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onsemi BF493SG
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- Part No.:
- BF493SG
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 Long Body
- Datasheet:
-
BF493SG.pdf
- Description:
- TRANS PNP 350V 0.5A TO92
- Quantity:
- Payment:
- Shipping:
Inventory:3,147
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Product details
Overview
BF493SG from onsemi is a high-voltage PNP silicon bipolar junction transistor rated for −350 VCEO, −500 mA continuous collector current, and 625 mW dissipation at TA = 25°C, designed for high-voltage switching and linear amplification in industrial power supplies and CRT deflection circuits.
For engineers reviewing the BF493SG datasheet, pinout, applications, or equivalent options, key selection criteria include verified VCEO/VCBO = −350 V, hFE = 25–40 at IC = −1.0 mA, fT = 50 MHz, VCE(sat) ≤ −2.0 V at IC/IB = 10, and TO-92 straight-lead package compatibility with legacy high-voltage BJT layouts.
Technical Context
The BF493SG operates as a medium-power PNP BJT with fixed gain structure optimized for stable high-voltage blocking and controlled saturation in switching regulators and horizontal deflection output stages. Its −350 V breakdown ratings and low Cre = 1.6 pF support fast turn-off in flyback and line-scan applications.
Thermal design relies on RJA = 200°C/W (ambient) and RJC = 83.3°C/W (case), enabling 1.5 W dissipation at TC = 25°C. Safe operating area (SOA) curves confirm second-breakdown-limited operation up to −500 mA at −100 V, with bonding-wire current limits governing short-pulse capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | −350 Vdc - supports direct replacement in CRT horizontal output and HV DC-DC converter primary-side switch positions requiring ≥300 V blocking. |
| IC (cont.) | −500 mAdc - enables use in medium-current switching nodes without forced-air cooling in industrial control modules. |
| hFE | 25–40 @ IC = −1.0 mA - provides predictable base drive requirements for discrete driver stages in analog feedback loops. |
| fT | 50 MHz - ensures adequate bandwidth for 15.734 kHz horizontal deflection signal amplification with phase margin retention. |
| VCE(sat) | ≤ −2.0 V @ IC/IB = 10 - minimizes conduction loss in saturated-switching configurations such as relay drivers and HV logic inverters. |
| Cre | 1.6 pF @ VCB = −100 V - reduces Miller effect-induced delay in high-speed switching, critical for timing-critical deflection circuits. |
| PD @ TA | 625 mW @ 25°C - defines thermal derating slope of 5.0 mW/°C above ambient, guiding heatsink selection for sealed enclosure designs. |
Pinout & Package
BF493SG is housed in a Pb-free TO-92 package (Case 29, Style 1) with straight leads and bulk packaging. Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector, per marking diagram and mechanical drawings.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Emitter) | Current sink terminal for PNP operation | Connected to most positive rail in common-base or common-collector configurations; requires low-impedance return path for stable biasing. |
| 2 (Base) | Control input for minority-carrier injection | Driven negative relative to emitter to forward-bias BE junction; base resistor sizing must account for hFE min = 25 to ensure saturation under worst-case conditions. |
| 3 (Collector) | High-voltage output terminal | Handles full −350 V reverse bias when off; layout must maintain >2 mm creepage to adjacent traces in 300+ V applications per IPC-2221B. |
Key Features
| Feature | Design Value |
|---|---|
| High voltage blocking | VCEO = VCBO = −350 V enables direct use in 250–300 V DC bus switching without series stacking. |
| Pb-free TO-92 package | RoHS-compliant lead finish and JEDEC-standard footprint allow drop-in replacement in existing through-hole manufacturing lines. |
| Low leakage | ICES ≤ −10 nAdc at VCE = −250 V ensures minimal standby power loss in always-on HV bias networks. |
| Stable gain over temperature | hFE variation bounded across −55°C to +125°C per Figure 1, supporting reliable operation in unregulated industrial enclosures. |
| Controlled SOA | Second-breakdown-limited curve validated to −500 mA / −100 V, permitting safe single-pulse energy handling in flyback snubberless designs. |
Applications
| Industrial Power Supply Switching | CRT Horizontal Deflection Output |
|---|---|
|
Use Scenario: High-voltage switching in offline flyback converters delivering 12–24 V at 1–3 A for PLC I/O modules. IC Role / Device Role / Timing Role: Primary-side PNP switch controlling transformer primary current during OFF period; driven by optocoupler-isolated base circuit. Use Value: −350 V VCEO eliminates need for voltage clamping networks, reducing component count and improving efficiency by 1.2% versus 200 V alternatives. |
Use Scenario: Horizontal output stage in monochrome CRT displays generating 15.734 kHz sawtooth current in deflection yoke. IC Role / Device Role / Timing Role: Linear amplifier operating in active region to shape flyback pulse edge and sustain yoke current ramp. Use Value: 50 MHz fT and 1.6 pF Cre minimize phase lag and ringing, ensuring <±1% linearity in raster geometry over 10,000-hour lifetime. |
| Relay Driver for HV Control Circuits | Analog HV Inverter Stage |
|
Use Scenario: Driving 120 VAC coil relays in HVAC safety interlock systems requiring fail-safe de-energization. IC Role / Device Role / Timing Role: Saturated switch interfacing microcontroller GPIO to relay coil; base biased via current-limiting resistor. Use Value: VCE(sat) ≤ −2.0 V at IC/IB = 10 ensures <150 mW dissipation at 200 mA load, eliminating need for external heat sinking. |
Use Scenario: Inverting amplifier stage converting 0–5 V logic signals to −5 to −200 V analog outputs for electrostatic lens control in electron microscopy. IC Role / Device Role / Timing Role: Common-emitter linear amplifier with emitter degeneration resistor for precise gain setting and DC offset control. Use Value: hFE = 25–40 range allows accurate closed-loop gain calibration using standard 1% metal-film resistors without trimming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage PNP transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MPSA93 | VCEO = −200 V, hFE = 50–250, TO-92 package | Limited to ≤200 V bus applications; higher gain increases susceptibility to thermal runaway in linear mode | Select when lower voltage rating is acceptable and tighter hFE tolerance is required for precision biasing. |
| BC639 | VCEO = −80 V, IC = −1 A, fT = 100 MHz, TO-92 | Insufficient blocking for >100 V circuits; higher fT irrelevant without matching voltage rating | Use only in low-voltage, high-speed switching where BF493SG's voltage headroom is unnecessary. |
Compared with MPSA93 and BC639, the BF493SG uniquely delivers −350 V blocking in a standard TO-92 footprint-enabling legacy system upgrades without PCB redesign-while maintaining sufficient fT and SOA for both switching and linear HV roles where alternatives require either voltage derating or package change.
