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.