BAS40-04 Schottky Diode: Low Leakage & High Withstand Voltage, Optimal Device for High-Speed Small-Signal Circuits

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2026-07-29 40

In high-speed digital circuits, precision signal detection, low-voltage power protection, and portable smart hardware applications, the switching speed, leakage control, and voltage withstand stability of small-signal Schottky diodes directly determine circuit signal integrity and overall standby power consumption. As a classic SOT-23 surface-mount Schottky diode, the BAS40-04 features 40V high reverse withstand voltage, ultra-low nanoampere-level leakage current, and high-speed switching performance. It is widely applied in high-frequency rectification, voltage clamping, freewheeling protection, and anti-reverse connection circuits for medium and small-current scenarios, serving as a highly versatile core discrete device in consumer electronics and micro industrial control circuits. Its key electrical parameters are as follows: DC reverse voltage (Vr): 40V, average rectified current (Io): 200mA, forward voltage drop (Vf): 1V @ 40mA, reverse current (Ir): 200nA @ 30V. With well-balanced and stable parameters, it fully meets the design requirements of low-voltage, high-frequency and low-power micro circuits.

Physical photo of BAS40-04 tiny package

High Withstand Voltage for Versatile Scenarios with Outstanding Circuit Surge Resistance

Compared with conventional 30V small-signal Schottky diodes, the BAS40-04 adopts a 40V high reverse withstand voltage design with sufficient voltage margin and wide compatibility, covering mainstream low-voltage circuit systems of 3.3V, 5V, 12V and 24V. It effectively prevents reverse breakdown and device damage caused by instantaneous voltage surges, electrostatic interference and sudden load fluctuations, greatly improving the operational stability of circuits. It can provide reliable voltage protection for both civilian consumer electronic devices and micro industrial control circuits, complying with diverse design standards for low-voltage power supply equipment.

Ultra-Low Nanoampere-Level Leakage Current to Minimize Overall Standby Power Consumption

Standby power consumption is a critical design indicator for battery-powered micro devices and precision detection circuits. The BAS40-04 delivers an ultra-low reverse leakage current of only 200nA at 30V reverse voltage, far outperforming ordinary diodes of the same specification. Its superior leakage suppression capability significantly reduces invalid power consumption during device standby, effectively extending the battery life of wearable bands, Bluetooth headsets, handheld detectors and other portable devices. Meanwhile, the negligible leakage current avoids interference with weak signal acquisition, ensures high data accuracy of precision sensing and low-voltage detection circuits, and eliminates signal drift and detection errors caused by current leakage.

Stable Conduction Performance for Medium and Small-Current High-Frequency Operation

The BAS40-04 features a rated average rectified current of 200mA, stably meeting the continuous operation demands of various small-power loads. It achieves a low forward voltage drop of 1V at a standard operating current of 40mA, with controllable conduction loss and minimal heat generation. Adopting the majority-carrier conduction mechanism exclusive to Schottky diodes, the device has almost no charge storage effect and an extremely short reverse recovery time, supporting rapid high-frequency switching. Unlike traditional PN-junction diodes that generate obvious voltage spikes and signal distortion during high-frequency operation, the BAS40-04 achieves clean high-frequency rectification, level clamping and coil freewheeling. It is perfectly suitable for high-frequency scenarios such as PWM dimming, high-frequency signal transceiving and micro relay freewheeling, ensuring pure signals and efficient circuit operation.

Miniature Package & Wide-Temperature Stability for Mass Production and Complex Working Conditions

Packaged in the industry-standard SOT-23 miniature surface-mount form factor, the BAS40-04 features a compact size that supports high-density PCB layout, saves internal device space and facilitates the ultra-thin and miniaturized design of smart hardware. It maintains stable performance across a wide temperature range, with negligible drift in core parameters such as forward voltage drop and reverse leakage current under extreme high and low temperatures. Featuring excellent moisture and aging resistance and full RoHS compliance, it adapts to high-speed automatic SMT mass production and guarantees consistent product quality. Even under long-term frequent start-stop operation, ambient temperature fluctuations and short-term load impacts, the device maintains stable performance without attenuation or abnormal leakage rise, delivering outstanding long-term reliability.

Core Application Scenarios

Combining the advantages of high withstand voltage, low leakage, high-speed switching and low power consumption, the BAS40-04 is applicable to a full range of low-voltage small-signal circuits, with core application scenarios as follows:

Wearable Consumer Electronics: Power anti-reverse protection, LED backlight rectification and standby circuit protection for smart watches, Bluetooth earphones and smart bands;
Precision Sensing Equipment: Signal rectification, voltage clamping and signal noise reduction for wireless sensors, infrared induction modules and temperature & humidity detection devices;
Micro Industrial Control: Freewheeling protection for small relays and micro solenoid valves, as well as GPIO level protection for single-chip microcomputers in low-voltage switching circuits;
Portable Devices: Rectification and anti-surge protection for handheld detectors, micro charging modules and small low-voltage power supplies.

Practical Engineering Design Tips

To maximize the performance and service life of the BAS40-04, reasonable safety margins are recommended in circuit design: control the peak circuit voltage within 32V and limit the long-term continuous operating current below 150mA under normal working conditions. For high-frequency circuits, keep the anode and cathode traces short to reduce parasitic inductance and suppress high-frequency switching spikes. Properly widen device pads and add local copper pouring for long-term full-load operation to optimize heat dissipation. Refer to the official datasheet and match optimal circuit parameters according to actual working conditions before mass design.

Product Summary

Featuring 40V high withstand voltage, 200mA rated current, nano-level ultra-low leakage current and high-speed switching capability, the BAS40-04 Schottky diode solves the common drawbacks of ordinary small-signal diodes including insufficient withstand voltage, high leakage and poor high-frequency performance. With well-balanced electrical performance, standardized miniature package and ultra-low power consumption, it serves as a cost-effective universal solution for low-voltage high-frequency small-signal rectification, clamping, freewheeling and anti-reverse circuits. Widely used in consumer electronics, micro industrial control and precision detection fields, it provides efficient, stable and low-power core device support for various micro precision electronic systems.

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