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onsemi BF420ZL1G
- Part No.:
- BF420ZL1G
- Manufacturer:
- onsemi
- Category:
- Single Bipolar Transistors
- Package:
- TO-226-3, TO-92-3 Long Body, Formed Leads
- Datasheet:
-
BF420ZL1G.pdf
- Description:
- TRANS NPN 300V 0.05A TO92
- Quantity:
- Payment:
- Shipping:
Inventory:7,721
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Product details
Overview
BF420ZL1G from onsemi is an NPN silicon high-voltage transistor designed for switching and amplification in off-line power supplies, CRT horizontal deflection circuits, and pulse applications. It features a 300 VCEO, 50 mA continuous collector current, 830 mW power dissipation at 25°C, 60 MHz fT, and TO-92 package with Pb-free construction.
For engineers reviewing the BF420ZL1G datasheet, pinout, applications, or equivalent options, key selection criteria include high-voltage blocking capability (300 V), low saturation voltage (≤0.5 V at IC/IB = 10), thermal resistance (RJA = 150 °C/W), and compatibility with legacy TO-92-based designs requiring RoHS-compliant sourcing.
Technical Context
The BF420ZL1G operates as a discrete NPN bipolar junction transistor optimized for high-voltage switching where fast turn-off and controlled gain are required. Its 300 VCEO and 300 VCBO ratings support use in flyback snubber networks and line-voltage interface stages, while its 60 MHz fT enables stable operation up to mid-frequency pulse applications.
Thermal performance is defined by RJA = 150 °C/W (FR4 board, 200 mm² copper) and RJL = 68 °C/W, indicating suitability for moderate-power, non-forced-air environments. The device exhibits hFE ≥ 50 at IC = 25 mA and VCE = 20 V, with VCE(sat) ≤ 0.5 V and VBE(sat) ≤ 2.0 V under specified drive conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCEO | 300 V - Supports direct connection to 230 VAC mains-derived rails with margin for transients. |
| IC (continuous) | 50 mA - Suitable for low-to-medium current switching loads such as relay drivers or small solenoids. |
| PD @ 25°C | 830 mW - Enables self-contained operation on standard FR4 PCBs without heatsinking below ~300 mW load. |
| fT | 60 MHz - Allows reliable amplification or switching up to ~10–15 MHz square-wave signals. |
| VCE(sat) | ≤ 0.5 V @ IC = 20 mA, IB = 2 mA - Minimizes conduction loss in saturated-switching topologies. |
| Cre | ≤ 1.6 pF @ VCB = 30 V - Reduces Miller effect in high-speed switching, improving turn-off consistency. |
Pinout & Package
BF420ZL1G is housed in a Pb-free TO-92 package (Case 29, Style 14), with standardized lead configuration and mechanical dimensions per ON Semiconductor specification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Emitter | Reference terminal for base-emitter junction; connects to ground or low-side return path in common-emitter configurations. |
| 2 | Collector | High-voltage output node; handles up to 300 V with controlled leakage (ICBO ≤ 10 nA). |
| 3 | Base | Current-controlled input; requires ~2 mA drive for full saturation at 20 mA collector load. |
Key Features
| Feature | Design Value |
|---|---|
| High breakdown voltage | VCEO = 300 V ensures robustness against line surges in AC/DC front-end and deflection circuits. |
| Pb-free TO-92 packaging | Complies with RoHS Directive 2011/65/EU without compromising thermal or mechanical reliability. |
| Controlled DC current gain | hFE ≥ 50 at 25 mA supports predictable base drive sizing in linear and switching modes. |
| Low feedback capacitance | Cre ≤ 1.6 pF limits unwanted coupling between collector and base during fast transitions. |
Applications
| Switch-Mode Power Supply Snubber | CRT Horizontal Deflection |
|---|---|
Use Scenario: Absorbs energy from transformer leakage inductance during MOSFET/FET turn-off in flyback converters. IC Role / Device Role / Timing Role: Discrete high-voltage clamp transistor operating in avalanche or active clamping mode. Use Value: Prevents voltage overshoot beyond 300 V using intrinsic breakdown margin and low Cre for minimal ringing. | Use Scenario: Drives horizontal output transformer primary in analog television and monitor deflection systems. IC Role / Device Role / Timing Role: High-voltage, medium-speed switch synchronized to horizontal sync pulses (~15.7 kHz). Use Value: Delivers precise timing edge control with VCE(sat) ≤ 0.5 V and fT = 60 MHz ensuring clean flyback pulse generation. |
| Industrial Relay Driver | Pulse Generator Output Stage |
Use Scenario: Interfaces microcontroller GPIO to 24–48 VDC industrial relay coils with isolation and transient suppression. IC Role / Device Role / Timing Role: Low-side NPN switch providing galvanic separation and current gain for logic-level control. Use Value: Handles 50 mA continuous coil current with guaranteed hFE ≥ 50, enabling compact base resistor design. | Use Scenario: Amplifies TTL/CMOS logic pulses into higher-current, higher-voltage waveforms for test equipment or laser diode triggering. IC Role / Device Role / Timing Role: Fast-switching emitter-follower or common-emitter buffer stage. Use Value: Maintains signal integrity up to 10 MHz due to 60 MHz fT and sub-2 VBE(sat), minimizing pulse distortion. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage NPN transistor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BF422ZL1G | VCEO = 250 V (50 V lower); otherwise identical pinout, package, and gain specs. | Suitable only where peak circuit voltage remains ≤ 250 V; not recommended for 230 VAC-derived rails. | Select BF422ZL1G only when system voltage stress is confirmed < 250 V and cost sensitivity justifies reduced margin. |
| MPSA42 | VCEO = 300 V, but hFE min = 40 (vs. 50), RJA = 200 °C/W (vs. 150 °C/W), and no Pb-free marking assurance. | Acceptable in lower-power, non-RoHS-critical designs where thermal headroom is available. | Choose MPSA42 only if Pb-free compliance is not required and thermal derating can accommodate higher RJA. |
Compared with BF420ZL1G, BF422ZL1G trades 50 V of voltage margin for identical footprint and drive, while MPSA42 offers same VCEO but lower gain and worse thermal resistance-making BF420ZL1G optimal for RoHS-compliant, thermally constrained 300 V switching.
