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

STMicroelectronics SD1433

Name: SD1433
Brand: STMicroelectronics
SKU: SD1433
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SD1433

Manufacturer:: STMicroelectronics

Category:: Bipolar RF Transistors

Package:: M122

Datasheet:: SD1433.pdf

Description:: RF TRANS NPN 16V M122

Quantity:: RFQ Add To RFQ list

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Inventory:6,142

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Product details

Overview

SD1433 from STMicroelectronics is a Class C epitaxial silicon NPN planar RF power bipolar transistor designed for UHF mobile driver stages operating at 470 MHz, delivering ≥10 W output power with 7 dB typical gain and 60% efficiency at 12.5 V collector-emitter voltage in common-emitter configuration.

For engineers reviewing the SD1433 datasheet, SD1433 pinout, SD1433 application, or SD1433 equivalent, key selection considerations include its 36 V C-B breakdown rating, 2.5 A DC current capability, 3.0 °C/W junction-to-case thermal resistance, M122 stud-mount package, and verified performance under infinite VSWR conditions in UHF base station driver circuits.

Technical Context

The SD1433 employs emitter ballasted geometry to ensure stable power gain and ruggedness under mismatched load conditions. Its design targets fixed-frequency UHF amplification where high efficiency and VSWR tolerance are prioritized over broadband linearity.

It operates in Class C mode with fixed bias (V_CE = 12.5 V), optimized for narrowband 450–512 MHz applications. Input impedance is 1.5 – j2.7 Ω and collector load impedance is 5.7 + j1.5 Ω at 470 MHz, requiring precise matching network design.

Key Specifications

Parameter	Value and Actual Design Meaning
f_OP	470 MHz - center frequency of specified RF power performance
P_OUT	≥10 W - minimum saturated RF output power into matched load
G_P	7 dB - small-signal power gain at P_OUT = 10 W, enabling single-stage driver design
η	60% - drain efficiency at rated output, reducing heat sink requirements
V_CEO	16 V - maximum safe collector-emitter voltage under operating bias
R_TH(j-c)	3.0 °C/W - enables thermal management with standard copper-clad stud mount heatsinking
Z_IN	1.5 – j2.7 Ω @ 470 MHz - defines input matching network component values

Pinout & Package

M122 is a 4-lead stud-mount metal package with insulated collector (stud), emitter (pin 1), base (pin 2), and auxiliary emitter (pin 3); case serves as collector terminal. Epoxy-sealed construction ensures environmental robustness in mobile base stations.

Pin/Terminal	Circuit Role	Design Meaning
Stud (Case)	Collector	Electrically isolated mounting surface; primary heat path to heatsink
Pin 1	Emitter	Main emitter connection; used with external emitter ballast resistor for stability
Pin 2	Base	DC bias and RF drive input node; requires impedance-matched feed
Pin 3	Auxiliary Emitter	Second emitter terminal for improved thermal symmetry and current sharing

Key Features

Feature	Design Value
Emitter ballasted geometry	Enables stable gain and infinite VSWR tolerance without external protection circuitry
Class C operation	Optimized for high-efficiency, fixed-frequency driver use with minimal quiescent current
3.0 °C/W R_TH(j-c)	Supports 58 W continuous dissipation with moderate heatsink sizing
36 V V_CBO	Provides margin against transient voltage spikes in mobile RF power stages

Applications

Land Mobile Radio Base Station Driver

UHF Public Safety Transmitter Stage

Use Scenario: Final driver stage in 450–470 MHz land mobile radio repeater systems requiring high reliability under antenna mismatch.

IC Role / Device Role / Timing Role: Class C RF power amplifier transistor delivering 10 W output with 7 dB gain into 50 Ω load.

Use Value: 60% efficiency reduces thermal load on compact chassis-mounted heatsinks in sealed enclosures.

Use Scenario: High-reliability transmitter driver in emergency response vehicle radios operating in 470 MHz band.

IC Role / Device Role / Timing Role: Common-emitter configured NPN RF power transistor with infinite VSWR tolerance.

Use Value: Emitter ballasting prevents thermal runaway during antenna detuning or cable fault events.

UHF Industrial Remote Control Transmitter

Fixed-Frequency Wireless Data Link Amplifier

Use Scenario: Power amplifier in industrial telemetry transmitters deployed in harsh electromagnetic environments.

IC Role / Device Role / Timing Role: Narrowband 470 MHz RF driver with 16 V V_CEO and 2.5 A I_C rating.

