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参数资料
| 型号： | A3981KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 9/43页 |
| 文件大小： | 0K |
| 描述： | IC MOTOR DVR MICROSTEP 28-TSSOP |
| 标准包装： | 1 |
| 系列： | * |
| 应用： | * |
| 输出数： | * |
| 电流 - 输出： | * |
| 电压 - 负载： | * |
| 电源电压： | * |
| 工作温度： | * |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
| 包装： | 标准包装 |
| 其它名称： | 620-1458-6 |
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A3981
Automotive, Programmable Stepper Driver
impedance allowing multiple SDI slaves to have common SDI,
SCK, and SDO connections.
DIAG Diagnostic output. Function selected via the serial inter-
face, setting Configuration Register 1. Default is Fault output.
OSC With bit 13 in Configuration Register 1 set to 0, either con-
nect this pin to AGND to use the internal oscillator running at the
default frequency of 4 MHz, or connect a resistor to VDD to set
the internal oscillator frequency. ( The approximate frequency is
calculated from:
f OSC = 10 000 / (48 R OSC – 20)
where f OSC is the internal oscillator frequency in MHz, and R OSC
is the value, in k Ω of the resistor between OSC and VDD.)
If bit 13 in Configuration Register 1 is set to 1, then OSC is the
input for an external system clock, which must have a frequency
between 3 and 5 MHz. In this mode a watchdog is provided to
detect loss of the system clock. If the OSC pin remains high or
low for more than the watchdog time, t WD , 1 μ s typical, then the
Fault Register flag (bit 15 in the diagnostic registers) is set and
the outputs are disabled until the clock restarts.
Driving a Stepper Motor
A two-phase stepper motor is made to rotate by sequencing
the relative currents in each phase. In its simplest form, each
phase is simply fully energized in turn by applying a voltage to
the winding. For more precise control of the motor torque over
temperature and voltage ranges, current control is required. For
efficiency this is usually accomplished using pulse width modula-
tion (PWM) techniques. In addition current control also allows
the relative current in each phase to be controlled, providing more
precise control over the motor movement and hence improve-
ments in torque ripple and mechanical noise. Further details of
stepper motor control are provided in Appendix A.
For bipolar stepper motors the current direction is significant,
so the voltage applied to each phase must be reversible. This
requires the use of a full bridge (also known as an H-bridge)
which can switch each phase connection to supply or to ground.
Phase Current Control
In the A3981, current to each phase of the two-phase bipolar
stepper motor is controlled through a low impedance N-channel
DMOS full bridge. This allows efficient and precise control of
the phase current using PWM switching. The full-bridge con-
figuration provides full control over the current direction during
the PWM on-time, and over the current decay mode during the
PWM off-time. Due to the flexibility of the A3981 these control
techniques can be completely transparent to the user or can be
partially- or fully-programmed through the serial interface.
Each leg (high-side, low-side pair) of a bridge is protected from
shoot-through by a fixed dead time. This is the time between
switching off one FET and switching on the complementary FET.
Cross-conduction is prevented by lock-out logic in each driver pair.
The phase currents and in particular the relative phase currents
are defined in the Phase Current table (table 7). This table defines
the two phase currents at each microstep position. For each of the
two phases, the currents are measured using a sense resistor, R S ,
with voltage feedback to the respective SENSx pin. The target
current level is defined by the voltage from the digital-to-analog
converter (DAC) for that phase. The sense voltage is amplified by
a fixed gain and compared to the output of the DAC.
There are two types of maximum current : the absolute maximum,
I SMAX , the maximum possible current defined by the sense resis-
tor and the reference input; and the phase maximum, I PMAX , the
maximum current delivered to a motor phase.
The absolute maximum current, I SMAX , is defined as:
I SMAX = V REF / (16 × R S )
where V REF is the voltage at the REF pin, and R S is the sense
resistor value.
The phase maximum, I PMAX , is the 100% reference level for the
phase current table and may be a fraction of the absolute maxi-
mum current, I SMAX , depending on the value of the MXI0 and
MXI1 bits in Configuration Register 0.
For example:
? if R S = 180 m Ω and V REF = 2 V, then I SMAX = 694 mA
? if MXI1= 1 and MXI0 = 0, then I PMAX = 520 mA
The actual current delivered to each phase at each Step Angle
Number is determined by the value of I PMAX and the contents
of the Phase Current table. For each phase, the value in the table
is passed to the DAC, which uses I PMAX as the reference 100%
level (code 63) and reduces the current target depending on the
DAC code. The output from the DAC is used as the input to the
current comparators.
The current comparison is ignored at the start of the PWM
on-time for a duration referred to as the blank time . The blank
time is necessary to prevent any capacitive switching currents
from causing a peak current detection.
The PWM on-time starts at the beginning of each PWM period.
The current rises in the phase winding until the sense voltage
reaches the required current level. At this point the PWM off-time
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
相关PDF资料 |
PDF描述 |
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| A3982SLB-T | IC MOTOR DRIVER STEPPER 24-SOIC |
| A3983SLP-T | IC MICRO STEPPING DRIVER 24-TSSO |
| A3984SLP-T | IC MICRO STEPPING DRIVER 24-TSSO |
| A3986SLDTR-T | IC DRIVER MICROSTEPPING 38-TSSOP |
| A3987SLPTR-T | IC DRIVER MICROSTEPPING 24-TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| A3982 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:DMOS Stepper Motor Driver with Translator |
| A3982_13 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:DMOS Stepper Motor Driver with Translator |
| A3982SLB | 功能描述:IC MOTOR DRIVER STEPPER 24-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电机和风扇控制器，驱动器 系列:- 标准包装:1 系列:- 应用:直流电机驱动器，步进电机驱动器 评估套件:- 输出数:1 或 2 电流 - 输出:750mA 电压 - 负载:10 V ~ 40 V 电源电压:4.5 V ~ 5.5 V 工作温度:-20°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-BFSOP（0.295"，7.50mm 宽） 供应商设备封装:24-SOP 包装:Digi-Reel® 其它名称:MTS62C19A-HS105DKR |
| A3982SLB-T | 功能描述:IC MOTOR DRIVER STEPPER 24-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电机和风扇控制器，驱动器 系列:- 标准包装:1 系列:- 应用:直流电机驱动器，步进电机驱动器 评估套件:- 输出数:1 或 2 电流 - 输出:750mA 电压 - 负载:10 V ~ 40 V 电源电压:4.5 V ~ 5.5 V 工作温度:-20°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-BFSOP（0.295"，7.50mm 宽） 供应商设备封装:24-SOP 包装:Digi-Reel® 其它名称:MTS62C19A-HS105DKR |
| A3982SLB-T | 制造商:Allegro MicroSystems 功能描述:Motor Driver IC |
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