If your power supply loses efficiency at switching transitions, or your motor driver is frying transistors, a slow diode is often the culprit. The 1N5819HW fixes that. It delivers sub-100ns recovery time and a forward voltage below 0.5V. This guide covers specifications, applications, and selection criteria.
Key Takeaways
- The 1N5819HW diode offers a low forward voltage drop below 0.5V.
- Fast reverse recovery time under 100ns enables high-frequency switching.
- Schottky construction makes the 1N5819HW ideal for power rectification.
- Common uses include switch-mode power supplies and freewheeling diodes.
- LCSC stocks multiple 1N5819HW variants for rapid prototyping and production.
What Is a 1N5819HW Diode?
The 1N5819HW is a surface-mount Schottky barrier diode. It uses a metal-semiconductor junction instead of a p-n junction. This construction gives it superior switching speed over standard diodes. The “HW” suffix indicates the compact SOD-123 surface-mount package.
Schottky diodes like the 1N5819HW conduct current with minimal voltage loss. Typical forward voltage is 0.35–0.45V at rated current. In contrast, standard silicon diodes drop 0.6–0.7V. As a result, the 1N5819HW generates less heat and delivers better overall circuit efficiency.
Furthermore, the 1N5819HW works in both rectification and freewheeling circuits. Engineers commonly place it across inductive loads to absorb voltage spikes. In switch-mode power supplies, it recovers charge from the output filter quickly. See our diode guide blog.
Key Features and Advantages
Fast Reverse Recovery
The 1N5819HW achieves reverse recovery time under 100ns. This speed matters in high-frequency switching applications. In contrast, standard diodes require 500+ nanoseconds to turn off. Therefore, faster recovery reduces switching losses significantly.
Lower switching losses also mean less heat output and greater efficiency. This advantage compounds in multi-stage power conversion circuits. Moreover, high-frequency designs operating above 100kHz benefit most. The 1N5819HW produces cleaner switching waveforms with minimal overshoot.
Low Forward Voltage Drop
The 1N5819HW forward voltage of 0.35–0.45V minimizes power dissipation. Lower voltage drop reduces heat generation per unit current. This matters especially in high-current applications where thermal management is critical. For example, a typical rectifier might dissipate 0.5W, while the 1N5819HW dissipates only 0.2W in the same circuit.
In addition, energy savings compound over extended operating periods. Battery-powered devices achieve longer runtime with 1N5819HW diodes. Similarly, renewable energy systems gain improved conversion efficiency. Industrial power supplies also waste less energy as heat.
Compact SOD-123 Package
The SOD-123 package measures 3.81 × 2.76mm with 1.45mm height. It fits dense PCB layouts easily. Through-hole alternatives like the 1N5819 occupy more board space. As a result, surface-mount packaging enables higher component density.
Furthermore, the compact form factor reduces parasitic inductance. Lower inductance means sharper, cleaner switching edges. This benefit supports stable operation in MHz-range switching frequencies. Fine-pitch automation equipment can also place 1N5819HW diodes efficiently.
Technical Specifications of the 1N5819HW
| Parameter | Symbol | Range | Unit | Notes |
| Max Repetitive Peak Voltage | VRRM | 40 | V | Non-repetitive peak is 50V |
| Average Forward Current | IF | 1.0 | A | Requires proper thermal management |
| Peak Forward Current | IFSM | 25 | A | 8.3ms half-sine duration |
| Forward Voltage Drop | VF | 0.35–0.45 | V | At 1A, 25°C |
| Reverse Leakage Current | IR | 5 | µA | At 40V reverse, 25°C |
| Reverse Recovery Time | trr | <100 | ns | Critical for high-frequency use |
| Junction Temperature | TJ | –65 to +150 | °C | Absolute maximum rating |
| Power Dissipation | PD | 1.0 | W | At 25°C with proper cooling |
The 1N5819HW handles currents up to 1A continuously at 25°C. Reverse breakdown occurs at 40V. This voltage rating suits low-voltage circuits well. However, for higher voltage needs, consider the 1N5821HW (60V) or 1N5822HW (30V).
