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부품번호 | LMD18245 기능 |
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기능 | 3A / 55V DMOS Full-Bridge Motor Driver | ||
제조업체 | National Semiconductor | ||
로고 | |||
전체 18 페이지수
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 RDS(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
n DMOS power stage rated at 55V and 3A continuous
n Low RDS(ON) of typically 0.3Ω per power switch
n Internal clamp diodes
n Low-loss current sensing method
n Digital or analog control of motor current
n TTL and CMOS compatible inputs
n Thermal shutdown (outputs off) at TJ = 155˚C
n Overcurrent protection
n No shoot-through currents
n 15-lead TO-220 molded power package
Applications
n Full, half and microstep stepper motor drives
n Stepper motor and brushed DC motor servo drives
n Automated factory, medical and office equipment
Functional Block and Connection Diagram (15-Lead TO-220 Molded Power Package (T) )
Order Number LMD18245T
See NS Package Number TA15A
© 1998 National Semiconductor Corporation DS011878
DS011878-1
www.national.com
Typical Performance Characteristics
RDS(ON) vs Temperature
RDS(ON) vs Load Current
RDS(ON) vs
Supply Voltage
DS011878-29
Current Sense Output
vs Load Current
DS011878-30
Supply Current vs
Supply Voltage
DS011878-31
Supply Current vs
Temperature
DS011878-32
DS011878-33
DS011878-34
www.national.com
4
4페이지 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
threshold. Also incorporated are logic, level shifting and drive
blocks for digital control of the direction of the load current
and braking.
THE H-BRIDGE
The power stage consists of four DMOS power switches and
associated body diodes connected in an H-bridge configura-
tion (Figure 2 ). Turning ON a source switch and a sink
switch in opposite halves of the bridge forces the full supply
voltage less the switch drops across the motor winding.
While the bridge remains in this state, the winding current in-
creases exponentially towards a limit dictated by the supply
voltage, the switch drops, and the winding resistance. Sub-
sequently turning OFF the sink switch causes a voltage tran-
sient that forward biases the body diode of the other source
switch. The diode clamps the transient at one diode drop
above the supply voltage and provides an alternative current
path. While the bridge remains in this state, it essentially
shorts the winding and the winding current recirculates and
decays exponentially towards zero. During a change in the
direction of the winding current, both the switches and the
body diodes provide a decay path for the initial winding cur-
rent (Figure 3 ).
DS011878-10
FIGURE 2. The DMOS H-Bridge
DS011878-11
DS011878-12
DS011878-13
FIGURE 3. Decay Paths for Initial Winding Current During a Change in the Direction of the Winding Current
7 www.national.com
7페이지 | |||
구 성 | 총 18 페이지수 | ||
다운로드 | [ LMD18245.PDF 데이터시트 ] |
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부품번호 | 상세설명 및 기능 | 제조사 |
LMD18245 | LMD18245 3A 55V DMOS Full-Bridge Motor Driver (Rev. E) | Texas Instruments |
LMD18245 | 3A / 55V DMOS Full-Bridge Motor Driver | National Semiconductor |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |