BCX70K Equivalent & Substitute Parts

Part Overview

The BCX70K is an NPN bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 45 V collector-emitter breakdown voltage with a maximum collector current of 200 mA and 350 mW power dissipation. The BCX70K is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and continued availability.

Key Parameters

Parameter	BCX70K Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	45	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	350	mW
Frequency - Transition	125	MHz
Vce Saturation (Max) @ Ib, Ic	550mV @ 1.25mA, 50mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	380 @ 2mA, 5V	—
Current - Collector Cutoff (Max)	20	nA
Package / Case	SOT-23-3 (TO-236)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the BCX70K are selected based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Matching Parameters:

Transistor Type: NPN (all substitutes must be NPN)
Package / Case: SOT-23-3 (TO-236) surface mount (all substitutes must use identical package)
Voltage - Collector Emitter Breakdown (Max): 45 V minimum (substitutes rated at 45 V or higher are acceptable)
Current - Collector (Ic) (Max): 200 mA minimum (substitutes rated at 200 mA or higher are acceptable)
Power - Max: 350 mW minimum (substitutes rated at 350 mW or higher are acceptable)
RoHS Status: ROHS3 Compliant (all substitutes must maintain compliance)
Moisture Sensitivity Level (MSL): 1 (Unlimited) (all substitutes must match or exceed this rating)

Substitutes are grouped into two categories based on electrical performance:

Category A - Direct Current Replacement (200 mA rated): Parts with maximum collector current of 200 mA, suitable for applications requiring exact current matching to the BCX70K.

Category B - Enhanced Current Capability (500 mA rated): Parts with maximum collector current of 500 mA or higher, suitable for applications where increased current headroom is beneficial or where the BCX70K's 200 mA rating is marginal.

Category C - Alternative Voltage/Current Profile (40 V, 600 mA rated): Parts with reduced voltage rating (40 V) but enhanced current capability, suitable only for applications where 40 V breakdown voltage is sufficient.

Parameter Comparison

Part Number	Manufacturer	Transistor Type	Ic (Max) mA	Vce(br) (Max) V	Power (Max) mW	Frequency (Transition) MHz	Vce Sat (Max) mV	hFE (Min)	Package	Product Status
BCX70K	onsemi	NPN	200	45	350	125	550 @ 1.25mA, 50mA	380 @ 2mA, 5V	SOT-23-3	Obsolete
BC817-16LT1G	onsemi	NPN	500	45	300	100	700 @ 50mA, 500mA	100 @ 100mA, 1V	SOT-23-3	Active
BC847CLT1G	onsemi	NPN	100	45	300	100	600 @ 5mA, 100mA	420 @ 2mA, 5V	SOT-23-3	Active
BCX19LT1G	onsemi	NPN	500	45	300	—	620 @ 50mA, 500mA	100 @ 100mA, 1V	SOT-23-3	Active
MMBT2222ALT1G	onsemi	NPN	600	40	225	300	1000 @ 50mA, 500mA	100 @ 150mA, 10V	SOT-23-3	Active
MMBT2222ALT3G	onsemi	NPN	600	40	300	300	1000 @ 50mA, 500mA	100 @ 150mA, 10V	SOT-23-3	Active
MMBT6429LT1G	onsemi	NPN	200	45	225	700	600 @ 5mA, 100mA	500 @ 100µA, 5V	SOT-23-3	Active
SBC817-25LT1G	onsemi	NPN	500	45	300	100	700 @ 50mA, 500mA	160 @ 100mA, 1V	SOT-23-3	Active
SBC817-25LT3G	onsemi	NPN	500	45	300	100	700 @ 50mA, 500mA	160 @ 100mA, 1V	SOT-23-3	Active
SBC817-40LT1G	onsemi	NPN	500	45	300	100	700 @ 50mA, 500mA	250 @ 100mA, 1V	SOT-23-3	Active
SBC817-40LT3G	onsemi	NPN	500	45	300	100	700 @ 50mA, 500mA	250 @ 100mA, 1V	SOT-23-3	Active

Engineering Selection Recommendations

Category A - Direct Current Replacement (200 mA Rated):

MMBT6429LT1G is the only active substitute with identical 200 mA maximum collector current rating. This part maintains 45 V breakdown voltage, SOT-23-3 package compatibility, and ROHS3 compliance. The MMBT6429LT1G offers superior transition frequency (700 MHz versus 125 MHz) and higher DC current gain (500 @ 100µA, 5V versus 380 @ 2mA, 5V), with reduced power dissipation (225 mW versus 350 mW). This part is suitable for direct replacement in applications where the 200 mA current rating is a design requirement.

