BCX19 NPN Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The BCX19 is an NPN bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 500 mA maximum collector current in a surface mount SOT-23-3 package. The device is classified as obsolete, indicating discontinuation from active production. Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production builds and field replacements.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector Current (Ic) Maximum	500	mA
Collector-Emitter Breakdown Voltage (Max)	45	V
Vce Saturation @ Ib, Ic	620 mV @ 50 mA, 500 mA	—
Collector Cutoff Current (ICBO)	100	nA
DC Current Gain (hFE) Minimum @ Ic, Vce	100 @ 100 mA, 1 V	—
Power Dissipation Maximum	300	mW
Operating Temperature Range	−55 to 150	°C
Package Type	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the BCX19 are classified into two categories based on electrical and mechanical parameter alignment:

Direct Substitutes maintain identical or equivalent electrical specifications and package configuration, enabling pin-for-pin replacement without circuit modification:

BCX19LT1G: Active product status, identical electrical parameters, SOT-23-3 package, RoHS3 compliant
BC817-16LT1G: Active product status, 100 MHz transition frequency, SOT-23-3 package, RoHS3 compliant
SBC817-16LT3G: Active product status, automotive grade (AEC-Q101), 100 MHz transition frequency, SOT-23-3 package
SBCX19LT1G: Active product status, automotive grade (AEC-Q101), identical electrical parameters, SOT-23-3 package

Similar Parts share the same collector current, voltage rating, and package footprint but differ in secondary parameters such as transition frequency, DC current gain, or saturation voltage. These parts are functionally compatible in applications where the additional performance characteristics do not conflict with circuit requirements:

BC817-16LT3G: 100 MHz transition frequency, tape & reel packaging
BC817-25LT1G: 160 hFE minimum, 100 MHz transition frequency
BC817-25LT3G: 160 hFE minimum, 100 MHz transition frequency
BC817-40LT1G: 250 hFE minimum, 100 MHz transition frequency
BC817-40LT3G: 250 hFE minimum, 100 MHz transition frequency
50C02CH-TL-E: 50 V breakdown voltage, 500 MHz transition frequency, 700 mW power rating, 3-CPH package

Substitution is determined by matching the following critical parameters: transistor type (NPN), collector current rating (500 mA), collector-emitter breakdown voltage (45 V minimum), package type (SOT-23-3), and mounting configuration (surface mount).

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce(br) V	Vce Sat @ 50mA, 500mA mV	hFE Min @ 100mA, 1V	Power mW	Freq MHz	Temp °C	Package	RoHS
BCX19	onsemi	Obsolete	500	45	620	100	300	—	−55 to 150	SOT-23-3	—
BCX19LT1G	onsemi	Active	500	45	620	100	300	—	−55 to 150	SOT-23-3	ROHS3
BC817-16LT1G	onsemi	Active	500	45	700	100	300	100	−65 to 150	SOT-23-3	ROHS3
SBC817-16LT3G	onsemi	Active	500	45	700	100	300	100	−65 to 150	SOT-23-3	ROHS3
SBCX19LT1G	onsemi	Active	500	45	620	100	300	—	−55 to 150	SOT-23-3	ROHS3
BC817-16LT3G	onsemi	Active	500	45	700	100	300	100	−65 to 150	SOT-23-3	ROHS3
BC817-25LT1G	onsemi	Active	500	45	700	160	300	100	−65 to 150	SOT-23-3	ROHS3
BC817-25LT3G	onsemi	Active	500	45	700	160	300	100	−65 to 150	SOT-23-3	ROHS3
BC817-40LT1G	onsemi	Active	500	45	700	250	300	100	−65 to 150	SOT-23-3	ROHS3
BC817-40LT3G	onsemi	Active	500	45	700	250	300	100	−65 to 150	SOT-23-3	ROHS3
50C02CH-TL-E	onsemi	Active	500	50	100	300	700	500	−40 to 150	3-CPH	ROHS3

Engineering Selection Recommendations

Primary Recommendation: BCX19LT1G

BCX19LT1G is the direct functional equivalent of the obsolete BCX19. This part maintains identical electrical specifications including 620 mV saturation voltage at rated conditions, 100 hFE minimum gain, and −55 to 150 °C operating temperature range. The part is in active production status with RoHS3 compliance, ensuring long-term availability and regulatory alignment. Pin-for-pin compatibility with SOT-23-3 packaging eliminates circuit redesign requirements.

Secondary Recommendation: SBCX19LT1G

SBCX19LT1G provides identical electrical performance to BCX19LT1G with the addition of automotive-grade qualification (AEC-Q101). This variant is appropriate for applications requiring automotive reliability standards or extended supply chain assurance. The part maintains the same saturation voltage and current gain specifications as the original BCX19.

