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Nexperia USA Inc. BAS521B-QX
- Part No.:
- BAS521B-QX
- Manufacturer:
- Nexperia USA Inc.
- Category:
- Single Diodes
- Package:
- SC-79, SOD-523
- Datasheet:
-
BAS521B-QX.pdf
- Description:
- BAS521B-Q/SOD523/SC-79
- Quantity:
- Payment:
- Shipping:
Inventory:5,255
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Product details
Overview
BAS521B-Q from Nexperia is a high-voltage switching diode in SOD523 (SC-79) package, rated for 250 V repetitive peak reverse voltage, 50 ns reverse recovery time, and 250 mA forward current. It serves as a fast, low-leakage clamping and polarity protection device in automotive power management and signal routing circuits.
For engineers reviewing the BAS521B-Q datasheet, BAS521B-Q pinout, BAS521B-Q application, or BAS521B-Q equivalent, this page delivers verified electrical parameters, AEC-Q101 qualification status, thermal resistance values, and real-world use context for high-reliability automotive and industrial switching designs.
Technical Context
This diode employs a planar epitaxial silicon structure optimized for fast minority-carrier recombination, enabling ≤50 ns trr under IF = IR = 30 mA test conditions with 100 Ω load. Its low 2 pF capacitance at 0 V and 1 MHz supports RF-adjacent signal path isolation.
The device operates across −55 °C to +150 °C junction temperature, with thermal resistance Rth(j-a) = 500 K/W on FR4 PCB and Rth(j-sp) = 95 K/W to cathode solder point-critical for transient pulse handling in automotive load-dump scenarios.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRRM | 250 V repetitive peak reverse voltage - supports 24 V/48 V automotive systems with ≥2× safety margin against transients. |
| trr | 50 ns reverse recovery time - enables clean switching up to ~10 MHz in flyback snubbers and digital signal clamping. |
| IR | 100 nA reverse leakage at 200 V, 25 °C - ensures minimal standby power loss in battery-backed circuits. |
| Cd | 2 pF diode capacitance at 0 V, 1 MHz - preserves signal integrity in high-speed data line protection (e.g., CAN FD stubs). |
| IFSM | 9.4 A non-repetitive peak forward current (tp = 50 µs) - withstands automotive load-dump surges without failure. |
| Ptot | 380 mW total power dissipation at Tamb ≤ 25 °C - defines thermal derating envelope for compact PCB layouts. |
Pinout & Package
Package: SOD523 (SC-79), ultra-small surface-mount plastic package measuring 1.2 mm × 0.8 mm × 0.6 mm, leadless, with tin-plated copper pads per JEDEC standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Cathode (K) | Primary current exit terminal; connects to PCB cathode pad (1 cm² recommended for thermal relief); marked "S2" on top surface. |
| 2 | Anode (A) | Current entry terminal; routed to supply rail or signal source; requires controlled trace width for 250 mA DC operation. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive-grade reliability including HTOL, TC, HAST, and ESD (HBM ≥ 8 kV), enabling drop-in use in ADAS ECUs and body controllers. |
| Ultra-low trr | ≤50 ns reverse recovery ensures minimal switching loss and reduced EMI generation in 100 kHz–1 MHz DC-DC auxiliary supplies. |
| Low Cd & IR | 2 pF capacitance and 100 nA leakage jointly enable high-fidelity clamping of 10–100 MHz signals without loading or DC offset drift. |
| SOD523 footprint | 1.2 mm × 0.8 mm outline allows placement in space-constrained modules (e.g., LIN transceiver subassemblies, sensor interface boards). |
Applications
| Automotive Load-Dump Protection | CAN FD Signal Clamping |
|---|---|
Use Scenario: Protecting 12 V/24 V microcontroller I/O pins during ISO 7637-2 Pulse 5a load-dump events (up to 60 V, 100 ms). IC Role / Device Role / Timing Role: Fast clamping diode shunting surge energy to ground via low-inductance layout; activated within nanoseconds of overvoltage onset. Use Value: Prevents latch-up or permanent damage to MCU GPIOs while maintaining <100 ns response latency and <2 pF signal path loading. |
Use Scenario: Bidirectional voltage limiting on CAN FD differential pair (CANH/CANL) to suppress ESD and bus fault transients. IC Role / Device Role / Timing Role: Low-capacitance clamp placed across bus lines; conducts only above ±30 V to preserve signal rise/fall times. Use Value: Enables >5 Mbps CAN FD bit rates by limiting added capacitance to ≤2 pF per line and leakage to <100 nA at 12 V common-mode. |
| Reverse Polarity Input Protection | High-Speed Flyback Snubber |
Use Scenario: Series-connected protection for 5 V/3.3 V power rails in telematics modules where incorrect battery connection must not damage downstream regulators. IC Role / Device Role / Timing Role: Anode-to-input, cathode-to-load configuration; blocks reverse current while passing forward current with VF ≤ 1.25 V @ 200 mA. Use Value: Delivers <1.3 V forward drop at full rated current, minimizing voltage loss and thermal rise in compact power domains. |
Use Scenario: RC-snubber replacement in 100–500 kHz flyback converters driving LED drivers or sensor bias supplies. IC Role / Device Role / Timing Role: Fast recovery diode in series with snubber capacitor to absorb leakage inductance energy without oscillation. Use Value: Reduces snubber losses by >30% versus standard rectifiers due to 50 ns trr and 250 V VR rating matching MOSFET VDS stress. |
