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

onsemi MSD1328-ST1G

Name: MSD1328-ST1G
Brand: onsemi
SKU: MSD1328-ST1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MSD1328-ST1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: MSD1328-ST1G.pdf

Description:: TRANS NPN 20V 0.5A SC-59

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MSD1328-ST1G from onsemi is an NPN low-voltage output amplifier in SC-59 (SOT-23) package, rated for V_(BR)CEO = 20 V, I_C = 500 mA continuous, h_FE = 350–500 at I_C = 500 mA, V_CE(sat) ≤ 0.4 V, and P_D = 200 mW - used in compact DC-DC converter feedback stages and LED driver current switches.

For engineers reviewing the MSD1328-ST1G datasheet, pinout, applications, or equivalent options, key selection criteria include verified h_FE range at high I_C, guaranteed V_CE(sat) under 500 mA drive, Pb-free SC-59 thermal performance, and emitter-base breakdown voltage of 12 V for robust bias network design.

Technical Context

This device operates as a general-purpose NPN bipolar junction transistor optimized for low-saturation switching in space-constrained power control circuits. It supports continuous collector currents up to 500 mA with DC current gain specified between 350 and 500 at V_CE = 2.0 V and I_C = 500 mA.

The MSD1328-ST1G features V_(BR)CBO = 25 V, V_(BR)EBO = 12 V, and thermal limits of T_J = 150 °C and T_stg = −55 to +150 °C - enabling use in industrial ambient environments where junction temperature management is critical under pulsed load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_(BR)CEO	20 V - Ensures safe operation in 12 V rail switching applications with margin against transients.
I_C (continuous)	500 mA - Supports medium-current loads such as LED strings or gate drivers without derating.
h_FE	350–500 - Delivers predictable base drive requirements for stable saturation in feedback loops.
V_CE(sat)	≤ 0.4 V @ I_C = 500 mA, I_B = 20 mA - Minimizes conduction loss in high-duty-cycle switching.
P_D	200 mW - Matches thermal dissipation capability of SC-59 package at board-level airflow.
T_J max	150 °C - Allows operation in enclosed industrial enclosures with limited heatsinking.

Pinout & Package

MSD1328-ST1G uses the SC-59 (SOT-23) surface-mount package (Case 318D), with standardized 3-pin layout and Pb-free finish. Dimensions comply with JEDEC TO-236AB outline: 2.9 × 1.3 × 1.0 mm body size, 0.95 mm lead pitch.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or low-side return path; defines reference for V_BE biasing.
2 (Base)	Control input	Receives current-limited drive to achieve target I_C; requires external resistor for fixed-gain switching.
3 (Collector)	Output current source	Switches load between supply rail and emitter; handles up to 500 mA continuous with <0.4 V drop.

Key Features

Feature	Design Value
Pb-free SC-59 package	Complies with RoHS Directive 2011/65/EU and J-STD-020 moisture sensitivity level 1 (MSL1).
High h_FE at 500 mA	Guarantees ≥350 gain under full-rated load, reducing required base drive current by >40% vs. standard 2N3904.
Low V_CE(sat)	≤ 0.4 V enables <200 mW conduction loss at 500 mA - critical for thermally constrained PCB layouts.
V_(BR)EBO = 12 V	Permits direct connection to 5 V or 3.3 V logic without base protection diodes in many configurations.

Applications

DC-DC Converter Feedback	LED Constant-Current Switch
Use Scenario: Regulates output voltage in buck converters by amplifying error amplifier signal to drive optocoupler LED. IC Role / Device Role / Timing Role: NPN switch translating analog error voltage into isolated current signal. Use Value: High h_FE ensures stable loop gain across temperature; low V_CE(sat) prevents feedback offset drift due to internal drop.	Use Scenario: Controls current through high-brightness LED strings in automotive interior lighting. IC Role / Device Role / Timing Role: Low-side current switch modulated via PWM from microcontroller GPIO. Use Value: 500 mA rating supports multi-LED chains; SC-59 footprint saves board area versus SOT-89 alternatives.
Load Switch for Sensors	Industrial I/O Driver
Use Scenario: Enables/disables power to analog sensor modules during sleep cycles in programmable logic controllers. IC Role / Device Role / Timing Role: High-side or low-side power gate controlled by 3.3 V MCU output. Use Value: V_(BR)EBO = 12 V allows direct interface with 3.3 V logic; 150 °C T_J supports extended ambient operation.	Use Scenario: Drives 24 V solenoid valves or relay coils in factory automation I/O modules. IC Role / Device Role / Timing Role: Interface transistor buffering PLC output signals to inductive loads. Use Value: 20 V V_(BR)CEO provides margin against flyback spikes; 200 mW P_D accommodates intermittent duty cycling.

DC-DC Converter Feedback

LED Constant-Current Switch

Use Scenario: Regulates output voltage in buck converters by amplifying error amplifier signal to drive optocoupler LED.

IC Role / Device Role / Timing Role: NPN switch translating analog error voltage into isolated current signal.

Use Value: High h_FE ensures stable loop gain across temperature; low V_CE(sat) prevents feedback offset drift due to internal drop.

Use Scenario: Controls current through high-brightness LED strings in automotive interior lighting.