Thermal management becomes critical above 500mA. The SOD-123 package dissipates heat directly to the PCB. Use copper pour under the pads and wider traces to reduce thermal resistance. Otherwise, junction temperature may exceed 150°C at 1A continuous.
Common Applications
1N5819HW Rectification in Switch-Mode Power Supplies
Switch-mode power supplies need fast diodes for the output stage. The 1N5819HW rectifies secondary winding current quickly. It recovers when the switch turns on, preventing energy loss at switching transitions.
In a typical 12V/1A design, the output rectifier sees rapid switching edges. The 1N5819HW’s 100ns recovery time is therefore critical. Slower diodes cause reverse recovery current spikes. These spikes increase EMI and waste power. In contrast, the 1N5819HW keeps spikes minimal and reduces filtering costs.
1N5819HW as a Freewheeling Diode in Motor Drivers
DC motor drivers need freewheeling diodes across the motor winding. When the transistor switches off, the 1N5819HW conducts inductor current. It clamps the voltage spike to one diode drop. Without it, the transistor faces destructive overvoltage.
The 1N5819HW’s low forward voltage also preserves circuit efficiency. Motor stall current can briefly exceed 10A. Verify that 1N5819HW ratings handle your peak current. If needed, place multiple diodes in parallel for higher current capacity.
1N5819HW as a Protection Diode in Switching Regulators
Switching regulators sometimes need external boost diodes to augment internal protection. The 1N5819HW provides secondary protection at minimal cost. Its fast recovery prevents latch-up in harsh switching transitions.
Utility voltage transients occur frequently in industrial environments. The 1N5819HW clamps overvoltage spikes from load switching effectively. Place it close to the load for best protection. Also, add a 100nF ceramic capacitor across the diode pins.
RF and Microwave Detection Circuits
RF diodes operate at gigahertz frequencies in detection circuits. The 1N5819HW’s low junction capacitance enables MHz-to-GHz detection. Its fast switching preserves signal integrity across frequency bands. Matched pairs ensure consistent detector performance across units.
1N5819HW Variants and Selection Guide
The 1N581X family offers several voltage and current options:
| Part Number | Max Voltage | Max Current | Package | Use Case |
| 1N5817 | 20V | 1A | DO-41 | Low-voltage rectification |
| 1N5818 | 30V | 1A | DO-41 | General-purpose rectification |
| 1N5819 | 40V | 1A | DO-41 | High-frequency switching |
| 1N5819HW | 40V | 1A | SOD-123 | Surface-mount rectification |
| 1N5820 | 20V | 3A | DO-41 | Higher current through-hole |
| 1N5821HW | 60V | 1A | SOD-123 | Higher voltage SMD |
| 1N5822HW | 30V | 1A | SOD-123 | Mid-voltage SMD |
Choose the 1N5819HW when you need a surface-mount 40V, 1A Schottky diode. For higher voltage, the 1N5821HW (60V) is the next step up. For higher continuous currents, consider the 1N5820 in through-hole DO-41. If space is the priority, the SOD-123 package of the 1N5819HW is the best choice.
Manufacturing and Procurement
Sourcing and Lead Times
LCSC stocks the 1N5819HW from multiple manufacturers. Typical lead time is 1–2 days for in-stock items. Standard packaging is 500-piece tape and reel. Minimum order quantity is typically 100 units. In addition, small prototyping quantities remain available from many distributors.
Cost ranges from $0.01–$0.05 per unit in volume. Single units for prototyping cost slightly more but remain affordable. Furthermore, bulk pricing drops significantly above 1,000 units. Always check supplier datasheets — some manufacturers rate forward voltage differently.
Test and Reliability Standards for the 1N5819HW
The 1N5819HW meets industrial electronic component standards. Common certifications include AEC-Q200 for automotive use. RoHS compliance is standard for LCSC suppliers. Lead-free solder and conflict-free materials are typical.
