BAT54A Schottky Diode : Pin Configuration & Its Applications

The Schottky diode is one type of metal-semiconductor diode with a low voltage drop of 0.15V to 0.45V and a very high switching speed. These are also called Schottky barrier diodes or hot-carrier Schottky diodes. These diodes are used in various applications such as wave shaping, rectification, protection circuits, switching, and signal conditioning. The Schottky diodes with different series are available in the market. This article gives a brief description of the BAT54A Schottky Diode.

What is BAT54A Schottky Diode?

BAT54A is a Schottky diode available in the Surface Mount Devices (SMD) package that provides low turn-on voltage drop and quick switching functionality. This device is equipped with a PN connection protection/guard ring for ESD and transient protection and is also a “green” device, RoHS compliant. These are formed by a PN-junction of a metal-semiconductor-metal just like a normal diode. These are planar Schottky diodes with an integrated guard ring for protection.

BAT54A Schottky Diode
BAT54A Schottky Diode

Generally, these Schottky diodes are used in protection and rectifier circuits. Devices rated for low voltage drop during conduction are required in low voltage circuits where voltage drop during conduction is unacceptable.

It is used in circuits where power efficiency is critical. The device’s ability to provide significant current at low voltage drop provides the high efficiency required for battery-powered systems.

It is designed for recovery (forward conduction to reverse voltage blocking) and uses only 5 ns to drive high-frequency applications.

BAT54A Pin Configuration/Pin Diagram:

The BAT54A Schottky diode is a 3-terminal diode as shown in the below pin diagram. It is designed with two Schottky diodes as shown below. The three terminals are cathode 1, cathode 2, and anode.

BAT54A Pin Diagram
BAT54A Pin Diagram

Pin 1: Cathode 1: It is a negative terminal of the 1st Schottky diode as shown in the below diagram. The current goes out from the device through this terminal.

Pin 2: Cathode 2: It is the negative terminal of the 2nd Schottky diode. The current goes out from the device through this terminal.

Pin 3: Anode: It is a common positive terminal of the two connected Schottky diodes. Through this terminal, the current flows into the device.

The alternatives of BAT54A Schottky diodes are BAT54 Schottky diodes, BAT54S Schottky diodes and BAT54C Schottky diodes.

BAT54A Schottky Diode Specifications:

The BAT54A Schottky diode specifications and electrical characteristics are given below.

  • The forward voltage drop is low: 150-450mV.
  • The conduction losses are very small.
  • The switching speed is extremely fast.
  • Efficiency is high.
  • It is a RoHS-compliant and load-free device.
  • The maximum forward continuous current is 200mA.
  • The maximum reverse voltage is 30V.
  • The maximum forward surge current is 600mA.
  • The range of operating temperature is -65°C-150°C.
  • The maximum power dissipation is 200mW.
  • Available in SMD package.
  • Low capacitance: 10pF @ f=1MHz, Vr = 1V.

The other characteristics are,

  • The reverse voltage is 30V.
  • The forward current @25°C is 200mA.
  • The repetitive peak forward current @25°C is 300mA.
  • Non-repetitive peak forward current @ square wave of tp<10ms is 600mA.
  • The junction temperature is 150°C.
  • Ambient temperature is -55°C to 150°C.
  • Storage temperature is -65°C to 150°C.
  • The device is mounted on PCB, single-sided copper, tin-plated, and standard footprint.
  • The thermal resistance from junction to ambient in free air is 500K/W.
  • Reverse recovery time is 5nS.
  • The forward voltage @ If (forward current) = 0.1mA is 240mV, @ If = 1mA is 320mV, @ If = 10mA is 400mV, @ If = 30mA is 500mV, @ If = 100mA is 800mV.
  • The reverse current @ reverse voltage of 25V is 2microAmps.

Circuit Diagram /How to Use a BAT54A Schottky Diode:

The BAT54A Schottky diode works similar to any other rectifier diode and can be installed in protection rectifier circuits. Therefore, the characteristics of BAT54A can be expressed as follows.

Circuit Diagram
Circuit Diagram
  • It can conduct in the direction of the forward bias only when the positive anode is connected to positive voltage and the cathode connected to the ground.
  • Will only flow with a leakage current of up to 0.1 mA in opposite directions only when the positive anode and cathode are connected to the ground.
  • In forward biased condition, a maximum of 1 V appears across the device, and when reversing biased, the full supply voltage appears at the device.

In the above circuit, the BAT54A Schottky diode is used as a protection diode for the microcontroller. Here, the power supply powers the microcontroller, and the diodes are connected in series for protection.

Now consider an application of how to use a BAT54A Schottky diode that operates as a protection device for the microcontroller or microprocessor. The components required are a power supply unit with 3.5V, BAT54A Schottky diode, and Microprocessor or Microcontroller.

The circuit diagram of a BAT54A Schottky diode to protect the microcontroller unit from the reverse voltage is shown in the figure below.

From the above circuit, we can observe that the 3.5V supply pin of the power supply unit is connected to the common anode terminal of the BAT54A Schottky diode and the ground pin of the power supply unit is connected to the ground pin of the microcontroller/microprocessor unit. The common cathode 1 and cathode terminals of the BAT54A Schottky diode are connected to the VCC pin of the microcontroller/microprocessor unit.

When the power supply supplies current, the diode is forward biased and current starts to flow. The current flowing in the microcontroller creates a voltage very close to the power supply voltage because the device has a very small drop in forward conduction.

Now consider for a moment, that the polarity of the power supply is connected incorrectly. In this state, the diode is reverse biased and no current flows through the circuit during this condition, according to the specifications of the BAT54A. So, in this error connection, the zero voltage appears across the microcontroller, so no error occurs and protects it from damage.

In the above circuit diagram, the BAT54A Schottky diode is used to protect the sensitive microcontroller from reverse voltage, and in the same way, the device can be used in other application circuits.

Applications/Where to Use

The following are the applications of the BAT54A Schottky diode.

  • Used in AC-DC filters.
  • Used in voltage regulators.
  • Used in applications of ultra-high-speed switching.
  • Used in protection circuits.
  • Used in protection devices.
  • Used for line detectors.
  • Used in reverse polarity protection.
  • Used in voltage damping circuits.

Please refer to this link for BAT54A Schottky Diode Datasheet.

Thus, this is all about an overview of BAT54A Schottky diodes. Generally, the Schottky diodes are used for low turn-on voltage, low-loss energy, and fast recovery time at higher efficiencies. These diodes became an ideal choice for semiconductor diodes for several applications such as detector diodes, RF mixers, power rectifier circuits, solar cell applications, etc.