Availability
BF420ZL1G is available at Aetrix Electronics and suitable for switch-mode power supply snubbers, CRT deflection circuits, and industrial relay drivers requiring stable component supply and full RoHS compliance.
Supply support for BF420ZL1G 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The BF420ZL1G belongs to onsemi's high-voltage discrete transistor family, engineered specifically for reliability-critical switching in AC/DC conversion, display deflection, and pulse amplification where voltage margin and thermal stability are paramount.
FAQ
What is the maximum collector-emitter voltage rating for BF420ZL1G?
The BF420ZL1G has a maximum collector-emitter voltage rating (VCEO) of 300 Vdc, verified per onsemi's official datasheet under test condition IC = 1.0 mA and IB = 0. This rating defines the absolute upper limit before breakdown occurs and must be applied with appropriate safety margin in final designs using BF420ZL1G.
Is BF420ZL1G RoHS compliant and what does the 'G' suffix indicate?
Yes, BF420ZL1G is RoHS compliant. The 'G' suffix explicitly denotes Pb-free construction per onsemi's packaging standard, confirmed in the Ordering Information table and Marking Diagram section of the BF420/D datasheet. This ensures full compliance with EU Directive 2011/65/EU without substitution or requalification.
What is the DC current gain (hFE) of BF420ZL1G under typical operating conditions?
The BF420ZL1G guarantees a minimum DC current gain (hFE) of 50 when tested at IC = 25 mA and VCE = 20 Vdc, as specified in the Electrical Characteristics table. This value is measured at TA = 25°C and supports deterministic base resistor calculation for saturation switching applications using BF420ZL1G.
Can BF420ZL1G replace BF422ZL1G in existing designs?
BF420ZL1G can replace BF422ZL1G only if the circuit's peak collector-emitter voltage exceeds 250 V. Since BF420ZL1G offers +50 V higher VCEO (300 V vs. 250 V), it provides additional margin-but both share identical pinout, package, and thermal characteristics, making BF420ZL1G a safe upgrade where voltage stress is critical.
What is the thermal resistance from junction to ambient (RJA) for BF420ZL1G?
The thermal resistance from junction to ambient (RJA) for BF420ZL1G is 150 °C/W, measured on a standard FR4 board with 200 mm² of 1 oz copper and 5 mm lead length. This value directly determines allowable power dissipation at elevated ambient temperatures and must be used in thermal calculations for BF420ZL1G deployments.
BF420ZL1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 Long Body, Formed Leads
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Transistor Type:
- NPN
- Current - Collector (Ic) (Max):
- 50 mA
- Voltage - Collector Emitter Breakdown (Max):
- 300 V
- Vce Saturation (Max) @ Ib, Ic:
- 500mV @ 2mA, 20mA
- Current - Collector Cutoff (Max):
- 10nA (ICBO)
- DC Current Gain (hFE) (Min) @ Ic, Vce:
- 50 @ 25mA, 20V
- Power - Max:
- 830 mW
- Frequency - Transition:
- 60MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92 (TO-226)
BF420ZL1G FAQ
1.How can I place an order for BF420ZL1G through Aetrix?
Please submit a Request for Quotation (RFQ) for BF420ZL1G 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 BF420ZL1G reliable?
The price and inventory of BF420ZL1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF420ZL1G is usually 5 days.
3.What payment methods are accepted for BF420ZL1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF420ZL1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF420ZL1G?
BF420ZL1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF420ZL1G 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 BF420ZL1G?
For technical support, including BF420ZL1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF420ZL1G requirements.
6.How does Aetrix verify that BF420ZL1G is sourced from the original manufacturer or authorized distributors?
All BF420ZL1G 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 BF420ZL1G meets industry standards.
7.What is the process for return or replacement of BF420ZL1G?
All BF420ZL1G units undergo pre-shipment inspection (PSI). If there is an issue with BF420ZL1G, 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 BF420ZL1G part is unused and in its original packaging.
Return procedure for BF420ZL1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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