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onsemi NST857BF3T5G
- Part No.:
- NST857BF3T5G
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- SOT-1123
- Datasheet:
-
NST857BF3T5G.pdf
- Description:
- TRANS PNP 45V 0.1A SOT-1123
- Quantity:
- Payment:
- Shipping:
Inventory:7,999
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Product details
Overview
NST857BF3T5G from onsemi is a PNP general-purpose bipolar junction transistor in SOT-1123 package, rated for −45 V VCEO, −100 mA IC, and featuring hFE of 220–475 at IC = −10 mA. It delivers low VCE(sat) ≤ −0.3 V at IC = −10 mA / IB = −0.5 mA and is optimized for space-constrained low-power amplifier circuits.
For engineers reviewing the NST857BF3T5G datasheet, pinout, applications, or equivalent options, key selection criteria include verified PNP polarity, SOT-1123 footprint compatibility, guaranteed hFE range, thermal resistance (RJA = 360 °C/W on 500 mm² copper), and Pb-free compliance per J-STD-609.
Technical Context
This device operates as a medium-current, low-voltage PNP amplifier with fixed-emitter bias topology. Its design targets linear amplification and switching in battery-powered portable electronics where board area and thermal dissipation are constrained.
It supports continuous operation up to +150 °C junction temperature and exhibits fT = 100 MHz, Cibo = 10 pF, and NF = 10 dB at IC = −0.2 mA - confirming suitability for audio preamplifier and sensor signal conditioning stages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −45 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration |
| IC (max) | −100 mA - Continuous collector current rating defining maximum linear/saturation load drive capability |
| hFE | 220–475 - DC current gain range at IC = −10 mA / VCE = −5 V, enabling predictable biasing in amplifier designs |
| VCE(sat) | ≤ −0.3 V - Low saturation voltage at IC = −10 mA / IB = −0.5 mA, minimizing power loss in switching applications |
| fT | 100 MHz - Current-gain bandwidth product indicating usable frequency limit for small-signal amplification |
| RJA (500 mm²) | 360 °C/W - Thermal resistance from junction to ambient on 500 mm² 1 oz copper, guiding PCB thermal layout |
Pinout & Package
SOT-1123 (Case 524AA) is a 3-pin ultra-miniature surface-mount package measuring 0.80 × 0.60 × 0.37 mm with 0.35 mm pitch. It enables high-density placement in wearables, hearing aids, and compact IoT sensors.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Base | Control terminal for forward-biased PNP operation; requires negative base current relative to emitter to turn on |
| 2 | Emiter | Current source terminal in PNP configuration; connected to higher potential (e.g., VCC) in common-emitter amplifier |
| 3 | Collector | Current sink terminal; output node in amplifier stage or load connection point in switch mode |
Key Features
| Feature | Design Value |
|---|---|
| High hFE range | 220–475 ensures stable DC bias point across process/temperature variation in discrete amplifier designs |
| Low VCE(sat) | ≤ −0.3 V at IC = −10 mA reduces conduction loss and self-heating in battery-operated switches |
| Pb-free construction | Complies with J-STD-609 Class 3 marking and RoHS Directive 2011/65/EU without exemption |
| Miniature SOT-1123 | 0.80 × 0.60 mm footprint saves >60% board area vs. SOT-23, critical for sub-10 mm² wearable PCBs |
Applications
| Audio Preamp Stage | Low-Power Sensor Interface |
|---|---|
Use Scenario: Amplifying weak microphone or piezoelectric sensor signals in hearing aids and voice-controlled edge devices. IC Role / Device Role / Timing Role: PNP common-emitter small-signal amplifier providing 20–40 dB voltage gain with minimal quiescent current. Use Value: High hFE and low noise figure (NF = 10 dB) preserve SNR in sub-100 μA bias conditions. |
Use Scenario: Conditioning analog outputs from temperature, pressure, or gas sensors in portable medical monitors. IC Role / Device Role / Timing Role: Discrete transimpedance or level-shifting stage converting sensor current/voltage to MCU-compatible levels. Use Value: Guaranteed VCEO = −45 V and low VCE(sat) ensure reliable operation across supply rails from 1.8 V to 5 V. |
| Portable LED Driver | Power Rail Switch |
Use Scenario: Driving low-current indicator LEDs in battery-powered instrumentation and handheld testers. IC Role / Device Role / Timing Role: PNP current-source switch controlling LED anode connection to regulated rail. Use Value: VCE(sat) ≤ −0.3 V minimizes dropout and extends battery life in 3.3 V/5 V systems. |
Use Scenario: Enabling/disabling auxiliary power domains (e.g., RF module, display backlight) in ultra-compact IoT nodes. IC Role / Device Role / Timing Role: Low-side or high-side load switch using emitter-follower or common-emitter configuration. Use Value: SOT-1123 footprint allows integration into tight BOMs where space prohibits larger packages like SOT-23. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PNP general-purpose transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBT4403LT1G | Same SOT-23 package; lower hFE (100–300), higher RJA (400 °C/W on 100 mm²), VCEO = −40 V | Less suitable for low-noise preamp stages due to wider hFE tolerance and higher thermal resistance | Select when SOT-23 assembly infrastructure exists and tighter hFE control is not required |
| DXT3906-7-F | SOT-523 package (smaller than SOT-1123); hFE = 100–300; VCEO = −40 V; RJA = 450 °C/W | Higher thermal resistance limits continuous current in thermally constrained layouts | Prefer only when absolute minimum footprint (<0.6 × 0.3 mm) outweighs thermal and gain trade-offs |
Compared with MMBT4403LT1G and DXT3906-7-F, the NST857BF3T5G offers superior hFE consistency, lower saturation voltage, and better thermal performance on standard PCB copper - making it optimal for precision low-power amplification where gain stability and efficiency are prioritized over minimal package size.
