LDH40 - High-Speed Switching Diode | Vishay
MPN: LDH40 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.12 | $0.12 |
| 10 | $0.1 | $1.00 |
| 100 | $0.08 | $8.00 |
| 500 | $0.06 | $30.00 |
| 1,000 | $0.05 | $50.00 |
Drop-in alternatives for LDH40 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
1N4148
β Drop-Inπ Reference alternative (not in catalog)
1N914
β Drop-Inπ Reference alternative (not in catalog)
BAV21
β Drop-Inπ Reference alternative (not in catalog)
LDH40 Maximum Ratings & Electrical Characteristics
| Diode Type | Switching Diode |
| Maximum Repetitive Peak Reverse Voltage (VRRM) | 80 V |
| Maximum RMS Reverse Voltage (VRMS) | 56 V |
| Maximum DC Blocking Voltage (VDC) | 80 V |
| Maximum Average Forward Rectified Current (IF(AV)) | 300 mA |
| Maximum Peak Forward Surge Current (IFSM) | 2 A |
| Maximum Forward Voltage (VF) | 1 V at 100 mA |
| Maximum Reverse Recovery Time (trr) | 4 ns |
| Maximum Reverse Leakage Current (IR) | 25 nA at 80 V |
| Junction Capacitance (CJ) | 2 pF at 0 V, 1 MHz |
| Power Dissipation (PD) | 500 mW |
| Operating Temperature Range | -65Β°C to +175Β°C |
| Package | DO-35 (DO-204AH) |
| Mounting Type | Through Hole |
| RoHS Status | Compliant |
| Lead-Free | Yes |
LDH40 Pin Configuration
| Pin 1 | Anode β Anode terminal, current flows in this direction |
| Pin 2 | Cathode β Cathode terminal, marked with a band |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
LDH40 is suitable for 6 applications: Signal Clamping, Voltage Limiting, Logic Gating, RF Detection, Audio Envelope Detection, Protection Circuits.
Signal Clamping
The LDH40 is used for signal clamping to limit voltage levels in analog circuits. Its fast reverse recovery time (4 ns) ensures minimal distortion of high-frequency signals, while its low forward voltage (1 V at 100 mA) provides precise clamping thresholds. In a typical clamping circuit, the diode is placed in parallel with the signal path, conducting when the voltage exceeds a set level, thereby protecting downstream components from overvoltage. The low junction capacitance (2 pF) minimizes signal attenuation, making it suitable for RF and video applications. Compared to slower diodes, the LDH40 reduces clamping-induced waveform distortion, preserving signal integrity in high-speed data lines.
Recommended
Voltage Limiting
In voltage limiting circuits, the LDH40 protects sensitive components by conducting when the voltage exceeds a safe threshold. Its 80 V reverse voltage rating provides adequate headroom for typical low-voltage applications, while its 300 mA forward current handles transient currents without damage. The diode's fast recovery ensures rapid response to overvoltage events, reducing the risk of damage to downstream circuitry. In a typical protection circuit, the LDH40 is connected across the input terminals, shunting excess voltage to ground. Its low leakage current (25 nA) ensures minimal power loss during normal operation, making it suitable for battery-powered devices. The DO-35 package allows easy integration into existing PCB designs.
Recommended
Logic Gating
The LDH40 is used in logic gating circuits to implement AND and OR functions using diode-resistor logic. Its fast switching speed (4 ns) enables high-speed logic operations, while its low forward voltage ensures clean logic levels. In a typical diode logic gate, multiple diodes are connected to a common output node, with each diode representing an input. The LDH40's low capacitance (2 pF) reduces propagation delays, making it suitable for high-frequency digital circuits. Compared to discrete logic gates, diode logic using the LDH40 offers a simple and cost-effective solution for basic logic functions. However, it is limited by its lack of gain, so it is often used in combination with amplifiers or buffers.
