1FEATURES

2• DMOS Power Stage Rated at 55V and 3A

Continuous

• Low RDS(ON) of Typically 0.3Ω per Power

Switch

• Internal Clamp Diodes

• Low-loss Current Sensing Method

• Digital or Analog Control of Motor Current

• TTL and CMOS Compatible Inputs

• Thermal Shutdown (Outputs Off) at TJ = 155°C

• Overcurrent Protection

• No Shoot-Through Currents

• 15-lead Package

APPLICATIONS

• Full, Half and Microstep Stepper Motor Drives

• Stepper Motor and Brushed DC Motor Servo

Drives

• Automated Factory, Medical and Office

Equipment

DESCRIPTION

The LMD18245 full-bridge power amplifier

incorporates all the circuit blocks required to drive

and control current in a brushed type DC motor or

one phase of a bipolar stepper motor. The multi-

technology process used to build the device

combines bipolar and CMOS control and protection

circuitry with DMOS power switches on the same

monolithic structure. The LMD18245 controls the

motor current via a fixed off-time chopper technique.

An all DMOS H-bridge power stage delivers

continuous output currents up to 3A (6A peak) at

supply voltages up to 55V. The DMOS power

switches feature low RDS(ON) for high efficiency, and a

diode intrinsic to the DMOS body structure eliminates

the discrete diodes typically required to clamp bipolar

power stages.

An innovative current sensing method eliminates the

power loss associated with a sense resistor in series

with the motor. A four-bit digital-to-analog converter

(DAC) provides a digital path for controlling the motor

current, and, by extension, simplifies implementation of full, half and microstep stepper motor drives. For

higher resolution applications, an external DAC can

be used.