MSB1218A-RT1 PNP Bipolar Transistor Equivalent & Substitute Parts

Part Overview

The MSB1218A-RT1 is a PNP bipolar junction transistor manufactured by onsemi, rated for 45 V collector-emitter breakdown voltage and 100 mA maximum collector current in a surface mount SC-70 (SOT-323) package. This component is classified as obsolete product status. Identification of equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for production and repair applications. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Substiute Parts

MSB1218A-RT1

onsemiIn Stock: 2845MSB1218A-RT1 Datasheet

Current PartRFQ

MSB1218A-RT1G

onsemiIn Stock: 18588MSB1218A-RT1G Datasheet

DirectRFQ

BC857BW-G

Comchip TechnologyIn Stock: 943BC857BW-G Datasheet

DirectRFQ

BC857CW-G

Comchip TechnologyIn Stock: 1214BC857CW-G Datasheet

DirectRFQ

2PB709ARW,115

NXP USA Inc.In Stock: 190262PB709ARW,115 Datasheet

SimilarRFQ

2PB709ASW,115

NXP USA Inc.In Stock: 3240802PB709ASW,115 Datasheet

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AC857CWQ-7

Diodes IncorporatedIn Stock: 859AC857CWQ-7 Datasheet

SimilarRFQ

BC857AW,115

NXP SemiconductorsIn Stock: 280093BC857AW,115 Datasheet

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BC857W,135

NXP USA Inc.In Stock: 1230862BC857W,135 Datasheet

SimilarRFQ

BC860BW,135

Nexperia USA Inc.In Stock: 10689BC860BW,135 Datasheet

SimilarRFQ

BC860CW,115

Nexperia USA Inc.In Stock: 13117BC860CW,115 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MSB1218A-RT1 are classified into two categories based on electrical and mechanical compatibility:

Direct Substitutes maintain identical electrical specifications and package configuration, differing only in packaging format (Tape & Reel versus bulk) or RoHS compliance status.

Similar Substitutes maintain the core electrical parameters (PNP type, 45 V breakdown voltage, 100 mA collector current, SOT-323 package) but may include enhancements such as higher power dissipation, increased transition frequency, or automotive-grade qualification. These parts are electrically compatible within the application envelope of the original component.

Substitution compatibility is determined by the following parameters:

• Transistor polarity (PNP)
• Maximum collector current (100 mA minimum)
• Collector-emitter breakdown voltage (45 V minimum)
• Package type (SC-70 / SOT-323)
• Vce saturation characteristics
• DC current gain (hFE) specifications

Parameter Comparison

Engineering Selection Recommendations

Direct Replacement Priority:

MSB1218A-RT1G is the primary direct substitute. This part is manufactured by onsemi (original manufacturer), maintains identical electrical specifications, and carries Active product status. MSB1218A-RT1G is RoHS3 compliant, whereas the original MSB1218A-RT1 is RoHS non-compliant. Both parts are REACH Unaffected and carry MSL 1 (Unlimited) moisture sensitivity rating.

Active Substitute Selection:

For applications requiring active product status with extended availability, the following parts provide electrical compatibility:

2PB709ARW,115 and 2PB709ASW,115 (NXP USA Inc.) maintain identical Vce saturation characteristics (500 mV @ 10 mA, 100 mA) and DC current gain specifications matching the original part. Both carry automotive-grade qualification (AEC-Q101) and offer higher power dissipation (200 mW versus 150 mW). 2PB709ASW,115 provides higher DC current gain (290 @ 2 mA, 10 V) and transition frequency (80 MHz).

BC857CW-G and BC860CW,115 (Comchip Technology and Nexperia USA Inc.) provide higher DC current gain (420 @ 2 mA, 5 V) and transition frequency (100 MHz) with increased power dissipation (150 mW and 200 mW respectively). Vce saturation is elevated to 650 mV @ 5 mA, 100 mA.

AC857CWQ-7 (Diodes Incorporated) combines automotive-grade qualification (AEC-Q101), 100 MHz transition frequency, and 200 mW power dissipation with RoHS3 compliance.

BC857AW,115 and BC857W,135 (NXP Semiconductors and NXP USA Inc.) provide automotive-grade qualification and 100 MHz transition frequency but feature lower DC current gain (125 @ 2 mA, 5 V) and elevated Vce saturation (600 mV @ 5 mA, 100 mA).