Alternative Recommendation: BC817-16LT1G or SBC817-16LT3G

BC817-16LT1G and SBC817-16LT3G are functionally compatible alternatives with 100 MHz transition frequency capability. These parts meet the core electrical requirements (500 mA, 45 V, 100 hFE minimum) and share the SOT-23-3 package footprint. The primary difference is saturation voltage (700 mV versus 620 mV), which is acceptable in most switching applications. SBC817-16LT3G includes automotive qualification for applications requiring AEC-Q101 compliance.

Higher Gain Alternatives: BC817-25LT1G, BC817-25LT3G, BC817-40LT1G, BC817-40LT3G

These variants provide higher DC current gain (160 or 250 hFE minimum) while maintaining identical voltage and current ratings. These parts are suitable for applications where increased gain reduces base drive requirements or improves switching speed. The 100 MHz transition frequency provides enhanced high-frequency performance compared to the original BCX19.

Limited Compatibility: 50C02CH-TL-E

50C02CH-TL-E shares the 500 mA collector current and SOT-23-3 package footprint but differs in package designation (3-CPH), breakdown voltage (50 V), saturation voltage (100 mV), and transition frequency (500 MHz). This part is suitable only for applications where the enhanced performance characteristics and higher voltage rating do not introduce design conflicts. The 3-CPH package may require PCB layout verification for compatibility.

Frequently Asked Questions (FAQ)

Q: Can BCX19LT1G directly replace the obsolete BCX19 without circuit modification?

A: Yes. BCX19LT1G is electrically and mechanically identical to BCX19, with matching saturation voltage (620 mV), current gain (100 hFE minimum), and operating temperature range (−55 to 150 °C). The SOT-23-3 package footprint is identical, enabling direct substitution.

Q: What is the difference between BC817-16LT1G and BCX19LT1G?

A: Both parts meet the core electrical requirements (500 mA, 45 V, 100 hFE minimum, SOT-23-3 package). BC817-16LT1G includes 100 MHz transition frequency and exhibits 700 mV saturation voltage compared to 620 mV for BCX19LT1G. The higher saturation voltage is acceptable in most switching circuits and may improve switching speed in high-frequency applications.

Q: Are automotive-grade variants (SBCX19LT1G, SBC817-16LT3G) required for non-automotive applications?

A: Automotive-grade variants are not required for non-automotive applications. These parts include AEC-Q101 qualification, which adds manufacturing process controls and reliability testing. Selection depends on application requirements and supply chain preferences. Standard commercial-grade parts (BCX19LT1G, BC817-16LT1G) are suitable for general-purpose applications.

Q: What is the significance of the hFE suffix in BC817 part numbers (16, 25, 40)?

A: The hFE suffix indicates the minimum DC current gain specification. BC817-16 specifies 100 hFE minimum, BC817-25 specifies 160 hFE minimum, and BC817-40 specifies 250 hFE minimum. Higher gain variants reduce base drive current requirements and improve switching performance in applications sensitive to gain variation.

Q: Can BC817-40LT1G replace BCX19 in all applications?

A: BC817-40LT1G is electrically compatible with BCX19 for applications where higher DC current gain (250 hFE minimum versus 100 hFE) does not introduce circuit instability or excessive switching speed. The 100 MHz transition frequency and 700 mV saturation voltage are acceptable in most switching applications. Circuit simulation or bench testing is appropriate for gain-sensitive applications.

Q: What is the difference between Cut Tape (CT) and Tape & Reel (TR) packaging?

A: Cut Tape packaging supplies individual components on carrier tape suitable for manual assembly or small-volume production. Tape & Reel packaging supplies components on continuous reel suitable for automated pick-and-place assembly. Both packaging formats contain identical components; selection depends on assembly process requirements and volume.

Q: Is 50C02CH-TL-E a suitable replacement for BCX19?

A: 50C02CH-TL-E is functionally compatible only in applications where the enhanced specifications (50 V breakdown voltage, 500 MHz transition frequency, 700 mW power rating) do not conflict with circuit design. The 3-CPH package differs from SOT-23-3, requiring PCB layout verification. The 100 mV saturation voltage is significantly lower than BCX19, which may affect switching characteristics in saturation-mode applications.

Q: What does RoHS3 compliance indicate?

A: RoHS3 compliance indicates conformance to the Restriction of Hazardous Substances Directive, restricting lead, cadmium, mercury, and other hazardous materials in electronic components. All recommended substitute parts carry RoHS3 compliance, ensuring regulatory alignment with current environmental standards.

Q: Can I use BC817-25LT3G instead of BC817-25LT1G?

A: Yes. Both parts are electrically identical with 160 hFE minimum gain, 100 MHz transition frequency, and 45 V rating. The difference is packaging format: LT1G is Cut Tape, and LT3G is Tape & Reel. Selection depends on assembly process requirements.

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