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

STMicroelectronics STT818B

Name: STT818B
Brand: STMicroelectronics
SKU: STT818B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STT818B

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: SOT-23-6

Datasheet:: STT818B.pdf

Description:: TRANS PNP 30V 3A SOT-23-6L

Quantity:: RFQ Add To RFQ list

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Product details

Overview

STT818B from STMicroelectronics is a high-gain, low-voltage PNP power transistor in SOT23-6L package, rated for −3 A continuous collector current, V_CEO = −30 V, and V_CE(sat) as low as −0.075 V at I_C = −0.5 A / I_B = −5 mA. It delivers h_FE > 100 and is optimized for battery-powered switching regulators and portable equipment power management.

For engineers reviewing the STT818B datasheet, STT818B pinout, STT818B application, or STT818B equivalent, key selection criteria include saturation voltage under load, DC current gain stability across operating current, thermal resistance (R_thj-amb = 104.2 °C/W on FR4), safe operating area limits, and SOT23-6L footprint compatibility with space-constrained PCB layouts.

Technical Context

The STT818B employs Planar "Base Island" layout technology to achieve high h_FE (>100) while maintaining ultra-low V_CE(sat) down to −0.075 V. Its PNP polarity and −30 V breakdown ratings support low-side switching in negative-rail power paths.

Designed for DC and pulse-switching operation, it features specified safe operating area (SOA) curves up to 5 ms pulses, derating beyond 25°C ambient, and validated switching times under resistive loads-enabling reliable use in battery charger control stages and portable device load switches.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−30 V: Maximum collector-emitter voltage before breakdown with base open; defines safe blocking capability in low-voltage PNP switch applications.
I_C (cont.)	−3 A: Continuous collector current rating; supports sustained load switching in battery chargers and portable power rails.
V_CE(sat)	−0.075 V @ I_C = −0.5 A / I_B = −5 mA: Ultra-low saturation voltage minimizes conduction loss and self-heating in high-efficiency linear/switching regulators.
h_FE	>100 @ I_C = −0.5 A / V_CE = −1 V: High DC current gain reduces required base drive current, easing driver design and reducing base resistor power dissipation.
P_tot	1.2 W @ T_amb = 25°C: Total power dissipation limit on standard FR4 PCB; combined with R_thj-amb = 104.2 °C/W, sets practical thermal envelope.
T_J(max)	150 °C: Maximum junction temperature; enables operation in thermally demanding portable enclosures with limited airflow.

Pinout & Package

SOT23-6L is a 6-pin, surface-mount plastic package with exposed thermal pad (not electrically connected), optimized for thermal performance on FR4 PCBs. Pin numbering follows JEDEC MO-178AB standard, with pins 1–6 arranged in two rows (1–3 top, 4–6 bottom).

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Main current exit terminal; connected to higher potential rail in PNP configuration; requires low-impedance trace for return path.
2	Base	Control input; driven low relative to emitter to turn on; requires current-limiting resistor per h_FE and I_C target.
3	Collector	Main current entry terminal; tied to load or ground-referenced node; carries full switched current.
4	Emitter	Second emitter connection; internally bonded to Pin 1 to improve current sharing and thermal distribution.
5	Collector	Second collector connection; internally bonded to Pin 3 to reduce on-resistance and enhance SOA robustness.
6	Collector	Third collector connection; internal parallel bond improves thermal spreading and peak current handling (I_CM = −6 A).

Key Features

Feature	Design Value
Ultra-low V_CE(sat)	−0.075 V enables <15 mW conduction loss at 0.5 A, critical for efficiency in battery-fed systems.
High h_FE (>100)	Reduces base drive requirement to ~5 mA for 0.5 A output, simplifying bias network and lowering driver IC loading.
SOT23-6L dual-emitter/dual-collector layout	Internal paralleling of emitter and collector terminals lowers effective R_CE(sat) and improves thermal distribution across package.
ECOPACK® lead-free construction	Complies with RoHS and JEDEC JESD97; marked on package and inner box for traceable environmental compliance.

Applications

Smartphone Battery Charger Control

USB-Powered Portable Audio Amplifier

Use Scenario: Regulating charging current into Li-ion cells using linear or PWM-controlled PNP pass element.

IC Role / Device Role / Timing Role: Low-side PNP switch controlling current flow from adapter to battery; operates in active or saturated mode depending on regulation scheme.

Use Value: V_CE(sat) ≤ −0.21 V at 1.2 A ensures <250 mW dissipation, avoiding thermal shutdown in compact enclosures.

Use Scenario: Enabling/disabling power to Class AB audio amplifier stage during standby to minimize quiescent drain.

