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Nexperia USA Inc. BAS521-QF
- Part No.:
- BAS521-QF
- Manufacturer:
- Nexperia USA Inc.
- Category:
- Single Diodes
- Package:
- SC-79, SOD-523
- Datasheet:
-
BAS521-QF.pdf
- Description:
- BAS521-Q/SOD523/TO-236AB
- Quantity:
- Payment:
- Shipping:
Inventory:8,825
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Product details
Overview
BAS521-QF from Nexperia is a high-voltage switching diode in SOD523 (SC-79) package, rated for 300 V repetitive peak reverse voltage, 1 A repetitive peak forward current, and 16–50 ns reverse recovery time. It serves as a fast, automotive-qualified unidirectional switch in flyback snubbers, ESD protection paths, and high-side clamp circuits.
For engineers reviewing the BAS521-QF datasheet, BAS521-QF pinout, BAS521-QF application, or BAS521-QF equivalent, this page delivers verified electrical parameters, AEC-Q101 qualification status, thermal resistance values, junction-to-solder-point characterization, and real-world use context for high-voltage transient suppression and signal routing.
Technical Context
This diode employs a planar epitaxial silicon structure optimized for low capacitance (0.4–5 pF at 0 V) and fast minority-carrier recombination to achieve trr ≤ 50 ns under defined test conditions (IF = 30 mA, IR = 30 mA, RL = 100 Ω). Its 300 V VRRM rating enables operation in 24 V and 48 V automotive power rails with margin against load-dump transients.
The device is qualified per AEC-Q101 with full temperature range operation (−65 °C to +150 °C), uses reflow-only soldering, and features a cathode-tab thermal path yielding Rth(j–sp) = 120 K/W - critical for pulsed-current reliability in DC–DC converter freewheeling paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRRM | 300 V - supports 24/48 V automotive systems with ≥2× margin over ISO 7637-2 pulse 5a (120 V) and pulse 5b (200 V) |
| trr | 16–50 ns - enables switching frequencies up to ~10 MHz in snubberless flyback and active clamp topologies |
| IFRM | 1 A - sustains repetitive 1 ms pulses at 25% duty cycle for relay driver and solenoid interface applications |
| VF @ 100 mA | 0.95–1.1 V - limits conduction loss to <110 mW at 100 mA, reducing thermal stress in space-constrained layouts |
| Cd @ 0 V | 0.4–5 pF - minimizes capacitive loading on high-speed logic lines and RF antenna switches |
| Rth(j–sp) | 120 K/W - allows direct thermal coupling to PCB copper pour via cathode tab, improving pulsed-power handling |
Pinout & Package
Encapsulated in ultra-small SOD523 (SC-79) plastic SMD package: 1.2 mm × 0.8 mm × 0.6 mm body, flat lead configuration with exposed cathode tab for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (K) | Cathode | Primary current exit terminal; thermally connected to exposed metal tab for junction-to-PCB heat transfer |
| 2 (A) | Anode | Current entry terminal; electrically isolated from tab; used for forward-bias connection in clamping and rectification |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood environments including temperature cycling, HAST, and mechanical shock per discrete semiconductor standard |
| Ultra-small SOD523 footprint | Reduces board area by >60% vs. SOD-123; enables placement adjacent to IC pins without trace stubs |
| Low reverse leakage | IR ≤ 150 nA @ 250 V, 25 °C - ensures minimal standby current in always-on battery monitoring circuits |
| High IFSM surge rating | 4.5 A non-repetitive peak - withstands inrush currents during hot-plug events in infotainment power supplies |
Applications
| Automotive Load-Dump Protection | High-Speed Logic-Level Clamping |
|---|---|
Use Scenario: Suppresses ISO 7637-2 Pulse 5a (120 V, 100 ms) and Pulse 5b (200 V, 400 ms) transients on 12 V/24 V vehicle power nets. IC Role / Device Role / Timing Role: Unidirectional clamping diode placed between rail and ground, conducting only during overvoltage events. Use Value: 300 V VRRM provides 50% headroom above worst-case load dump; 16 ns trr ensures rapid turn-on before downstream regulator damage. | Use Scenario: Protects GPIO pins of microcontrollers and FPGAs from ESD and overshoot during hot-swap or cable disconnect events. IC Role / Device Role / Timing Role: Low-capacitance (≤5 pF) shunt diode tied between I/O line and VCC/GND to clamp fast edges. Use Value: Sub-5 pF Cd avoids signal integrity degradation on 100+ MHz digital lines; AEC-Q101 grade ensures reliability in telematics modules. |
| DC–DC Converter Freewheeling | Industrial Relay Driver Snubber |
Use Scenario: Provides freewheeling path for inductive energy in 500 kHz–2 MHz buck/boost converters powering ADAS sensors. IC Role / Device Role / Timing Role: Fast-recovery diode in synchronous rectifier or catch configuration, conducting during low-side switch off-time. Use Value: 50 ns max trr limits reverse recovery charge (Qrr), reducing switching losses and EMI generation at high frequency. | Use Scenario: Absorbs inductive kickback from 24 V DC industrial relays (e.g., PLC output stages) to prevent MOSFET drain overvoltage. IC Role / Device Role / Timing Role: High-voltage clamp diode across relay coil, conducting only during de-energization transient. Use Value: 300 V rating exceeds relay coil flyback spikes (>200 V typical); 1 A IFRM handles repeated 100 ms coil discharge pulses. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage switching diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ON Semiconductor NSR0230P2T5G | Lower VRRM (30 V), higher VF (1.2 V), same SOD-523 package | Not suitable for >48 V systems; limited to low-voltage logic clamping | Select only when VRRM ≤ 30 V suffices and lower cost is prioritized over voltage margin |
| Vishay VS-2EDH03-M3/84A | Higher VRRM (300 V), TO-236AB (SOT-23) package, larger footprint, VF = 1.05 V | Compatible voltage rating but lacks AEC-Q101 qualification and has 3× larger board area | Choose if legacy SOT-23 layout exists and automotive qualification is not required |
Compared with NSR0230P2T5G and VS-2EDH03-M3/84A, BAS521-QF uniquely combines AEC-Q101 qualification, 300 V rating, SOD523 size, and sub-50 ns trr - making it the only option for space-constrained, high-reliability automotive switching where voltage margin and speed are jointly critical.
