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onsemi SMMBT6521LT1G
- Part No.:
- SMMBT6521LT1G
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
SMMBT6521LT1G.pdf
- Description:
- TRANS NPN 25V 0.1A SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,883
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Product details
Overview
SMMBT6521LT1G from onsemi is an NPN silicon small-signal amplifier transistor in SOT-23 package, rated for VCEO = 25 V, IC = 100 mA, and hFE = 150–600 (at IC = 2–100 mA), optimized for low-noise audio preamplification and general-purpose switching in automotive and industrial control circuits.
For engineers reviewing the SMMBT6521LT1G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating data, noise performance (NF ≤ 3.0 dB), AEC-Q101 qualification status, and validated alternative part options for design-in and supply continuity planning.
Technical Context
This device operates as a discrete NPN bipolar junction transistor with fixed-emitter bias configuration capability, supporting linear amplification up to fT ≈ 200 MHz (at IC = 1 mA, VCE = 10 V) and exhibiting low output capacitance (Cobo ≤ 3.5 pF at VCB = 10 V). Its thermal resistance RJA is 556 °C/W on FR-5 board and 417 °C/W on alumina substrate.
The SMMBT6521LT1G features AEC-Q101 qualification and PPAP capability, Pb-free/Halogen-free/RoHS-compliant construction, and specified cutoff currents (ICBO ≤ 0.5 µA, IEBO ≤ 10 nA), enabling use in automotive signal conditioning and precision sensor interface stages where reliability and low leakage are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 25 V - Maximum collector-emitter voltage before breakdown; defines safe operating range in common-emitter amplifier or switch configurations. |
| IC (max) | 100 mA - Continuous collector current limit; sets upper bound for load-driving capability in low-power active circuits. |
| hFE | 150–600 - DC current gain range across test conditions (2–100 mA); enables predictable base drive sizing for saturation or linear operation. |
| VCE(sat) | ≤ 0.5 V at IC = 50 mA, IB = 5 mA - Low saturation voltage ensures minimal power loss and heat generation in switching applications. |
| NF | ≤ 3.0 dB at IC = 10 mA, VCE = 5 V, 10 Hz–10 kHz - Confirmed low-noise performance suitable for microphone preamps and sensor front-ends. |
| Cobo | ≤ 3.5 pF at VCB = 10 V - Low output capacitance supports stable high-frequency gain and minimizes Miller effect in RF-coupled stages. |
| RJA (FR-5) | 556 °C/W - Thermal resistance determines junction temperature rise per mW dissipated; requires layout-aware copper area for thermal management. |
Pinout & Package
SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm body size, 1.90 mm lead pitch, case style 318, style 6 pin assignment.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Base | Control terminal for forward-biased junction; requires current-limited drive to achieve target hFE-based collector current. |
| 2 | Emitter | Common reference node in common-emitter configuration; connects to ground or low-impedance return path for signal integrity. |
| 3 | Collector | Output terminal carrying amplified/saturated current; routed to load or next stage with controlled trace inductance. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronics including engine control modules and body electronics requiring extended temperature and life-cycle reliability. |
| Pb-free / RoHS compliant | Meets global environmental compliance mandates without compromising solderability or long-term intermetallic stability in reflow assembly. |
| Low noise figure (NF ≤ 3.0 dB) | Enables high-fidelity analog signal amplification in battery-powered audio interfaces and precision instrumentation front-ends. |
| High hFE range (150–600) | Reduces required base drive current across production lots, easing microcontroller GPIO sourcing and improving power efficiency. |
| Low VCE(sat) (≤ 0.5 V) | Minimizes conduction loss in digital logic-level switching and low-voltage regulator pass elements, reducing thermal stress. |
Applications
| Automotive Sensor Interface | Portable Audio Preamp |
|---|---|
|
Use Scenario: Amplifying low-level signals from piezoresistive pressure sensors in brake fluid or manifold pressure modules. IC Role / Device Role / Timing Role: Discrete NPN amplifier in common-emitter configuration with emitter degeneration for DC stability and gain linearity. Use Value: Confirmed NF ≤ 3.0 dB and hFE ≥ 150 at IC = 2 mA ensure SNR preservation and consistent gain across temperature (−40°C to +125°C). |
Use Scenario: First-stage gain block for electret microphone signals in Bluetooth headsets and voice-controlled IoT devices. IC Role / Device Role / Timing Role: Low-noise, low-current amplifier biased at IC = 1 mA to match MEMS mic output impedance and minimize battery drain. Use Value: Cobo ≤ 3.5 pF and fT ≈ 200 MHz support wideband audio fidelity without peaking or instability in RC-coupled stages. |
| Industrial PLC Input Conditioning | LED Driver Switch |
|
Use Scenario: Level-shifting and current amplification of 4–20 mA loop signals into ADC input ranges within programmable logic controllers. IC Role / Device Role / Timing Role: Linear-mode transistor with VCEO = 25 V and IC = 100 mA handling full-scale loop current with minimal self-heating. Use Value: VCE(sat) ≤ 0.5 V at IC = 20 mA ensures <10 mW dissipation, eliminating need for heatsinking in dense I/O modules. |
Use Scenario: Driving indicator LEDs or low-current status lamps from MCU GPIO pins in medical and test equipment panels. IC Role / Device Role / Timing Role: Digital switch in common-emitter configuration with base resistor selected for IB/IC = 10 to guarantee saturation. Use Value: hFE ≥ 600 at IC = 2 mA allows sub-100 µA GPIO sourcing, compatible with ultra-low-power microcontrollers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar NPN small-signal amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBT6521LT1G | Same die, non-automotive grade; no S-prefix; AEC-Q101 not claimed | Lacks PPAP documentation and automotive change control; suitable for commercial/industrial only | Select when automotive qualification is unnecessary and cost sensitivity is higher |
| BC846B,215 | hFE = 200–450 (IC = 10 mA); VCEO = 65 V; NF = 4.5 dB; SOT-23, same pinout | Higher voltage rating but higher noise; less optimal for low-level audio | Prefer for general-purpose switching where VCEO > 25 V is required and noise is secondary |
Compared with MMBT6521LT1G and BC846B,215, the SMMBT6521LT1G uniquely combines AEC-Q101 compliance, sub-3 dB noise, and tight hFE distribution-making it the only choice for automotive-grade low-noise amplification where both reliability and signal fidelity are mandatory.