Use Value: M122 stud-mount package enables direct bolt-down to aluminum chassis for low-inductance grounding and thermal conduction.

Use Scenario: Fixed-frequency 470 MHz data link transmitter in SCADA systems requiring consistent output power.

IC Role / Device Role / Timing Role: RF power transistor with 1.5 – j2.7 Ω input impedance for repeatable matching network design.

Use Value: Stable 10 W output across temperature supports unattended operation in remote monitoring sites.

Equivalent & Alternatives

The following parts are listed as comparable options for similar UHF RF power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MRF454	Higher P_OUT (15 W), wider bandwidth (136–512 MHz), TO-220AB package	Requires different thermal interface and PCB layout; less rugged under infinite VSWR	Preferred when broader frequency coverage or higher output is needed, but demands more complex matching
BLW60	Lower gain (5 dB), lower efficiency (50%), same M122 package, 470 MHz optimized	Used in legacy broadcast exciters; less suitable for mobile battery-constrained designs	Consider only if legacy BOM compatibility or lower cost is critical and 2 dB gain margin can be accepted

Compared with MRF454 and BLW60, the SD1433 uniquely balances 10 W output, 7 dB gain, 60% efficiency, and infinite VSWR tolerance in a stud-mount package-making it optimal for space-constrained, high-reliability UHF mobile driver applications where thermal and load mismatch resilience are non-negotiable.

Availability

SD1433 is available at Aetrix Electronics and suitable for land mobile radio base stations, public safety transmitters, and industrial wireless telemetry systems requiring stable component supply and long-term obsolescence mitigation support.

Supply support for SD1433 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in analog, power, and RF components for industrial, automotive, and communications markets.

The SD1433 belongs to ST's legacy RF power transistor product line, engineered specifically for ruggedized UHF mobile infrastructure where efficiency, thermal robustness, and load mismatch immunity are essential.

FAQ

Is SD1433 still in active production?

No-SD1433 is marked as obsolete by STMicroelectronics per official documentation. However, Aetrix Electronics maintains legacy inventory with full traceability and offers extended lifecycle support including cross-reference engineering and last-time-buy coordination for ongoing production programs.

What is the recommended biasing method for SD1433 in Class C operation?

SD1433 requires fixed DC bias: V_CE = 12.5 V, with base driven via impedance-matched network. The datasheet specifies no base current specification-bias is set by external network to achieve target P_OUT and efficiency; emitter ballasting eliminates need for active bias stabilization.

Can SD1433 be used in linear (Class A/AB) mode?

No-it is specifically optimized for Class C switching operation. Its emitter ballasted geometry, low V_CEO (16 V), and narrowband impedance characteristics make it unsuitable for linear amplification; attempting Class AB risks thermal instability and gain collapse outside 450–512 MHz.

What thermal interface material is recommended for the M122 stud mount?

A thermally conductive, electrically insulating grease (e.g., Dow Corning TC-5123) or ceramic washer (e.g., Bergquist Sil-Pad 900S) is required between the insulated stud and heatsink. Minimum mounting torque is 12–15 in-lb to ensure R_TH(j-c) ≤ 3.0 °C/W without stud deformation.

SD1433 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: M122

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Voltage - Collector Emitter Breakdown (Max):: 16V

Frequency - Transition:: -

Noise Figure (dB Typ @ f):: -

Gain:: 7dB

Power - Max:: 58W

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10 @ 1A, 5V

Current - Collector (Ic) (Max):: 2.5A

Operating Temperature:: 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Chassis, Stud Mount

Supplier Device Package:: M122

SD1433 FAQ

1.How can I place an order for SD1433 through Aetrix?

Please submit a Request for Quotation (RFQ) for SD1433 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 SD1433 reliable?

The price and inventory of SD1433 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SD1433 is usually 5 days.

3.What payment methods are accepted for SD1433?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SD1433 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SD1433?

SD1433 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SD1433 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 SD1433?

For technical support, including SD1433 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SD1433 requirements.

6.How does Aetrix verify that SD1433 is sourced from the original manufacturer or authorized distributors?

All SD1433 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 SD1433 meets industry standards.

7.What is the process for return or replacement of SD1433?

All SD1433 units undergo pre-shipment inspection (PSI). If there is an issue with SD1433, 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 SD1433 part is unused and in its original packaging.

Return procedure for SD1433:

1.Submit a request within 90 days.

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

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