LMD18245 3A, 55V DMOS Full-Bridge Motor Driver
April 1998
LMD18245
3A, 55V DMOS Full-Bridge Motor Driver
General 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 struc-
ture. The LMD18245 controls the motor current via a fixed
off-time chopper technique.
An all DMOS H-bridge power stage delivers continuous out-
put currents up to 3A (6A peak) at supply voltages up to 55V.
The DMOS power switches feature low R
DS(ON)
for high ef-
ficiency, and a diode intrinsic to the DMOS body structure
eliminates the discrete diodes typically required to clamp bi-
polar 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, sim-
plifies implementation of full, half and microstep stepper mo-
tor drives. For higher resolution applications, an external
DAC can be used.
Features
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DMOS power stage rated at 55V and 3A continuous
Low R
DS(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 T
J
= 155˚C
Overcurrent protection
No shoot-through currents
15-lead TO-220 molded power package
Applications
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Full, half and microstep stepper motor drives
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Stepper motor and brushed DC motor servo drives
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Automated factory, medical and office equipment
Functional Block and Connection Diagram
(15-Lead TO-220 Molded Power Package (T) )
DS011878-1
Order Number LMD18245T
See NS Package Number TA15A
© 1998 National Semiconductor Corporation
DS011878
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