Accelerated life testing ensures 100,000+ hour MTBF. Junction temperature cycling from –65°C to +150°C validates robustness. High-temperature reverse bias (HTRB) tests also stress the semiconductor. ESD sensitivity is rated at Class 1B per JEDEC JESD22-A114 (200V–1999V HBM).
Installation and PCB Layout Best Practices
Thermal Management
The SOD-123 package dissipates heat directly to the PCB. Use a 5mm × 5mm copper pour under the pads. Connect the cathode pad (marked with a line) to the return path. Also, minimize the distance from the diode to the power plane.
At 1A continuous current, junction temperature rises 50–75°C above ambient. In a 50°C environment, the junction consequently reaches 100–125°C. Reduce thermal resistance by using a thick copper layer (1oz or more). A ground plane under the entire board also helps distribute heat.
Electrical Connections
Mount the 1N5819HW close to switching nodes and inductive loads. Long traces between the load and diode add parasitic inductance. In turn, inductance causes voltage overshoot and ringing. Therefore, keep traces under 10mm length when possible.
Use a 100nF ceramic bypass capacitor directly across the diode pads. This capacitor absorbs high-frequency noise effectively. Position it within 5mm of the diode. Low-ESR capacitors also reduce voltage spikes more effectively.
Polarity Verification
The cathode is marked with a dark band on the SOD-123 body. This end connects to the higher potential in a rectifier. In a freewheeling circuit, the cathode connects to the power rail. Reverse polarity can destroy the 1N5819HW instantly.
Frequently Asked Questions
What Is the Difference Between the 1N5819HW and the 1N5819?
The 1N5819HW is surface-mount (SOD-123), while the 1N5819 is through-hole (DO-41). Both are 40V, 1A Schottky diodes with identical electrical characteristics. Choose the 1N5819HW for modern PCB designs where space is limited. Use the 1N5819 for through-hole prototyping or legacy circuits that require axial-lead components.
Can I Replace a Standard Diode with the 1N5819HW?
In most rectification circuits, yes. The 1N5819HW offers superior speed and efficiency compared to standard silicon diodes. However, first verify that 1N5819HW voltage and current ratings exceed your circuit needs. Note that some circuits exploit a longer reverse recovery time — switching to the 1N5819HW might cause unexpected behavior in those designs. Therefore, test thoroughly before volume production.
What Happens If I Exceed the 1N5819HW 1A Current Rating?
Peak currents up to 25A are permissible for brief periods under 8.3ms. However, sustained currents above 1A cause excessive heat and junction temperature rise. The diode may fail thermally after just a few minutes of overload. For higher continuous currents, either parallel multiple 1N5819HW diodes or select a higher-rated part such as the 1N5820 (3A, DO-41).
How Do I Calculate 1N5819HW Thermal Dissipation?
Power dissipation equals VF × IF. At 0.4V forward voltage and 1A current, dissipation is 0.4W. With a typical PCB thermal resistance of 500K/W for the SOD-123 package, junction temperature rise equals 0.4W × 500K/W = 200K. This result is excessive and demands thermal improvements. Reduce thermal resistance to 200K/W or below for acceptable 1N5819HW performance.
Is the 1N5819HW Suitable for High-Frequency Rectification?
Yes. The sub-100ns recovery time supports switching frequencies above 100kHz. At 500kHz, the 1N5819HW delivers clean rectification with minimal ringing. However, for GHz-range detection circuits, verify junction capacitance against your specific frequency band. Capacitance rises at lower reverse voltages, so check detailed datasheets before finalizing your design.
Find What You Need on LCSC
Finding in-stock 1N5819HW variants on LCSC is straightforward. Filter by manufacturer, reel quantity, and lead time to match your project needs. Most 1N5819HW units ship within 1–2 days. Order in any quantity — from prototyping samples to full production runs.
