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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi MSB1218A-RT1

Name: MSB1218A-RT1
Brand: onsemi
SKU: MSB1218A-RT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MSB1218A-RT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: SC-70, SOT-323

Datasheet:: MSB1218A-RT1.pdf

Description:: TRANS PNP 45V 0.1A SC70-3

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Product details

Overview

MSB1218A-RT1 from onsemi is a PNP silicon epitaxial planar transistor designed for general-purpose amplifier applications, featuring h_FE of 210–340 at I_C = 2.0 mA, V_CE(sat) ≤ 0.5 V at I_C = 100 mA/I_B = 10 mA, and V_(BR)CEO = 45 V, commonly used in low-power audio preamplifier stages and signal-level switching circuits.

For engineers reviewing the MSB1218A-RT1 datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain consistency across temperature, low saturation voltage for efficient biasing in Class-A amplifiers, and SC-70 package thermal performance under continuous 100 mA operation.

Technical Context

This PNP bipolar junction transistor operates with emitter-base forward bias and collector-base reverse bias in active amplifier mode. Its h_FE range (210–340) is specified at V_CE = 10 V and I_C = 2.0 mA, and it maintains V_CE(sat) ≤ 0.5 V under forced β = 10 conditions.

The device supports continuous collector current up to 100 mA with 150 mW power dissipation on FR-4 PCB, and its breakdown ratings-V_(BR)CBO, V_(BR)CEO, and V_(BR)EBO-are all tested per JEDEC JESD22-A114 with defined leakage limits (I_CBO ≤ 0.1 µA, I_CEO ≤ 100 µA).

Key Specifications

Parameter	Value and Actual Design Meaning
V_(BR)CEO	45 V - Maximum allowable collector-emitter voltage before avalanche breakdown under open-base condition
h_FE	210–340 - DC current gain at V_CE = 10 V, I_C = 2.0 mA; determines small-signal amplification capability
V_CE(sat)	≤ 0.5 V - Collector-emitter saturation voltage at I_C = 100 mA, I_B = 10 mA; enables low-loss switching and efficient bias design
P_D	150 mW - Maximum power dissipation on FR-4 board with minimum footprint; constrains thermal design margin
I_C (continuous)	100 mA - Rated DC collector current; defines upper limit for linear amplifier or switch operation without derating
T_J	150 °C - Maximum junction temperature; sets thermal boundary for reliability under sustained load

Pinout & Package

MSB1218A-RT1 is housed in the SC-70 (SOT-323) surface-mount package (Case 419, Style 7), with 3 terminals and a 1.25 mm × 2.1 mm footprint. Thermal resistance R_JA is 833 °C/W on FR-4.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased p-n junction; requires current-limited drive to achieve target h_FE-based amplification
2	Emiter	Current source terminal in PNP configuration; connected to higher potential rail in common-emitter amplifier layouts
3	Collector	Output terminal where amplified current flows; reverse-biased relative to base in active region operation

Key Features

Feature	Design Value
High DC current gain	h_FE = 210–340 at I_C = 2.0 mA ensures stable small-signal voltage amplification with minimal base drive current
Low saturation voltage	V_CE(sat) ≤ 0.5 V at I_C = 100 mA/I_B = 10 mA reduces conduction loss in switching and Class-A output stages
Pb-Free, RoHS-compliant	Meets EU Directive 2011/65/EU and halogen-free/BFR-free requirements for environmentally regulated end equipment
SC-70 thermal performance	150 mW power rating with R_JA = 833 °C/W enables use in space-constrained, low-power analog modules without heatsinking

Applications

Audio Preamp Stage	Level Shifting Circuit
Use Scenario: Low-noise voltage amplification of microphone or line-level signals in portable audio devices. IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide non-inverting gain with high input impedance. Use Value: h_FE ≥ 210 ensures sufficient gain margin at 2.0 mA bias, while V_CE(sat) ≤ 0.5 V minimizes distortion in single-supply Class-A operation.	Use Scenario: Translating logic-level signals between incompatible voltage domains (e.g., 5 V microcontroller to 3.3 V sensor interface). IC Role / Device Role / Timing Role: Active pull-up/pull-down switch operating in saturation/cutoff regions for bidirectional level translation. Use Value: V_(BR)EBO = 7.0 V allows safe operation with 5 V base drive; 100 mA I_C rating supports robust sink/source capability.
Current Mirror Reference	LED Driver Switch
Use Scenario: Precision current replication in analog front-ends or sensor biasing networks. IC Role / Device Role / Timing Role: Matched PNP transistor in emitter-coupled pair to establish stable reference current proportional to input. Use Value: Tight h_FE spread (210–340) and low V_CE(sat) improve mirror accuracy and reduce compliance voltage headroom.	Use Scenario: Constant-current switching for indicator LEDs in industrial control panels. IC Role / Device Role / Timing Role: Low-side or high-side switch controlling LED anode/cathode connection via base current modulation. Use Value: 45 V V_(BR)CEO accommodates transient spikes in 24 V systems; 150 mW PD supports continuous 20 mA LED drive without thermal throttling.

Audio Preamp Stage

Level Shifting Circuit

Use Scenario: Low-noise voltage amplification of microphone or line-level signals in portable audio devices.

IC Role / Device Role / Timing Role: PNP BJT configured in common-emitter topology to provide non-inverting gain with high input impedance.

Use Value: h_FE ≥ 210 ensures sufficient gain margin at 2.0 mA bias, while V_CE(sat) ≤ 0.5 V minimizes distortion in single-supply Class-A operation.

Use Scenario: Translating logic-level signals between incompatible voltage domains (e.g., 5 V microcontroller to 3.3 V sensor interface).

