L298 Dual H-Bridge Motor Driver IC Pins, Working, Applications

Introduction: L298 Dual H-Bridge Motor Driver IC

L298 IC is a dual H-Bridge Motor Driver having high voltage and high current designed to accept standard TTL logic levels (Control Logic) to control different inductive loads like DC motors, relays, solenoids, stepper motors, etc. It is a high-power version of the L293 motor driver IC.

The L298 motor driver is based on the H-bridge configuration which is useful in controlling the direction of rotation of a DC motor. There are four separate power amplifiers are included in L298 IC. Two amplifiers can form H-bridge A and the other two amplifiers can form H-bridge B. Here, one H-bridge is used for polarity switching to control the direction of the motor whereas pair of H bridges are used for controlling the bipolar stepper motor.

In L298 IC, two enable inputs are provided to enable or disable the device independently of the input signals. These enable pins can be used to make all the outputs active simultaneously. All the enable and input pins in L298 IC work with 5V TTL logic to make the connection simple with different types of microcontrollers.

L298 Features and Specifications

The followings are the main features and specifications of L298 IC:

• The operating supply voltage is up to 46V (ranges from +5V to +46V)
• Total DC current is up to 4 A (2A per channel)
• Logical input voltage is up to 1.5 V
• High noise immunity
• TTL controlled inputs
• Power dissipation is 25W
• Low saturation voltage
• Over temperature protection
• The operating temperature ranges from -23°c to – 130°c.
• Storage temperature ranges from -40°c – 150°c.

L298 Pin Configuration & Description

L298 IC is a 15-pin IC. The pin configuration and real image of L298 IC are shown in the figure below:

Pin Description

The function of each pin of L298 IC is described below. This IC includes Dual bridges such as H-bridge A and H-bridge B.

• Pin1 (Current Sensing A): This pin is used to control the flow of load current
• Pin2 (Output 1): This pin is the output pin of the H- Bridge A where the current flows through the load which is monitored at pin 1.
• Pin3 (Output 2): This pin is the output pin of the H- Bridge A where the current flows through the load which is monitored at pin 1.
• Pin4 (VS): This is a voltage supply pin and is connected to a +5V supply.
• Pin5 (Input 1): This pin Control the Input of Bridge A and is compatible with TTL.
• Pin6 (Enable A): This pin is TTL Compatible Enable Input. The LOW state for the disabled.
• Pin7 (Input 2): This pin Control the Input of Bridge A and is compatible with TTL.
• Pin8 (GND): This is a Ground pin.
• Pin9 (Logic Supply Voltage Vss): This pin provides supply voltage for the logic blocks.
• Pin10 (Inputs3): This pin control inputs of bridge-B and is compatible with TTL
• Pin11 (Enable B): This pin is TTL Compatible Enable Input. The LOW state for the disabled.
• Pin12 (Inputs4): This pin control inputs of bridge-B and is compatible with TTL
• Pin 13 (Output 3): This pin is the output pin of the H- bridge B where the current flow through the load is monitored at pin15.
• Pin 14 (Output 4): This pin is the output pin of the H- bridge B where the current flow through the load is monitored at pin15.
• Pin15 (Current Sensing B): This pin is used to control the flow of load current

Refer to L298 Datasheet for more information.

Working of L298 Motor Driver

To understand the working mechanism of L298 IC, Let us take the following simple circuit configuration.

In this circuit, one of the H-bridge of l298 IC is used. This circuit is designed with two push buttons Q1 & Q2 to control the inputs of bridge-A and connected as shown in the circuit diagram. Here, these logic inputs are provided by the Microcontroller or Microprocessor in application circuits.

The four diodes used in the circuit are Flyback diodes used to protect the IC from inductive voltage spikes. Here, enable the pin to determine the function of bridge-A. When the enable pin is pulled high using resister, then bridge-A will enable and start working. Similarly, when it is pulled to GND, it will be disabled and stop working.

After all the circuit is set up, the flow of current between pins OUT 1 and OUT 2 can be varied by pressing the buttons Q1 and Q2. The logic control table is shown below.

When Q1 is pressed, the current flows from OUT1 to OUT2, and the Motor rotates in a clockwise direction. When Q2 is pressed, the current flows from OUT2 to OUT1, and the Motor rotates in the anti-clockwise direction. If both buttons are pressed or released simultaneously the Motor comes to stop immediately. In this way, we can control the motor rotation using L298 IC.

L298 Applications

The L298 Dual H-Bridge Motor Driver IC has multiple applications. It is generally used to control the direction of the motor as well as motor speed. It is applicable in different fields like robotics, embedded, etc.  Here are a few areas, where L298 IC is applicable.

• It is used in applications where a high-power motor driver is required. Since the microcontrollers work on very little voltage and current, L293 motor IC is preferred for high voltage and current applications.
• It is basically used in applications where H-bridge is used. i.e. in H-bridge-based applications
• It is applicable to applications where current control and PWM operable IC are required.
• It is applicable to the applications where the control unit can only provide TTL outputs
• It is also applicable to several real-life applications like Relay drivers, Robotics, automatic door control systems, Weight lifters, etc.