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 NSVBAS521LT1G | Same SOD523 package, identical VRRM (250 V) and trr (50 ns), but IR = 200 nA @ 200 V - double the leakage of BAS521B-Q. | Acceptable in non-battery-critical applications; unsuitable for always-on vehicle modules where nanoampere leakage impacts quiescent current budget. | Select when cost sensitivity outweighs leakage requirements and AEC-Q101 documentation alignment is secondary. |
| Vishay VS-50WQ03FNTR-M3 | TO-277 package, higher IF (3 A), lower VF (0.38 V), but trr = 100 ns and Cd = 100 pF - slower and far more capacitive. | Only viable in high-current, low-frequency (<100 kHz) clamping; incompatible with high-speed signal paths or space-constrained PCBs. | Choose only for legacy TO-277 board reuse or where thermal mass > speed is prioritized. |
Compared with NSVBAS521LT1G and VS-50WQ03FNTR-M3, the BAS521B-Q uniquely balances ultra-low leakage (100 nA), minimal capacitance (2 pF), and AEC-Q101 compliance in the smallest SOD523 footprint-making it optimal for next-gen automotive signal integrity and low-power always-on systems.
Availability
BAS521B-Q is available at Aetrix Electronics and suitable for automotive ECU protection, CAN FD interface clamping, and reverse polarity input circuits requiring stable component supply across extended product lifecycles.
Supply support for BAS521B-Q 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 logic, discrete, and MOSFET devices for automotive, industrial, and mobile markets.
The BAS521B-Q belongs to Nexperia's AEC-Q101-qualified high-voltage switching diode family, engineered specifically for robust transient suppression and signal integrity preservation in harsh automotive environments.
FAQ
What is the maximum continuous forward current for BAS521B-Q?
The maximum continuous forward current is 250 mA at ambient temperature ≤25 °C on an FR4 PCB with single-sided copper and standard footprint. Derating is required above 25 °C: current drops linearly to zero at 150 °C junction temperature, governed by the 380 mW power dissipation limit and 500 K/W thermal resistance.
Does BAS521B-Q support reflow soldering per J-STD-020?
Yes-BAS521B-Q is qualified for lead-free reflow per J-STD-020D, with peak temperature up to 260 °C for ≤30 seconds. The recommended footprint uses 0.5 mm wide solder lands and 0.4 mm solder resist openings per the SC-79 layout in Figure 10 of the datasheet, ensuring reliable wetting and void minimization.
How does the 2 pF capacitance affect CAN FD signal integrity?
At 2 pF, the diode adds negligible loading to CAN FD differential pairs: insertion loss remains <0.1 dB up to 10 MHz, preserving rise/fall times below 1 ns and meeting ISO 11898-2 eye diagram mask requirements. This enables direct placement across CANH/CANL without external impedance compensation.
Is BAS521B-Q suitable for bidirectional ESD protection?
No-BAS521B-Q is a unidirectional diode (anode/cathode asymmetry). For bidirectional ESD protection, a dual-diode array like PESD5V0S1BA (also AEC-Q101 qualified) is required. BAS521B-Q functions only as a unidirectional clamp or rectifier, conducting only when cathode is more positive than anode.
BAS521B-QX 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):
- 200 V
- Current - Average Rectified (Io):
- 250mA
- Voltage - Forward (Vf) (Max) @ If:
- 1.25 V @ 200 mA
- Speed:
- Fast Recovery =< 500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- 50 ns
- Current - Reverse Leakage @ Vr:
- 100 nA @ 200 V
- Capacitance @ Vr, F:
- 2pF @ 0V, 1MHz
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-523
- Operating Temperature - Junction:
- 150°C
BAS521B-QX FAQ
1.How can I place an order for BAS521B-QX through Aetrix?
Please submit a Request for Quotation (RFQ) for BAS521B-QX 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 BAS521B-QX reliable?
The price and inventory of BAS521B-QX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BAS521B-QX is usually 5 days.
3.What payment methods are accepted for BAS521B-QX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BAS521B-QX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BAS521B-QX?
BAS521B-QX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BAS521B-QX 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 BAS521B-QX?
For technical support, including BAS521B-QX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BAS521B-QX requirements.
6.How does Aetrix verify that BAS521B-QX is sourced from the original manufacturer or authorized distributors?
All BAS521B-QX 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 BAS521B-QX meets industry standards.
7.What is the process for return or replacement of BAS521B-QX?
All BAS521B-QX units undergo pre-shipment inspection (PSI). If there is an issue with BAS521B-QX, 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 BAS521B-QX part is unused and in its original packaging.
Return procedure for BAS521B-QX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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