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参数资料
| 型号： | A3981KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 13/43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
next occurrence of: the next rising edge on the STEP input, the
RESETn input is pulsed low, or until the diagnostic registers
are reset by writing to one of the registers through the serial
interface. At the next STEP command or after a fault reset, the
Fault Register flag is cleared, the outputs are re-enabled, and the
voltage across the FET is resampled. Note that the diagnostic
registers are not cleared by the rising edge of the STEP input.
While the fault persists the A3981 will continue this cycle,
enabling the outputs for a short period then disabling the out-
puts. This allows the A3981 to handle a continuous short circuit
without damage. If, while stepping rapidly, a short circuit appears
and no action is taken, the repeated short circuit current pulses
will eventually cause the temperature of the A3981 to rise and an
overtemperature fault will occur.
Open Load Detection Open load conditions are detected
by monitoring the phase current when the phase DAC value
is greater than 31. The Open Load Current Threshold, I OL , is
defined by the OL0 and OL1 bits in the Run register as a percent-
age of the maximum (100%) phase current, I PMAX , defined in the
Phase Current table. The 100% level in the Phase Current table is
defined by the sense resistor value and the contents 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
? if OL1=0 and OL0=1, then I OL = 156 mA
The open load current monitor is only active after a blank
time from the start of a PWM cycle. An open load can only be
detected if the DAC value for the phase is greater than 31 and the
current has not exceeded the Open Load Current Threshold for
more than 15 PWM cycles.
The A3981 continues to drive the bridge outputs under an open
load condition and clears the Fault Register flag as soon as the
phase current exceeds the Open Load Current Threshold or the
DAC value is less than 32. The diagnostic registers retain the
open load fault bits, OLA and OLB, and will not be cleared until
RESETn is pulsed low or one of the diagnostic registers is written
through the serial interface.
Stall Detection A PWM monitor feature is included in the
A3981 to assist in determining the stall condition of the stepper
motor. A stalled motor condition is when the phase currents are
being sequenced to step the motor but the motor remains station-
ary. This can be due to a mechanical blockage such as an end stop
or it can be due to the step sequence exceeding the motor capabil-
ity for the attached load. Reliable stall detection in a simple step-
per driver is only possible by combining the PWM monitor with
a continuous step sequence at a sufficiently high step rate.
When a motor is stopped or moving slowly there is no back EMF
to impede the current in the phase windings. This allows the
current to rise to the limit quickly and the PWM current control
to activate. However, when a motor is running at speed the back
EMF, generated by the speed of the magnetic poles in the motor
passing the phase windings, acts against the supply voltage and
reduces the rise time of the phase current. Therefore the PWM
current control takes longer to activate. Assuming a constant step
rate, this results in fewer PWM cycles for each step of the motor.
The A3981 uses this difference to detect a motor changing from
continuous stepping to stalled. Two PWM counters, one for each
phase, accumulate the number of PWM cycles when the phase
current is stepped from zero to full current. At the end of each
phase current rise, the counter for that phase is compared to the
counter for the previous current rise, in the opposite phase. If the
difference is greater than the number in the PWM compare regis-
ter, then the ST bit in the diagnostic registers is set. In addition, if
the ST signal is selected as the output on the DIAG pin, then the
pin will go low.
This stall detection scheme assumes a number of factors:
? The motor must be stepping fast enough for the back EMF
to reduce the phase current slew rate. Stall detection reliability
improves as the current slew rate reduces.
? The motor is not being stepped in full step mode.
? The phase current table must conform to the 0% and ±100%
conditions at steps 0, 16, 32, and 48.
? The phase current profiles must be the same for both phases.
Although stall detection cannot be guaranteed using this detection
method, good stall detection reliability can be achieved by careful
selection of motor speed, count difference, and by conforming to
the above factors.
In addition to using the integrated features of the A3981, it is
also possible to perform stall detection by examining the PWM
on-time for a single phase using an external microcontroller. In
the A3981 the PWM-on signal for phase A can be selected as the
output on the DIAG pin, by using the serial interface.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
相关PDF资料 |
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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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