Availability
BAS521-QF is available at Aetrix Electronics and suitable for automotive power management, industrial relay interfaces, high-speed logic protection, and DC–DC converter freewheeling requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for BAS521-QF 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
Nexperia is a global semiconductor expert focused on essential efficiency, delivering high-performance, reliable discrete, logic, and MOSFET devices for automotive, industrial, and consumer markets.
The BAS521-QF belongs to Nexperia's AEC-Q101-qualified high-voltage switching diode product line, engineered specifically for robust transient suppression and fast switching in harsh automotive and industrial power systems.
FAQ
Is BAS521-QF suitable for reflow soldering only?
Yes. The datasheet explicitly states reflow soldering is the only recommended method. Wave or hand soldering risks exceeding the 90 °C solder point temperature limit at the cathode tab and may compromise thermal performance or cause delamination. Reflow profile must comply with JEDEC J-STD-020 for MSL1 devices.
What is the maximum continuous forward current for BAS521-QF?
The maximum continuous forward current is 250 mA, defined at solder point temperature Tsp ≤ 90 °C. This rating assumes proper PCB thermal design - specifically, mounting on FR4 with single-sided copper and standard SOD523 footprint per Figure 10. Exceeding 250 mA requires derating per Figure 5.
Does BAS521-QF have a specified junction-to-case thermal resistance?
No - the datasheet specifies Rth(j–sp) = 120 K/W (junction-to-solder point) and Rth(j–a) = 500 K/W (junction-to-ambient in free air), but does not define a traditional junction-to-case value. Thermal design must reference the solder point (cathode tab) as the primary heat transfer interface, not an encapsulated case surface.
Can BAS521-QF replace BAS21 in existing designs?
No - BAS21 is a DO-35 through-hole diode rated for 250 V and packaged in axial leaded form. BAS521-QF is SOD523 surface-mount, rated for 300 V, and has faster trr (50 ns vs. 50–100 ns), but differs in footprint, thermal path, and mounting method. Direct replacement requires PCB redesign and validation of thermal and mechanical stress margins.
BAS521-QF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Nexperia USA Inc.
- Series:
- -
- Package/Case:
- SC-79, SOD-523
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Technology:
- Standard
- Voltage - DC Reverse (Vr) (Max):
- 300 V
- Current - Average Rectified (Io):
- 250mA
- Voltage - Forward (Vf) (Max) @ If:
- 1.1 V @ 100 mA
- Speed:
- Fast Recovery =< 500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- 50 ns
- Current - Reverse Leakage @ Vr:
- 150 nA @ 250 V
- Capacitance @ Vr, F:
- 0.4pF @ 0V, 1MHz
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-523
- Operating Temperature - Junction:
- 150°C
BAS521-QF FAQ
1.How can I place an order for BAS521-QF through Aetrix?
Please submit a Request for Quotation (RFQ) for BAS521-QF 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 BAS521-QF reliable?
The price and inventory of BAS521-QF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BAS521-QF is usually 5 days.
3.What payment methods are accepted for BAS521-QF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BAS521-QF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BAS521-QF?
BAS521-QF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BAS521-QF 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 BAS521-QF?
For technical support, including BAS521-QF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BAS521-QF requirements.
6.How does Aetrix verify that BAS521-QF is sourced from the original manufacturer or authorized distributors?
All BAS521-QF 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 BAS521-QF meets industry standards.
7.What is the process for return or replacement of BAS521-QF?
All BAS521-QF units undergo pre-shipment inspection (PSI). If there is an issue with BAS521-QF, 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 BAS521-QF part is unused and in its original packaging.
Return procedure for BAS521-QF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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