IC Role / Device Role / Timing Role: High-gain PNP load switch isolating V_CC rail; turned on/off by microcontroller GPIO.

Use Value: h_FE > 100 allows direct GPIO drive (3.3 V logic) with minimal external components, reducing BOM count.

Medical Wearable Sensor Power Sequencing

Industrial Handheld Data Logger

Use Scenario: Sequential powering of analog front-end, MCU, and RF transceiver from single Li-Po cell.

IC Role / Device Role / Timing Role: Discrete PNP power switch in multi-rail sequencing chain; controlled by supervisor IC or firmware.

Use Value: −30 V V_CEO margin accommodates transient spikes on shared battery rail without breakdown.

Use Scenario: Managing power to GPS module and SD card interface during intermittent logging cycles.

IC Role / Device Role / Timing Role: High-current PNP switch enabling 2 A peak loads during data burst transmission.

Use Value: I_CM = −6 A (5 ms) supports short GPS acquisition surges without latch-up or thermal runaway.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ON Semiconductor NSS12201MR6T1G	SOT-23-6, −2 A I_C, V_CE(sat) = −0.15 V @ −1 A, h_FE = 100–300	Lower current rating; tighter h_FE spread; optimized for logic-level drive	Preferred where base drive is constrained and 2 A suffices; less margin for surge currents.
Diodes Incorporated DMMT3906-7-F	SOT-23-6, −200 mA I_C, V_CE(sat) = −0.4 V @ −10 mA, h_FE = 100 min	Not a power-grade device; unsuitable for >500 mA loads due to thermal and SOA limits	Only viable for signal-level switching; not a functional substitute for STT818B's 3 A capability.

Compared with NSS12201MR6T1G and DMMT3906-7-F, the STT818B uniquely combines −3 A continuous rating, sub-0.1 V saturation, and SOT23-6L thermal robustness-making it the only option among the three qualified for sustained high-current battery charger switching.

Availability

STT818B is available at Aetrix Electronics and suitable for smartphone battery charger control, USB-powered portable audio amplifiers, and medical wearable sensor power sequencing requiring stable component supply and long-term industrial availability.

Supply support for STT818B 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The STT818B belongs to ST's high-performance discrete power transistor family, engineered specifically for low-voltage, high-current switching in space-constrained portable electronics where thermal efficiency and gain consistency are critical.

FAQ

Is the STT818B pin-compatible with standard SOT-23-6 transistors?

No. While physically packaged in SOT23-6L, the STT818B uses a proprietary internal pin mapping with dual emitter (Pins 1 & 4) and triple collector (Pins 3, 5 & 6) connections. Standard SOT-23-6 transistors typically follow single-emitter/single-collector/single-base layouts; direct substitution without schematic and layout review will cause functional failure.

What is the maximum allowable base current for continuous operation?

The absolute maximum continuous base current (I_B) is −0.2 A per datasheet Table 2. However, typical operating base current ranges from −5 mA to −20 mA depending on collector load. Exceeding −0.2 A risks metallization damage and permanent h_FE degradation, even if instantaneous power remains within P_tot.

Does the STT818B require a heatsink in standard FR4 PCB layout?

No external heatsink is required for ≤1.2 W dissipation at 25°C ambient, as confirmed by R_thj-amb = 104.2 °C/W on 25 mm × 25 mm FR4. At full 1.2 W, junction temperature rises ~125°C above ambient-well within the 150°C T_J(max) limit. Larger copper pours improve margin but are not mandatory.

Can the STT818B be used in avalanche mode?

No. The STT818B is not rated or characterized for avalanche energy absorption. Its safe operating area (SOA) curves in the datasheet assume forward-biased operation only. Applying reverse-biased V_CE beyond −30 V-even briefly-may cause irreversible junction breakdown and parametric shift.

STT818B Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SOT-23-6

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 30 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 20mA, 2A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 500mA, 1V

Power - Max:: 1.2 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-6L

STT818B FAQ

1.How can I place an order for STT818B through Aetrix?

Please submit a Request for Quotation (RFQ) for STT818B 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 STT818B reliable?

The price and inventory of STT818B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STT818B is usually 5 days.

3.What payment methods are accepted for STT818B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STT818B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STT818B?

STT818B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STT818B 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 STT818B?

For technical support, including STT818B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STT818B requirements.

6.How does Aetrix verify that STT818B is sourced from the original manufacturer or authorized distributors?

All STT818B 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 STT818B meets industry standards.

7.What is the process for return or replacement of STT818B?

All STT818B units undergo pre-shipment inspection (PSI). If there is an issue with STT818B, 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 STT818B part is unused and in its original packaging.

Return procedure for STT818B:

1.Submit a request within 90 days.

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

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