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参数资料
| 型号： | A3987SLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 9/13页 |
| 文件大小： | 0K |
| 描述： | IC DRIVER MICROSTEPPING 24-TSSOP |
| 产品培训模块： | A3987 DMOS Microstepping |
| 标准包装： | 1 |
| 应用： | 步进电机驱动器 |
| 输出数： | 1 |
| 电流 - 输出： | ±1.5A |
| 电压 - 负载： | 8 V ~ 50 V |
| 电源电压： | 3 V ~ 5.5 V |
| 工作温度： | -20°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 24-TSSOP 裸露焊盘 |
| 包装： | 标准包装 |
| 产品目录页面： | 1141 (CN2011-ZH PDF) |
| 其它名称： | 620-1171-6 |
A3987
DMOS Microstepping Driver with Translator
Functional Description
Device Operation The A3987 is a complete microstepping
motor driver with built-in translator for easy operation with
a minimum of control lines. The A3987 is designed to oper-
ate bipolar stepper motors in full, half, quarter, and sixteenth
step modes. The full bridges on the dual outputs are composed
entirely of N-channel DMOS FETS, and the full bridge currents
are regulated by fixed off-time, pulse width modulated (PWM)
control circuitry. For each full bridge, the individual step currents
are set by the combination of: a common external reference volt-
age, V REF ; an external current sense resistor, R SENSE x ; and the
output voltage of an internal DAC that is controlled by the output
of the translator.
At power-up or reset, the translator sets the DACs and phase
current polarity to the initial home state (see figures 2 through
5 for home state conditions), and also sets the current regulator
for both output phases to mixed decay mode. When a command
signal occurs on the STEP input, the translator automatically
sequences the DACs to the next level (see table 2 for the current
level sequence) and current polarity. The microstep resolution
is set by inputs MS1 and MS2 (see in table 1 for state settings).
If logic inputs are pulled up to VDD, it is good practice to use a
high value pull-up resistor in order to limit current to the logic
inputs should an overvoltage event occur. If the new DAC output
level is lower than the previous level, then the decay mode for
that full bridge will be set to mixed decay. If the new DAC level
is higher or equal to the previous level, then the decay mode for
that full bridge will be slow decay. This automatic current decay
selection improves microstepping performance by reducing the
distortion of the current waveform due to the motor BEMF.
Low-Power Mode Select (SLEEP/RESET) An active-
low control input used to minimize power consumption when the
A3987 is not in use. This disables much of the internal circuitry
including the output FETs and internal regulator. A logic high
allows normal device operation and power-up in the home state.
When coming out of sleep mode, a 1 ms delay is required before
issuing a STEP command, to allow the internal regulator to
stabilize. The outputs can also be reset to the home state without
entering sleep mode. To do so, pulse this input low for a duration
between t RP (min) and t RP (max).
Step Input (STEP) A low-to-high transition on the STEP
input sequences the translator and advances the motor one incre-
ment. The translator controls the input to the DACs and the direc-
tion of current flow in each winding. The size of the increment is
determined by the state of inputs MS1 and MS2.
Microstep Select (MS1 and MS2) Inputs MS1 and MS2
select the microstepping format (see table 1 for state settings).
Changes to these inputs do not take effect until the next STEP
command. It is good practice to use a pull-up resistor to VDD in
order to limit input current should an external overvoltage occur.
A minimum of 5 k Ω is recommended.
Direction Input (DIR) The state of the DIR input determines
the direction of rotation of the motor. A logic change on the DIR
pin will not take effect until the next STEP command is issued.
Internal PWM Current Control Each full bridge is
controlled by a fixed off-time PWM current control circuit that
limits the load current to a desired value (I TRIP ). Initially, a
diagonal pair of source and sink FETs are enabled and current
flows through the motor winding and the corresponding current
sense resistor, R SENSE x . When the voltage across R SENSE equals
the DAC output voltage, the current sense comparator resets the
PWM latch, which turns off the source drivers (in slow decay
mode) or the sink and source drivers (in fast or mixed decay
modes).
The maximum value of current limiting is set by the selection of
R SENSE and the voltage at the REF input, with a transconductance
function approximated by:
I TRIP (max) = V REF / (8 × R SENSE ) .
The DAC output reduces the V REF output to the current sense
comparator in precise steps:
I TRIP = (% I TRIP (max) / 100) × I TRIP (max) ,
(see table 2 for % I TRIP (max) at each step).
Note: It is critical that the absolute maximum voltage rating
(0.5 V) on the SENSE pins is not exceeded.
Fixed Off-Time The internal PWM current control circuitry
uses a 4 MHz master oscillator to control the duration of time that
the drivers remain off. The fixed off-time, t OFF , is determined by
the selection of an external resistor connected from the ROSC
timing terminal to VDD. If the ROSC terminal is tied directly to
GND, t OFF defaults to 25 μ s. The off-time is approximated by:
t OFF ≈ R OSC / (1.981 × 10 9 )
Blanking This function blanks the output of the current sense
comparator when the outputs are switched by the internal current
control circuitry. The comparator output is blanked to prevent
false overcurrent detections due to reverse recovery currents of
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
9
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相关代理商/技术参数 |
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|---|---|
| A3987SLPTR-T | 制造商:Allegro MicroSystems 功能描述:IC MOTOR DRIVER DMOS 1.5A TSSOP-24 |
| A3988 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Quad DMOS Full Bridge PWM Motor Driver |
| A3988_11 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:The A3988 is a quad DMOS full-bridge driver capable of driving up to two stepper motors or four DC motors. |
| A3988SEV-T | 制造商:Allegro MicroSystems 功能描述:DMOS Full Bridge PWM Motor Driver 36-Pin QFN EP Tube 制造商:Allegro MicroSystems 功能描述:Motor Driver IC |
| A3988SEVTR-1-T | 功能描述:MOTOR DRIVER 36QFN 制造商:allegro microsystems, llc 系列:- 零件状态:有效 标准包装:1,500 |
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