Availability
NST857BF3T5G is available at Aetrix Electronics and suitable for audio preamplifiers, portable sensor interfaces, and compact LED drivers requiring stable component supply, consistent parametric performance, and RoHS-compliant sourcing.
Supply support for NST857BF3T5G 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 focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.
The NST857BF3T5G belongs to onsemi's general-purpose bipolar transistor family designed specifically for miniaturized, low-power analog signal conditioning and switching in space- and power-constrained portable electronics.
FAQ
What is the pin configuration of the NST857BF3T5G?
The NST857BF3T5G uses SOT-1123 package with Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This configuration is confirmed in the official onsemi datasheet (Publication Order Number NST857BF3/D, Rev. 2, December 2024) and matches the mechanical outline CASE 524AA Style 1 marking diagram. No alternate pinouts are specified for this part number.
Is the NST857BF3T5G RoHS compliant and lead-free?
Yes, the NST857BF3T5G is Pb-free and RoHS compliant per EU Directive 2011/65/EU. The "G" suffix in the part number explicitly denotes lead-free packaging, and the datasheet states "This is a Pb−Free Device" under Features. It meets J-STD-609 Class 3 marking requirements with no exemptions applied.
What is the maximum operating junction temperature for the NST857BF3T5G?
The NST857BF3T5G has a specified junction and storage temperature range of −55 °C to +150 °C. This maximum operating junction temperature of +150 °C is validated under thermal test condition Note 2 (500 mm² copper), enabling reliable use in sealed enclosures or high-ambient environments such as automotive cabin modules or industrial sensors.
Does the NST857BF3T5G support high-frequency signal amplification?
The NST857BF3T5G has a current-gain bandwidth product (fT) of 100 MHz at IC = −10 mA and VCE = −5 V, confirming usability in RF front-end stages up to ~10–20 MHz and audio band amplification (20 Hz–20 kHz) with ample gain margin. It is not intended for GHz-range applications.
How does the thermal performance of NST857BF3T5G compare between different PCB layouts?
The NST857BF3T5G specifies two thermal resistance values: RJA = 432 °C/W on 100 mm² copper (Note 1) and RJA = 360 °C/W on 500 mm² copper (Note 2). This 17% improvement demonstrates measurable thermal benefit from increased copper area - critical for sustaining −100 mA IC in compact PCBs where the NST857BF3T5G is typically deployed.
NST857BF3T5G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- SOT-1123
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 100 mA
- Voltage - Collector Emitter Breakdown (Max):
- 45 V
- Vce Saturation (Max) @ Ib, Ic:
- 700mV @ 5mA, 100mA
- Current - Collector Cutoff (Max):
- 15nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 220 @ 2mA, 5V
- Power - Max:
- 290 mW
- Frequency - Transition:
- 100MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-1123
NST857BF3T5G FAQ
1.How can I place an order for NST857BF3T5G through Aetrix?
Please submit a Request for Quotation (RFQ) for NST857BF3T5G 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 NST857BF3T5G reliable?
The price and inventory of NST857BF3T5G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NST857BF3T5G is usually 5 days.
3.What payment methods are accepted for NST857BF3T5G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NST857BF3T5G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for NST857BF3T5G?
NST857BF3T5G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your NST857BF3T5G 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 NST857BF3T5G?
For technical support, including NST857BF3T5G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NST857BF3T5G requirements.
6.How does Aetrix verify that NST857BF3T5G is sourced from the original manufacturer or authorized distributors?
All NST857BF3T5G 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 NST857BF3T5G meets industry standards.
7.What is the process for return or replacement of NST857BF3T5G?
All NST857BF3T5G units undergo pre-shipment inspection (PSI). If there is an issue with NST857BF3T5G, 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 NST857BF3T5G part is unused and in its original packaging.
Return procedure for NST857BF3T5G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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