IC Role / Device Role / Timing Role: Active pull-up/pull-down switch operating in saturation/cutoff regions for bidirectional level translation.

Use Value: V_(BR)EBO = 7.0 V allows safe operation with 5 V base drive; 100 mA I_C rating supports robust sink/source capability.

Current Mirror Reference

LED Driver Switch

Use Scenario: Precision current replication in analog front-ends or sensor biasing networks.

IC Role / Device Role / Timing Role: Matched PNP transistor in emitter-coupled pair to establish stable reference current proportional to input.

Use Value: Tight h_FE spread (210–340) and low V_CE(sat) improve mirror accuracy and reduce compliance voltage headroom.

Use Scenario: Constant-current switching for indicator LEDs in industrial control panels.

IC Role / Device Role / Timing Role: Low-side or high-side switch controlling LED anode/cathode connection via base current modulation.

Use Value: 45 V V_(BR)CEO accommodates transient spikes in 24 V systems; 150 mW PD supports continuous 20 mA LED drive without thermal throttling.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose amplifier applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT3906LT1G	h_FE = 100–300 (lower min), V_CE(sat) ≤ 0.4 V (slightly lower), same SC-70 package	Suitable for lower-gain, higher-efficiency switching; less margin for low-I_C amplification stability	Select when prioritizing saturation loss over gain consistency at microampere base currents
PN2907A	TO-92 through-hole package, h_FE = 100–300, V_CE(sat) ≤ 0.6 V, higher PD (625 mW)	Used in prototyping or legacy through-hole designs; not drop-in compatible due to package and thermal profile	Choose for manual assembly, higher-power test fixtures, or where board real estate permits larger footprint

Compared with MMBT3906LT1G and PN2907A, MSB1218A-RT1 offers superior h_FE minimum (210 vs. 100) for stable low-current amplification, tighter V_CE(sat) control at 100 mA, and optimized SC-70 thermal behavior for high-density SMT production.

Availability

MSB1218A-RT1 is available at Aetrix Electronics and suitable for audio preamplifier stages, level-shifting interfaces, current mirror references, and LED driver switches requiring stable component supply in high-volume consumer and industrial electronics.

Supply support for MSB1218A-RT1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MSB1218A-RT1 belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, low-power analog signal conditioning and discrete switching in space-constrained surface-mount designs.

FAQ

What is the maximum continuous collector current rating for MSB1218A-RT1?

The MSB1218A-RT1 has a maximum continuous collector current (I_C) rating of 100 mA at T_A = 25 °C. This rating assumes operation on a standard FR-4 PCB with the minimum recommended footprint. Derating is required above 25 °C ambient, following the published derating curve in the datasheet, where power dissipation drops linearly to zero at 150 °C ambient.

Is MSB1218A-RT1 RoHS-compliant and lead-free?

Yes, MSB1218A-RT1 is Pb-Free, halogen-free/BFR-free, and fully RoHS-compliant per EU Directive 2011/65/EU. The "G" suffix in the full orderable part number MSB1218A-RT1G explicitly denotes the lead-free version, and the device carries appropriate marking (microdot or "G") per onsemi's packaging specification BRD8011/D.

What is the pin configuration of MSB1218A-RT1 in the SC-70 package?

MSB1218A-RT1 uses Style 7 pinout for the SC-70 (SOT-323) package: Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector. This configuration is confirmed in the mechanical case outline drawing (Case 419, Style 7) and matches the internal schematic symbol orientation shown in the datasheet's marking diagram and terminal layout.

Does MSB1218A-RT1 support operation at elevated temperatures?

Yes, MSB1218A-RT1 is rated for junction temperatures up to 150 °C and storage temperatures from −55 °C to +150 °C. Its electrical characteristics-including h_FE and V_CE(sat)-are characterized at 25 °C, but the device remains functional across its full temperature range, with performance shifts documented in Figures 3 and 4 of the datasheet (e.g., h_FE variation with temperature and collector current).

How does the h_FE range of MSB1218A-RT1 compare to typical PNP transistors in the same package?

MSB1218A-RT1 specifies h_FE = 210–340 at V_CE = 10 V and I_C = 2.0 mA, which is notably higher than many SC-70 PNP transistors (e.g., MMBT3906LT1G: 100–300). This wider and higher minimum h_FE improves gain predictability in low-current amplifier designs and reduces sensitivity to base drive variations in production environments.

MSB1218A-RT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: SC-70, SOT-323

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 10mA, 100mA

Current - Collector Cutoff (Max):: 100µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 210 @ 2mA, 10V

Power - Max:: 150 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SC-70-3 (SOT323)

MSB1218A-RT1 FAQ

1.How can I place an order for MSB1218A-RT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for MSB1218A-RT1 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MSB1218A-RT1 reliable?

The price and inventory of MSB1218A-RT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MSB1218A-RT1 is usually 5 days.

3.What payment methods are accepted for MSB1218A-RT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MSB1218A-RT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MSB1218A-RT1?

MSB1218A-RT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MSB1218A-RT1 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MSB1218A-RT1?

For technical support, including MSB1218A-RT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MSB1218A-RT1 requirements.

6.How does Aetrix verify that MSB1218A-RT1 is sourced from the original manufacturer or authorized distributors?

All MSB1218A-RT1 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MSB1218A-RT1 meets industry standards.

7.What is the process for return or replacement of MSB1218A-RT1?

All MSB1218A-RT1 units undergo pre-shipment inspection (PSI). If there is an issue with MSB1218A-RT1, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MSB1218A-RT1 part is unused and in its original packaging.

Return procedure for MSB1218A-RT1:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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