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参数资料
| 型号： | A8904SLP-T |
| 元件分类： | 运动控制电子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, 1.4 A, PDSO28 |
| 封装： | 1.20 MM HEIGHT, LEAD FREE, TSSOP-28 |
| 文件页数： | 3/18页 |
| 文件大小： | 736K |
| 代理商： | A8904SLP-T |
3-Phase Brushless DC Motor Controller/Driver
with Back EMF Sensing
A8904
11
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
After the watchdog capacitor CWD charges to the VTL threshold,
and if the correct polarity of back-EMF signal is detected, the
back-EMF detection circuit discharges CWD to zero volts (see
waveform above) and the circuit is ready to detect the next back-
EMF zero crossing.
If the correct polarity of back-EMF is not detected between
the blanking period, tBLANK, and the watchdog period, tWD,
then the back-EMF detection circuit does not allow the watch-
dog capacitor CWD to be discharged and the watchdog circuit
commutates the outputs to the next sequencer state (see wave-
form above). This mode of operation continues until a suitable
back-EMF signal is detected. This function is useful in prevent-
ing excessive reverse rotation, and helps in resynchronising (or
starting) with a moving spindle.
The duration of the watchdog-triggered commutation is
determined by:
tWD = VTH x CWD / ICWD
where ICWD = normal charge current.
Speed control
. The actual speed of the motor is measured
by either internally sensing the back-EMFs or by an external
scheme via the SECTOR DATA terminal. A TACH signal is
produced from these signals, which is then compared against the
desired speed, which is programmed into a 14-bit counter (see
diagram and waveforms below - assumes internal scheme used).
The resulting error signal, ERROR, is then used to charge or
discharge the FILTER terminal capacitor depending on whether
the motor is running too slow or too fast. The FILTER terminal
voltage is used to linearly drive the low-side MOSFETs to match
the desired speed.
Each back-EMF signal detected causes the state of the
FCOM signal to change. The number of FCOM transitions per
mechanical revolution is equal to the number of poles times 3.
For example, with a 4-pole motor (as shown on next page), the
number of FCOM transitions will equal 12 per mechanical revo-
lution. The number of poles are programmed via serial port bits
D20 and D21. There are six electrical states per electrical revolu-
tion, therefore, for this example, there are 12 commutations or
two electrical revolutions per mechanical revolution.
The TACH signal changes state once per mechanical revolu-
tion and as well as providing information on the actual motor
speed is also used to trigger the REF counter which contains
the information on the desired motor speed. Alternatively an
external TACH signal can be used, an explanation of which is
presented in the Sector Mode Section.
The duration of REF is set by programming the counter to
count the desired number of OSCILLATOR cycles, according to
the following:
total count = 60 x fOSC / desired motor speed (rpm)
where the total count (number of oscillator cycles) is equal to the
sum of the count numbers selected through bits D5 to D18 in the
serial port and fOSC corresponds to the OSCILLATOR frequency.
Functional Description (cont’d)
Watchdog-triggered commutation
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相关代理商/技术参数 |
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| A8904SLPTR | 功能描述:IC CTRLR/DRVR DC MOTOR 28TSSOP 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 |
| A8904SLPTR-T | 功能描述:IC CTRLR/DRVR DC MOTOR 28TSSOP 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 |
| A8905CLB | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH BACK-EMF SENSING |
| A8906CLB | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:BIDIRECTIONAL 3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH BACK-EMF SENSING |
| A8909CLB | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:3-PHASE BRUSHLESS DC MOTOR CONTROLLER/DRIVER WITH BACK-EMF SENSING AND POWER DMOS OUTPUTS |
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