Frequently Asked Questions (FAQ)

Q: Can MSB1218A-RT1G be used as a direct replacement for MSB1218A-RT1?

A: Yes. MSB1218A-RT1G is manufactured by onsemi and maintains identical electrical specifications including collector current (100 mA), breakdown voltage (45 V), Vce saturation (500 mV @ 10 mA, 100 mA), and DC current gain (210 @ 2 mA, 10 V). The primary difference is packaging format (Tape & Reel versus bulk) and RoHS compliance status (RoHS3 Compliant versus RoHS non-compliant). Both use SOT-323 package.

Q: What is the difference between BC857CW-G and BC860CW,115?

A: Both parts are PNP transistors in SOT-323 package with 100 mA collector current and 45 V breakdown voltage. BC857CW-G is manufactured by Comchip Technology, while BC860CW,115 is manufactured by Nexperia USA Inc. Both provide identical DC current gain (420 @ 2 mA, 5 V) and transition frequency (100 MHz). BC860CW,115 carries automotive-grade qualification (AEC-Q101) and offers 200 mW power dissipation versus BC857CW-G at 150 mW. Vce saturation is 650 mV @ 5 mA, 100 mA for both parts.

Q: Are NXP 2PB709ARW,115 and 2PB709ASW,115 interchangeable?

A: Both parts are automotive-grade PNP transistors with 100 mA collector current, 45 V breakdown voltage, and SOT-323 package. 2PB709ARW,115 provides 70 MHz transition frequency with DC current gain of 210 @ 2 mA, 10 V. 2PB709ASW,115 provides 80 MHz transition frequency with higher DC current gain of 290 @ 2 mA, 10 V. Both maintain identical Vce saturation (500 mV @ 10 mA, 100 mA) and 200 mW power dissipation. Selection depends on frequency and gain requirements of the application.

Q: What is the significance of Vce saturation differences among substitute parts?

A: Vce saturation determines the voltage drop across the transistor when operating in saturation mode. The original MSB1218A-RT1 specifies 500 mV @ 10 mA, 100 mA. Substitute parts BC857BW-G, BC857CW-G, BC860BW,135, BC860CW,115, and AC857CWQ-7 specify 650 mV @ 5 mA, 100 mA, representing higher saturation voltage. BC857AW,115 and BC857W,135 specify 600 mV @ 5 mA, 100 mA. Applications sensitive to saturation voltage drop require verification that the higher saturation values do not exceed circuit design margins.

Q: Which substitute parts carry automotive qualification?

A: The following parts carry AEC-Q101 automotive qualification: 2PB709ARW,115, 2PB709ASW,115, AC857CWQ-7, BC857AW,115, BC857W,135, BC860BW,135, and BC860CW,115. These parts are suitable for automotive applications requiring automotive-grade component certification.

Q: Are all substitute parts RoHS3 compliant?

A: No. MSB1218A-RT1 is RoHS non-compliant. MSB1218A-RT1G is RoHS3 compliant. BC857BW-G, BC857CW-G, AC857CWQ-7, BC860BW,135, and BC860CW,115 are RoHS3 compliant. 2PB709ARW,115, 2PB709ASW,115, BC857AW,115, and BC857W,135 do not specify RoHS status in provided data. Verify RoHS compliance requirements for your application before selection.

Q: What is the difference between bulk and Tape & Reel packaging?

A: Bulk packaging is supplied in loose form, suitable for manual assembly or small-quantity applications. Tape & Reel packaging is supplied on continuous tape for automated pick-and-place assembly equipment. MSB1218A-RT1 is supplied in bulk. MSB1218A-RT1G, BC857BW-G, BC857CW-G, AC857CWQ-7, BC860BW,135, and BC860CW,115 are supplied in Tape & Reel format. 2PB709ARW,115, 2PB709ASW,115, BC857AW,115, and BC857W,135 are supplied in bulk. Packaging selection depends on assembly process requirements.

Q: Can parts with higher power dissipation (200 mW) replace the original 150 mW part?

A: Yes. Higher power dissipation rating indicates the part can handle greater thermal load. A 200 mW rated part can safely operate in applications designed for 150 mW parts. However, the reverse substitution (150 mW part replacing 200 mW requirement) is not valid. Verify that thermal management and PCB layout accommodate the substitute part's thermal characteristics.