Datasheets»National Semiconductor (acquired by TI (Texas Instruments))»LMD18245 Datasheet

LMD18245 Datasheet

Download or read online National Semiconductor LMD18245 3A, 55V DMOS Full-Bridge Motor Driver pdf datasheet.



Page
1 of 18
next
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 de-
vice combines bipolar and CMOS control and protection cir-
cuitry 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 out-
put currents up to 3A (6A peak) at supply voltages up to
55V The DMOS power switches feature low R
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 mo-
tor A four-bit digital-to-analog converter (DAC) provides a
digital path for controlling the motor current and by exten-
sion simplifies implementation of full half and microstep
stepper motor drives For higher resolution applications an
external DAC can be used
Functional Block and Connection Diagram
C 1996 National Semiconductor Corporation
TL H 11878
Features
DMOS power stage rated at 55V and 3A continuous
Y
Low R
of typically 0 3
Y
DS(ON)
Internal clamp diodes
Y
Low-loss current sensing method
Y
Digital or analog control of motor current
Y
TTL and CMOS compatible inputs
Y
Thermal shutdown (outputs off) at T
Y
Overcurrent protection
Y
No shoot-through currents
Y
15-lead TO-220 molded power package
Y
for
DS(ON)
Applications
Full half and microstep stepper motor drives
Y
Stepper motor and brushed DC motor servo drives
Y
Automated factory medical and office equipment
Y
(15-Lead TO-220 Molded Power Package (T) )
Order Number LMD18245T
See NS Package Number TA15A
RRD-B30M96 Printed in U S A
September 1996
per power switch
155 C
e
J
TL H 11878 – 1
http
www national com

Summary of Contents

Page 1

... The multi-technology process used to build the de- vice combines bipolar and CMOS control and protection cir- cuitry 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 out- ...

Page 2

... Absolute Maximum Ratings If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications DC Voltage at OUT 1 V and OUT 2 CC COMP OUT BRAKE DIRECTION CS OUT and DAC REF DC Voltage PGND to SGND Continuous Load Current ...

Page 3

Electrical Characteristics face limits apply over the operating temperature range (Note 2) (Continued Symbol Parameter CURRENT SENSE AMPLIFIER Current Sense Output Current Sense Linearity Error Current Sense Offset DIGITAL-TO-ANALOG CONVERTER (DAC) Resolution Monotonicity Total Unadjusted ...

Page 4

Electrical Characteristics face limits apply over the operating temperature range (Note 2) (Continued Note 1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Electrical specifications do not apply when operating ...

Page 5

... Connection Diagram Top View 15-Lead TO-220 Molded Power Package Order Number LMD18245T See NS Package Number TA15A Pinout Descriptions (See Functional Block and Connection Diagrams) Pin 1 OUT 1 Output node of the first half H-bridge Pin 2 COMP OUT Output of the comparator If the voltage at CS OUT exceeds that provided by the DAC the compara- ...

Page 6

Functional Descriptions ( 118783 ( 118786 FIGURE 1 Chopper Amplifier Chopping States Full V Winding (b) and (e) Winding Current Decays During a Change in the Direction of the Winding Current (c) and (f) and the ...

Page 7

... Functional Descriptions (Continued) THE LMD18245 CHOPPER AMPLIFIER The LMD18245 incorporates all the circuit blocks needed to implement a fixed off-time chopper amplifier These blocks include an all DMOS full H-bridge with clamp diodes an amplifier for sensing the load current a comparator a monostable and a DAC for digital control of the chopping ...

Page 8

Functional Descriptions THE CURRENT SENSE AMPLIFIER Many transistor cells in parallel make up the DMOS power switches The current sense amplifier (Figure 4) uses a small fraction of the cells of both upper switches to provide a unique low-loss means ...

Page 9

Applications Information POWER SUPPLY BYPASSING Step changes in current drawn from the power supply occur repeatedly during normal operation and may cause large voltage spikes across inductance in the power supply line Care must be taken to limit voltage spikes ...

Page 10

The Typical Application Figure 6 shows the typical application the power stage of a chopper drive for bipolar stepper motors The 20 k and capacitor connected between RC and ground set the off-time at about 48 s ...

Page 11

The Typical Application (Continued) ONE-PHASE-ON FULL STEP DRIVE (WAVE DRIVE) To make the motor take full steps windings A and B can be energized in the sequence where A represents winding A energized with current ...

Page 12

The Typical Application M4 A through through BRAKE A BRAKE FIGURE 8 Winding Currents and Digital Control Signals for Two-Phase-On Drive FIGURE 9 Winding Current and Voltage ...

Page 13

The Typical Application (Continued) HALF STEP DRIVE WITHOUT TORQUE COMPENSATION To make the motor take half steps windings A and B can be energized in the sequence BRAKE A ...

Page 14

The Typical Application HALF STEP DRIVE WITH TORQUE COMPENSATION To make the motor take half steps the windings can also be energized with sinusoidal currents (Figure 11) Controlling the winding currents in the fashion shown doubles the step resolution without ...

Page 15

The Typical Application (Continued) 90 ELECTRICAL FULL STEP l cos FORWARD 45 0 707 90 135 0 707 180 REVERSE 225 0 707 l 270 315 0 707 REPEAT FIGURE 12 Lookup Table for Half Step Drive ...

Page 16

Test Circuit and Switching Time Definitions http www national com TL H 11878 – ...

Page 17

17 http www national com ...

Page 18

... Italiano National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications Order Number LMD18245T NS Package Number TA15A 2 A critical component is any component of a life ...

Comments to this Datasheet