BCW71_ND87Z Equivalent & Substitute Parts

Part Overview

The BCW71_ND87Z 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 and 500 mA maximum collector current, with a maximum power dissipation of 350 mW and transition frequency of 330 MHz. The BCW71_ND87Z is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production continuity. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and current availability.

Key Parameters

Parameter	BCW71_ND87Z	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	45	V
Current - Collector (Ic) (Max)	500	mA
Power - Max	350	mW
Frequency - Transition	330	MHz
Vce Saturation (Max) @ Ib, Ic	250 mV @ 500 µA, 10 mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	110 @ 2 mA, 5 V	—
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitute parts are grouped based on electrical parameter compatibility with the BCW71_ND87Z. The primary substitution criteria are:

Critical Parameters for Substitution:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown: minimum 45 V
Current - Collector (Ic) (Max): minimum 500 mA for full-current applications; lower ratings acceptable for reduced-current applications
Package / Case: SOT-23-3 (mechanical compatibility)
Mounting Type: Surface Mount (assembly compatibility)

Secondary Parameters:

Power dissipation capability
Transition frequency
DC current gain (hFE)
Vce saturation characteristics
Operating temperature range

Substitute parts are organized into two categories:

Category A - Full Current Rating Substitutes (500 mA): Parts maintaining the 500 mA collector current specification, suitable for direct replacement in applications requiring maximum current handling.

Category B - Reduced Current Rating Substitutes (100-200 mA): Parts with lower maximum collector current ratings, suitable for applications where the BCW71_ND87Z current capability exceeds circuit requirements.

All substitute parts listed are active products with current manufacturing status and RoHS3 compliance, ensuring long-term availability and regulatory compliance.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	Power mW	fT MHz	hFE (Min)	Status	Package
BCW71_ND87Z	onsemi	500	45	350	330	110	Obsolete	SOT-23-3
BC817-16LT1G	onsemi	500	45	300	100	100	Active	SOT-23-3
BC817-16LT3G	onsemi	500	45	300	100	100	Active	SOT-23-3
BC817-40LT1G	onsemi	500	45	300	100	250	Active	SOT-23-3
BC817-40LT3G	onsemi	500	45	300	100	250	Active	SOT-23-3
BCX19LT1G	onsemi	500	45	300	—	100	Active	SOT-23-3
BC847ALT1G	onsemi	100	45	300	100	110	Active	SOT-23-3
BC847CLT1G	onsemi	100	45	300	100	420	Active	SOT-23-3
BC847CLT3G	onsemi	100	45	300	100	420	Active	SOT-23-3
MMBT2222ALT1G	onsemi	600	40	225	300	100	Active	SOT-23-3
MMBT3904LT1G	onsemi	200	40	300	300	100	Active	SOT-23-3

Engineering Selection Recommendations

Category A - Full Current Rating Substitutes (500 mA Rated)

The BC817 series (BC817-16LT1G, BC817-16LT3G, BC817-40LT1G, BC817-40LT3G) and BCX19LT1G provide direct electrical substitution for the BCW71_ND87Z with maintained 500 mA collector current rating and 45 V breakdown voltage. These parts are active products with RoHS3 compliance. The BC817 variants differ in DC current gain specification: the -16 suffix denotes hFE minimum of 100, while the -40 suffix denotes hFE minimum of 250. Selection between these variants depends on circuit bias network requirements. The packaging suffix (LT1G indicates Cut Tape & Digi-Reel; LT3G indicates Tape & Reel) reflects distribution format only and does not affect electrical performance.

The BCX19LT1G offers equivalent electrical performance with 500 mA rating and 45 V breakdown voltage. This part lacks specified transition frequency data but maintains the same power dissipation and current gain characteristics.