Availability
SMMBT6521LT1G is available at Aetrix Electronics and suitable for automotive sensor interfaces, portable audio preamplifiers, industrial PLC input conditioning, and LED driver switching requiring stable component supply across production lifecycles.
Supply support for SMMBT6521LT1G 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 specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The SMMBT6521LT1G belongs to onsemi's automotive-qualified discrete transistor portfolio, designed specifically for signal amplification and switching in harsh-environment electronic control units where AEC-Q101 reliability and low-noise performance are essential.
FAQ
What is the maximum continuous collector current rating for the SMMBT6521LT1G?
The SMMBT6521LT1G has a maximum continuous collector current (IC) rating of 100 mA at TA = 25 °C. Derating applies above 25 °C per the thermal characteristics table: 1.8 mW/°C on FR-5 board and 2.4 mW/°C on alumina substrate. This rating assumes proper PCB copper area and ambient airflow to maintain junction temperature below 150 °C.
Is the SMMBT6521LT1G pin-compatible with the MMBT6521LT1G?
Yes, the SMMBT6521LT1G shares identical SOT-23 package dimensions, pinout (Style 6: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector), and electrical specifications with the MMBT6521LT1G. The "S" prefix denotes automotive qualification (AEC-Q101, PPAP-capable) and unique site/control change requirements, but mechanical and electrical interoperability is maintained.
What is the noise figure specification for the SMMBT6521LT1G and under what conditions is it measured?
The SMMBT6521LT1G has a maximum noise figure (NF) of 3.0 dB, measured at IC = 10 mA, VCE = 5.0 V, with a power bandwidth of 15.7 kHz (3.0 dB points at 10 Hz and 10 kHz). This value reflects its suitability for low-noise preamplifier stages in audio and sensor signal chains where signal integrity is critical.
Does the SMMBT6521LT1G meet automotive reliability standards?
Yes, the SMMBT6521LT1G is AEC-Q101 qualified and PPAP capable. It undergoes stress testing for temperature cycling, humidity bias, HTRB, and ESD per AEC-Q101 Rev D, confirming suitability for automotive applications including engine control, body electronics, and ADAS sensor interfaces operating from −40 °C to +150 °C junction temperature.
What is the thermal resistance (RJA) of the SMMBT6521LT1G on standard FR-5 PCB?
The SMMBT6521LT1G has a thermal resistance RJA of 556 °C/W when mounted on an FR-5 board (1.0 × 0.75 × 0.062 in.) at TA = 25 °C. This value assumes no additional copper pour; adding 1-inch² of 2-oz copper on the collector pad reduces RJA significantly-designers should consult onsemi's AN569 for transient thermal modeling guidance specific to the SMMBT6521LT1G.
SMMBT6521LT1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 100 mA
- Voltage - Collector Emitter Breakdown (Max):
- 25 V
- Vce Saturation (Max) @ Ib, Ic:
- 500mV @ 5mA, 50mA
- Current - Collector Cutoff (Max):
- 500nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 300 @ 2mA, 10V
- Power - Max:
- 225 mW
- Frequency - Transition:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3 (TO-236)
SMMBT6521LT1G FAQ
1.How can I place an order for SMMBT6521LT1G through Aetrix?
Please submit a Request for Quotation (RFQ) for SMMBT6521LT1G 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 SMMBT6521LT1G reliable?
The price and inventory of SMMBT6521LT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMMBT6521LT1G is usually 5 days.
3.What payment methods are accepted for SMMBT6521LT1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMMBT6521LT1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMMBT6521LT1G?
SMMBT6521LT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMMBT6521LT1G 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 SMMBT6521LT1G?
For technical support, including SMMBT6521LT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMMBT6521LT1G requirements.
6.How does Aetrix verify that SMMBT6521LT1G is sourced from the original manufacturer or authorized distributors?
All SMMBT6521LT1G 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 SMMBT6521LT1G meets industry standards.
7.What is the process for return or replacement of SMMBT6521LT1G?
All SMMBT6521LT1G units undergo pre-shipment inspection (PSI). If there is an issue with SMMBT6521LT1G, 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 SMMBT6521LT1G part is unused and in its original packaging.
Return procedure for SMMBT6521LT1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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