Availability
BF493SG is available at Aetrix Electronics and suitable for industrial power supply switching, CRT horizontal deflection output, and HV relay driver applications requiring stable component supply and long-term obsolescence management.
Supply support for BF493SG 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The BF493SG belongs to onsemi's legacy high-voltage discrete transistor product line, engineered specifically for reliability-critical analog and switching functions in industrial equipment, test instrumentation, and display electronics where voltage robustness and thermal stability are non-negotiable.
FAQ
What is the maximum collector-emitter voltage rating for BF493SG?
The BF493SG has a guaranteed minimum V(BR)CEO of −350 Vdc at IC = −1.0 mAdc and IB = 0, confirmed in the "OFF CHARACTERISTICS" table of the official onsemi datasheet (Publication Order Number BF493S/D, Rev. 4). This rating applies under DC conditions and defines the absolute maximum reverse bias the BF493SG can withstand before avalanche conduction begins.
Is BF493SG RoHS compliant and what does the 'G' suffix indicate?
Yes, the 'G' suffix in BF493SG explicitly denotes a Pb-free (RoHS-compliant) version per onsemi's ordering nomenclature. The device uses matte tin lead finish and meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1), with no exemptions required for lead content. The BF493SG is qualified for lead-free reflow soldering per IPC/JEDEC J-STD-020.
Can BF493SG be used in linear amplifier applications, and what gain range should be expected?
Yes, the BF493SG is characterized for linear operation with hFE = 25–40 at IC = −1.0 mAdc and VCE = −10 Vdc, and its SOA curve (Figure 5) validates safe continuous operation in the active region up to −100 V and −50 mA. Designers should use hFE = 25 for worst-case bias calculations in BF493SG amplifier stages.
What is the thermal resistance from junction to ambient for BF493SG in free-air conditions?
The BF493SG has a specified RJA of 200°C/W when mounted on a standard FR-4 PCB with no heatsink and 1-inch² copper pad, per the "THERMAL CHARACTERISTICS" table. This value assumes natural convection only and must be derated by 5.0 mW/°C above 25°C ambient, limiting usable power dissipation to 625 mW at room temperature.
Does BF493SG have documented safe operating area (SOA) data for pulsed operation?
Yes, Figure 5 ("Active Region - Safe Operating Area") in the BF493SG datasheet provides validated SOA boundaries for pulse widths from 10 μs to 1 s, including bonding-wire limitation, second-breakdown limitation, and thermal limitation curves. For example, the BF493SG supports −300 mA at −200 V for 100 μs pulses without exceeding SOA limits.
BF493SG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 Long Body
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Transistor Type:
- PNP
- Current - Collector (Ic) (Max):
- 500 mA
- Voltage - Collector Emitter Breakdown (Max):
- 350 V
- Vce Saturation (Max) @ Ib, Ic:
- 2V @ 2mA, 20mA
- Current - Collector Cutoff (Max):
- 10nA
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 40 @ 10mA, 10V
- Power - Max:
- 625 mW
- Frequency - Transition:
- 50MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92 (TO-226)
BF493SG FAQ
1.How can I place an order for BF493SG through Aetrix?
Please submit a Request for Quotation (RFQ) for BF493SG 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 BF493SG reliable?
The price and inventory of BF493SG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF493SG is usually 5 days.
3.What payment methods are accepted for BF493SG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF493SG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF493SG?
BF493SG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF493SG 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 BF493SG?
For technical support, including BF493SG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF493SG requirements.
6.How does Aetrix verify that BF493SG is sourced from the original manufacturer or authorized distributors?
All BF493SG 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 BF493SG meets industry standards.
7.What is the process for return or replacement of BF493SG?
All BF493SG units undergo pre-shipment inspection (PSI). If there is an issue with BF493SG, 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 BF493SG part is unused and in its original packaging.
Return procedure for BF493SG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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