Recommended
RF Detection
The LDH40 is employed in RF detection circuits to demodulate amplitude-modulated signals. Its fast reverse recovery time (4 ns) and low junction capacitance (2 pF) allow it to respond to high-frequency carriers, making it suitable for RF applications up to several hundred MHz. In a typical detector circuit, the diode rectifies the RF signal, producing a DC output proportional to the signal amplitude. The LDH40's low forward voltage (1 V) ensures high sensitivity, while its low leakage current (25 nA) minimizes noise. Compared to Schottky diodes, the LDH40 offers a higher reverse voltage rating, making it more robust in applications with higher voltage transients. Its DO-35 package is suitable for through-hole RF designs.
Recommended
Audio Envelope Detection
The LDH40 is used in audio envelope detection circuits to extract the amplitude envelope of audio signals. Its fast response time (4 ns) ensures accurate tracking of signal variations, while its low forward voltage (1 V) provides a linear detection characteristic. In a typical envelope detector, the diode rectifies the audio signal, and a capacitor filters the output to produce a smooth envelope. The LDH40's low capacitance (2 pF) minimizes high-frequency losses, preserving audio quality. Compared to other diodes, the LDH40 offers a good balance of speed and voltage rating, making it suitable for audio processing applications. Its DO-35 package is easy to integrate into audio circuits.
Recommended
Protection Circuits
The LDH40 is used in protection circuits to safeguard sensitive components from overvoltage and reverse polarity. Its 80 V reverse voltage rating provides a robust blocking capability, while its 300 mA forward current handles fault currents. In a typical protection circuit, the diode is placed in series or parallel with the load to prevent damage from voltage spikes. The LDH40's fast recovery time (4 ns) ensures rapid response to transients, reducing the risk of component failure. Its low leakage current (25 nA) minimizes power loss during normal operation, making it suitable for energy-efficient designs. The DO-35 package allows easy integration into existing protection circuits.
Recommended
Recommended Products Summary
Engineering reference data for LDH40 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | 1N4148 | 1N914 | BAV21 |
|---|---|---|---|---|
| Package | DO-35 | DO-35 | DO-35 | DO-35 |
| Brand | Vishay | Vishay | Vishay | Vishay |
| Maximum Reverse Voltage | 80 V | 75 V | 75 V | 200 V |
| Forward Current | 300 mA | 300 mA | 300 mA | 250 mA |
| Reverse Recovery Time | 4 ns | 4 ns | 4 ns | 50 ns |
| Forward Voltage | 1 V at 100 mA | 1 V at 100 mA | 1 V at 100 mA | 1 V at 100 mA |
| Junction Capacitance | 2 pF | 2 pF | 2 pF | 2 pF |
| Power Dissipation | 500 mW | 500 mW | 500 mW | 500 mW |
Key Differentiators
- Higher reverse voltage rating (80 V) compared to common alternatives (vs 1N4148)
- Fast reverse recovery time (4 ns) for high-speed switching (vs BAV21)
- Low junction capacitance (2 pF) for RF applications (vs 1N914)
Design Notes
For high-frequency applications, keep the leads of the LDH40 as short as possible to minimize parasitic inductance. Use a ground plane beneath the diode to reduce loop area and improve switching performance. The DO-35 package is through-hole, so ensure proper hole sizing and solder fillet for reliable mechanical and electrical connection.
The LDH40 has a power dissipation rating of 500 mW. In continuous operation, ensure that the ambient temperature and PCB layout allow for adequate heat dissipation. For currents near the maximum rating, consider derating based on the thermal resistance of the package and the surrounding environment.
Do not exceed the maximum reverse voltage of 80 V, as this can cause breakdown and permanent damage. Also, avoid exceeding the forward current rating of 300 mA, which can lead to overheating. When using the diode in high-frequency circuits, be aware of its junction capacitance (2 pF) and its effect on signal integrity.
Compliance Information
RoHS compliant and lead-free per Vishay datasheet. AEC-Q100 not applicable for discrete diodes.
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