Category B - Reduced Current Rating Substitutes (100-200 mA Rated)

The BC847 series (BC847ALT1G, BC847CLT1G, BC847CLT3G) and MMBT3904LT1G are suitable for applications where circuit current requirements do not exceed their maximum ratings. The BC847A variant specifies hFE minimum of 110, matching the BCW71_ND87Z gain specification. The BC847C variant specifies hFE minimum of 420, providing higher current gain. The MMBT3904LT1G provides 200 mA maximum current with 300 mW power dissipation and 300 MHz transition frequency.

Voltage Consideration

The MMBT2222ALT1G operates at 40 V maximum breakdown voltage, which is below the BCW71_ND87Z 45 V specification. This part is not suitable for applications requiring the full 45 V rating margin.

Product Status and Compliance

All recommended substitutes are active products with RoHS3 compliance and REACH unaffected status, ensuring regulatory compliance and long-term supply availability. The BC817 and BC847 series offer the highest inventory levels and widest distribution availability.

Frequently Asked Questions (FAQ)

Q: Can the BC817-16LT1G directly replace the BCW71_ND87Z?

A: Yes, the BC817-16LT1G is electrically compatible for direct replacement. Both parts share identical 45 V breakdown voltage, 500 mA maximum collector current, SOT-23-3 package, and similar DC current gain characteristics (hFE minimum 100 at specified test conditions). The BC817-16LT1G is an active product with current availability, addressing the obsolescence of the BCW71_ND87Z.

Q: What is the difference between BC817-16 and BC817-40 variants?

A: The primary difference is DC current gain specification. The BC817-16 variant specifies hFE minimum of 100 at 100 mA collector current and 1 V Vce. The BC817-40 variant specifies hFE minimum of 250 at the same test conditions. Selection depends on circuit bias network design. Higher gain (BC817-40) reduces base current requirements; lower gain (BC817-16) provides more conservative design margin.

Q: What is the difference between LT1G and LT3G packaging designations?

A: The packaging designation reflects distribution format only. LT1G indicates Cut Tape & Digi-Reel packaging; LT3G indicates Tape & Reel packaging. Both formats contain electrically identical components. Selection depends on assembly equipment compatibility and procurement volume requirements.

Q: Can the BC847ALT1G replace the BCW71_ND87Z in all applications?

A: The BC847ALT1G is suitable only for applications where maximum collector current does not exceed 100 mA. The BC847ALT1G maximum rating is 100 mA, compared to the BCW71_ND87Z 500 mA rating. For circuits requiring the full 500 mA capability, the BC847ALT1G is not suitable. For lower-current applications, the BC847ALT1G provides compatible electrical performance with 45 V breakdown voltage and matching hFE minimum of 110.

Q: Why is the MMBT2222ALT1G not recommended as a direct substitute?

A: The MMBT2222ALT1G operates at 40 V maximum breakdown voltage, which is below the BCW71_ND87Z 45 V specification. Applications designed for 45 V operation may exceed the MMBT2222ALT1G voltage rating. Additionally, the MMBT2222ALT1G maximum power dissipation is 225 mW, below the BCW71_ND87Z 350 mW rating. This part is suitable only for applications with voltage and power requirements within its specifications.

Q: What is the significance of transition frequency differences between substitute parts?

A: Transition frequency (fT) indicates the frequency at which transistor current gain drops to unity. The BCW71_ND87Z specifies 330 MHz transition frequency. The BC817 and BC847 series specify 100 MHz, and the MMBT2222ALT1G and MMBT3904LT1G specify 300 MHz. For applications operating at frequencies below the substitute part's transition frequency, the difference is not significant. For high-frequency applications approaching or exceeding 100 MHz, the MMBT3904LT1G (300 MHz) or MMBT2222ALT1G (300 MHz) provide closer performance matching to the BCW71_ND87Z.

Q: Are all substitute parts RoHS3 compliant?

A: Yes, all substitute parts listed are RoHS3 compliant and REACH unaffected. This ensures regulatory compliance for applications subject to RoHS3 requirements and provides long-term supply security.

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