onsemi LV8549MC-AH Motor Driver IC: Datasheet, Application Circuit, and Pin Configuration Guide

The onsemi LV8549MC-AH is a versatile and compact PWM constant-current control bipolar stepping motor driver IC. Designed for space-constrained and power-sensitive applications, it integrates all necessary control and power circuitry into a single package. This makes it an ideal solution for driving bipolar stepper motors in a wide range of consumer and industrial electronics, including printers, scanners, office automation equipment, and robotics.

This guide provides a detailed overview of its key specifications, a typical application circuit, and a comprehensive pin configuration to assist engineers in implementing this driver effectively.

Datasheet Overview and Key Features

The LV8549MC-AH datasheet outlines a device built for performance and reliability. Its primary features include:

Low Supply Voltage Operation: Functions within a range of 2.7 V to 12 V, making it suitable for both 3.3V and 5V logic systems as well as battery-powered applications.

Built-in PWM Current Control: The IC utilizes a fixed-frequency PWM constant-current control system. This allows for precise regulation of motor current, which directly translates to controlled torque and reduced power dissipation.

Low ON-Resistance: The internal output MOSFETs feature a low total H-bridge ON-resistance (RDS(ON)), typically 1.0 Ω (source + sink). This high efficiency minimizes heat generation and maximizes battery life.

Multiple Excitation Modes: It supports full-step, half-step, and quarter-step operation, providing designers with flexibility in balancing motor torque, speed, and resolution.

Integrated Protection Circuits: The IC is robust, featuring critical built-in protections including thermal shutdown (TSD), under-voltage lockout (UVLO), and over-current protection (OCP), safeguarding both the driver and the motor from fault conditions.

Compact Package: Housed in a TSSOP16 package, it offers a small footprint on the PCB, which is crucial for modern, miniaturized designs.

Typical Application Circuit

A standard application circuit for the LV8549MC-AH involves connecting a microcontroller (MCU) to the driver's control pins and the stepper motor to its output pins.

1. Power Supplies: Two voltage inputs are required: `VCC` (logic supply, e.g., 3.3V/5V) and `VM` (motor supply, up to 12V). Both should be decoupled with capacitors close to the IC pins.

2. Microcontroller Interface: The MCU controls the motor by sending signals to four key input pins:

`IN1` and `IN2`: Control the current direction and output state for Coil A.

`IN3` and `IN4`: Control the current direction and output state for Coil B.

3. Current Reference (`VREF`): The peak motor current is set by an external voltage applied to the `VREF1` and `VREF2` pins. This is typically provided by a DAC or a simple voltage divider from the MCU. The relationship is Iout = VREF / (RNF × 5). External sense resistors (`RNF`) connected to the `NFA` and `NFB` pins are crucial for current sensing.

4. Mode Selection: The excitation mode (full, half, quarter step) is selected by applying the appropriate logic levels to the `MODE0` and `MODE1` pins as specified in the datasheet truth table.

5. Outputs: The motor coils are connected between the output pairs: `OUT1A` and `OUT2A` for Channel A, and `OUT1B` and `OUT2B` for Channel B.

Pin Configuration Guide (TSSOP16 Package)

| Pin No. | Pin Name | Description |

| :------ | :----------- | :-------------------------------------------------------------------------- |

| 1 | NFA | Current sense output for channel A. Connect sense resistor to GND. |

| 2 | VREFA | Reference voltage input for setting channel A's peak current. |

| 3 | IN1 | Control input 1 for channel A (H-bridge control). |

| 4 | IN2 | Control input 2 for channel A (H-bridge control). |

| 5 | MODE0 | Excitation mode selection bit 0 (LSB). |

| 6 | MODE1 | Excitation mode selection bit 1 (MSB). |

| 7 | VCC | Logic power supply input (e.g., 3.3V or 5V). |

| 8 | GND | Ground. |

| 9 | IN3 | Control input 1 for channel B (H-bridge control). |

| 10 | IN4 | Control input 2 for channel B (H-bridge control). |

| 11 | VREFB | Reference voltage input for setting channel B's peak current. |

| 12 | NFB | Current sense output for channel B. Connect sense resistor to GND. |

| 13 | OUT2B | Channel B H-bridge output 2. Connect to one side of Motor Coil B. |

| 14 | OUT1B | Channel B H-bridge output 1. Connect to the other side of Motor Coil B. |

| 15 | OUT2A | Channel A H-bridge output 2. Connect to one side of Motor Coil A. |

| 16 | OUT1A | Channel A H-bridge output 1. Connect to the other side of Motor Coil A. |

ICGOODFIND: The onsemi LV8549MC-AH is a highly integrated and efficient solution for driving bipolar stepper motors. Its combination of low voltage operation, advanced PWM current control, multiple stepping modes, and comprehensive protection features makes it an excellent choice for designers seeking reliability and performance in compact applications. Proper attention to the VREF setting and sense resistors is key to optimizing its operation.

Keywords: Stepper Motor Driver, PWM Constant-Current Control, Low ON-Resistance, Thermal Shutdown Protection, TSSOP16 Package.