	nA
DC Current Gain (hFE Min)	160 @ 100 mA, 1 V	160 @ 100 mA, 1 V	—
Power Dissipation (Max)	310	200	mW
Transition Frequency	100	120	MHz
Operating Temperature (Max)	150	150	°C
Package Type	SOT-23-3	SOT-23-3	—
Mounting Type	Surface Mount	Surface Mount	—
Product Status	Active	Active	—

Engineering Selection Recommendations

BC818-25 (Diotec Semiconductor): The BC818-25 is suitable for applications requiring the specified 310 mW power dissipation rating. This device is active and available in high inventory (1300 pcs). RoHS status is not applicable for this part.

KSC3265YMTF (onsemi): The KSC3265YMTF is a direct electrical substitute with identical collector current, breakdown voltage, and DC current gain specifications. This device offers superior saturation voltage performance (400 mV vs. 700 mV) and higher transition frequency (120 MHz vs. 100 MHz). The KSC3265YMTF is RoHS3 compliant and REACH unaffected, with moisture sensitivity level MSL-1 (unlimited). Inventory availability is significantly higher (40,400 pcs). The maximum power dissipation is 200 mW, which is lower than the BC818-25; circuit designs must verify that thermal requirements do not exceed this rating.

Both devices are active products in SOT-23-3 packaging suitable for surface mount assembly. Selection between these parts depends on power dissipation requirements, compliance certifications needed for the end application, and supply chain availability.

Frequently Asked Questions (FAQ)

Q: Can the KSC3265YMTF replace the BC818-25 in all applications?

A: The KSC3265YMTF is electrically compatible for applications where the maximum power dissipation does not exceed 200 mW. The BC818-25 is rated for 310 mW. If your circuit design requires power dissipation above 200 mW, the KSC3265YMTF is not suitable. For applications within the 200 mW limit, the KSC3265YMTF provides equivalent or superior electrical performance.

Q: Are the packages identical?

A: Yes. Both the BC818-25 and KSC3265YMTF use the SOT-23-3 package (also designated TO-236-3 or SC-59). The footprint, pin configuration, and mounting requirements are identical for surface mount assembly.

Q: What is the difference in saturation voltage between these parts?

A: The BC818-25 has a maximum saturation voltage of 700 mV at 50 mA collector current and 500 mA base current. The KSC3265YMTF has a maximum saturation voltage of 400 mV at 20 mA collector current and 500 mA base current. The KSC3265YMTF exhibits lower saturation voltage, which may reduce power dissipation in switching applications.

Q: Do both parts have the same DC current gain?

A: Yes. Both devices specify a minimum DC current gain (hFE) of 160 at 100 mA collector current and 1 V collector-emitter voltage.

Q: What are the compliance differences?

A: The KSC3265YMTF is RoHS3 compliant and REACH unaffected with MSL-1 moisture sensitivity. The BC818-25 does not specify RoHS or REACH status. If your application requires RoHS or REACH compliance, the KSC3265YMTF is the appropriate choice.

Q: Can I use the BC818-25 as a substitute for the KSC3265YMTF?

A: The BC818-25 can substitute for the KSC3265YMTF in applications where the higher power dissipation rating (310 mW vs. 200 mW) is beneficial or required. All other electrical parameters are compatible. Verify that compliance certifications (RoHS, REACH) are not required for your application, as the BC818-25 does not specify these certifications.

Q: What is the operating temperature range for both parts?

A: Both devices operate from −55°C to 150°C junction temperature. The maximum operating temperature is identical for both parts.

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