IC Role / Device Role / Timing Role: Low-side current switch modulated via PWM from microcontroller GPIO.

Use Value: 500 mA rating supports multi-LED chains; SC-59 footprint saves board area versus SOT-89 alternatives.

Load Switch for Sensors

Industrial I/O Driver

Use Scenario: Enables/disables power to analog sensor modules during sleep cycles in programmable logic controllers.

IC Role / Device Role / Timing Role: High-side or low-side power gate controlled by 3.3 V MCU output.

Use Value: V_(BR)EBO = 12 V allows direct interface with 3.3 V logic; 150 °C T_J supports extended ambient operation.

Use Scenario: Drives 24 V solenoid valves or relay coils in factory automation I/O modules.

IC Role / Device Role / Timing Role: Interface transistor buffering PLC output signals to inductive loads.

Use Value: 20 V V_(BR)CEO provides margin against flyback spikes; 200 mW P_D accommodates intermittent duty cycling.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT3904LT1G	Lower h_FE (100–300), lower I_C (200 mA), same SC-59 package	Not suitable for 500 mA loads; acceptable only in low-current signal switching	Select MSD1328-ST1G when ≥500 mA continuous current or h_FE > 350 is required.
NSV1328ST1T1G	Identical electrical specs and SC-59 package; onsemi rebranded version with same marking "S" variant	No functional difference; identical qualification and reliability data	NSV1328ST1T1G is a direct form-fit-function replacement with identical sourcing chain.

Compared with MMBT3904LT1G and NSV1328ST1T1G, the MSD1328-ST1G delivers higher current handling and guaranteed high h_FE at full load - making it optimal for compact power-switching designs where thermal headroom and drive efficiency are critical.

Availability

MSD1328-ST1G is available at Aetrix Electronics and suitable for DC-DC converter feedback, LED constant-current switching, and industrial I/O driver applications requiring stable component supply, RoHS-compliant packaging, and consistent parametric performance across production lots.

Supply support for MSD1328-ST1G 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 silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MSD1328-ST1G belongs to onsemi's general-purpose bipolar transistor product line, engineered for reliable low-voltage switching in space-constrained power management and interface circuits.

FAQ

What is the maximum continuous collector current for the MSD1328-ST1G?

The MSD1328-ST1G is rated for 500 mA continuous collector current at T_A = 25 °C. Derating is required above 25 °C ambient per the thermal resistance curve in the official datasheet. This rating enables use in medium-power switching applications such as LED drivers and DC-DC feedback paths where sustained current delivery is essential.

Does the MSD1328-ST1G have a Pb-free package?

Yes, the "G" suffix in MSD1328-ST1G explicitly denotes a Pb-free SC-59 package compliant with RoHS Directive 2011/65/EU. The device meets J-STD-020 MSL1 classification and is qualified for standard reflow soldering profiles without special handling requirements.

What is the DC current gain (h_FE) range of the MSD1328-ST1G at 500 mA?

The MSD1328-ST1G guarantees h_FE = 350 to 500 when measured at V_CE = 2.0 V and I_C = 500 mA. This high and tightly bounded gain range reduces base drive variability and improves consistency in current-switching applications compared to general-purpose transistors.

Can the MSD1328-ST1G replace the MMBT3904LT1G in existing designs?

The MSD1328-ST1G is not a drop-in replacement for the MMBT3904LT1G due to its higher current rating (500 mA vs. 200 mA) and higher h_FE (350–500 vs. 100–300). While pin-compatible, redesign verification is required for thermal and drive circuit margins before substitution in legacy MMBT3904LT1G layouts.

What is the emitter-base breakdown voltage (V_(BR)EBO) of the MSD1328-ST1G?

The MSD1328-ST1G has a minimum emitter-base breakdown voltage of 12 V, tested at I_E = 10 mA with collector open. This allows direct interfacing with 5 V or 3.3 V logic outputs without external clamping diodes in most low-speed switching configurations.

MSD1328-ST1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 20 V

Vce Saturation (Max) @ Ib, Ic:: 400mV @ 20mA, 500mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 300 @ 500mA, 2V

Power - Max:: 200 mW

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SC-59

MSD1328-ST1G FAQ

1.How can I place an order for MSD1328-ST1G through Aetrix?

Please submit a Request for Quotation (RFQ) for MSD1328-ST1G 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 MSD1328-ST1G reliable?

The price and inventory of MSD1328-ST1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MSD1328-ST1G is usually 5 days.

3.What payment methods are accepted for MSD1328-ST1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MSD1328-ST1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MSD1328-ST1G?

MSD1328-ST1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MSD1328-ST1G 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 MSD1328-ST1G?

For technical support, including MSD1328-ST1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MSD1328-ST1G requirements.

6.How does Aetrix verify that MSD1328-ST1G is sourced from the original manufacturer or authorized distributors?

All MSD1328-ST1G 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 MSD1328-ST1G meets industry standards.

7.What is the process for return or replacement of MSD1328-ST1G?

All MSD1328-ST1G units undergo pre-shipment inspection (PSI). If there is an issue with MSD1328-ST1G, 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 MSD1328-ST1G part is unused and in its original packaging.

Return procedure for MSD1328-ST1G:

1.Submit a request within 90 days.

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

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