Category B - Enhanced Current Capability (500 mA Rated):

BC817-16LT1G, BCX19LT1G, SBC817-25LT1G, SBC817-25LT3G, SBC817-40LT1G, and SBC817-40LT3G all provide 500 mA maximum collector current with 45 V breakdown voltage and SOT-23-3 package compatibility. These parts are suitable for applications where the BCX70K's 200 mA rating is marginal or where increased current headroom is beneficial. The SBC817 variants include automotive qualification (AEC-Q101) and are available in both cut tape and tape & reel packaging options. The BC817-16LT1G and BCX19LT1G offer standard commercial grade alternatives.

Category C - Alternative Voltage/Current Profile (40 V, 600 mA Rated):

MMBT2222ALT1G and MMBT2222ALT3G provide 600 mA maximum collector current but with reduced 40 V breakdown voltage. These parts are suitable only for applications where 40 V breakdown voltage is sufficient. MMBT2222ALT1G includes automotive qualification (AEC-Q101). The MMBT2222ALT3G offers increased power dissipation (300 mW versus 225 mW in the ALT1G variant) and is available with higher inventory levels.

Product Status Consideration:

All substitute parts listed maintain active product status with onsemi, ensuring continued availability and supply chain stability. The BCX70K's obsolete status necessitates migration to one of these active alternatives for new designs and production continuity.

Frequently Asked Questions (FAQ)

Q: Can BC847CLT1G replace BCX70K in all applications?

A: BC847CLT1G is not a suitable direct replacement. While it maintains the same 45 V breakdown voltage and SOT-23-3 package, its maximum collector current rating is 100 mA, which is below the BCX70K's 200 mA specification. This part is suitable only for applications where collector current does not exceed 100 mA.

Q: What is the primary difference between MMBT6429LT1G and BCX70K?

A: MMBT6429LT1G matches the BCX70K's 200 mA collector current and 45 V breakdown voltage specifications. The primary differences are enhanced transition frequency (700 MHz versus 125 MHz), higher DC current gain (500 @ 100µA, 5V versus 380 @ 2mA, 5V), and reduced power dissipation (225 mW versus 350 mW). These differences represent performance improvements suitable for direct replacement.

Q: Are SBC817 variants suitable for non-automotive applications?

A: Yes. SBC817 variants include automotive qualification (AEC-Q101) but are suitable for general commercial applications. The automotive qualification represents an additional compliance level and does not restrict use in non-automotive designs. These parts offer the same electrical performance as their non-automotive equivalents.

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

A: Both parts provide 500 mA collector current and 45 V breakdown voltage in SOT-23-3 packages. BC817-16LT1G specifies 100 MHz transition frequency, while BCX19LT1G does not specify transition frequency in the provided data. BC817-16LT1G is available in higher inventory quantities (305,400 pcs versus 110,100 pcs).

Q: Can MMBT2222ALT1G or MMBT2222ALT3G replace BCX70K?

A: MMBT2222ALT1G and MMBT2222ALT3G are not suitable direct replacements. These parts have reduced breakdown voltage (40 V versus 45 V) and are suitable only for applications where 40 V breakdown voltage is sufficient. Use these parts only when the application voltage requirements do not exceed 40 V.

Q: What packaging options are available for substitute parts?

A: All substitute parts use SOT-23-3 (TO-236) surface mount packages, matching the BCX70K package specification. Packaging format options include Cut Tape (CT) & Digi-Reel®, Tape & Reel (TR), and standard reel configurations. Specific packaging format availability varies by part number and should be confirmed with the supplier.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and Moisture Sensitivity Level 1 (Unlimited), matching the BCX70K environmental and regulatory specifications.

Q: Which substitute part offers the highest transition frequency?

A: MMBT6429LT1G offers the highest transition frequency at 700 MHz, compared to the BCX70K's 125 MHz. This enhanced frequency performance is combined with 200 mA collector current matching, making MMBT6429LT1G suitable for high-frequency applications requiring direct current replacement.

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