- 您现在的位置：买卖IC网 > PDF目录223292 > A8904SLP-T BRUSHLESS DC MOTOR CONTROLLER, 1.4 A, PDSO28 PDF资料下载
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： | 2/18页 |
| 文件大小： | 736K |
| 代理商： | A8904SLP-T |
3-Phase Brushless DC Motor Controller/Driver
with Back EMF Sensing
A8904
10
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
(output crossing through centertap). If the correct polarity of
back-EMF is not detected, a watchdog circuit commutates the
output until the correct back-EMF is detected. Correct back-
EMF sensing is indicated by the FCOM signal, which toggles
every time the back-EMF completes a zero crossing (see wave-
forms below). FCOM is available at the DATA OUT terminal.
True back-EMF zero crossings are used by the adaptive
commutation delay circuit to advance the state sequencer (com-
mutate) at the proper time to synchronously run the motor. See
next section.
Adaptive commutation delay.
The adaptive commuta-
tion delay circuit uses the back-EMF zero-crossing indicator
signal (FCOM) to determine an optimal commutation time for
efcient synchronous switching of the output drivers. When the
FCOM signal changes state, one of the delay capacitors (CD1
or CD2) is discharged at approximately twice the rate of the
charging current. When the capacitor reaches the 2.5 V thresh-
old, a commutation occurs. During this discharge period, the
other delay capacitor is being charged in anticipation of the next
FCOM state change. In addition, there is an interruption to the
charging, which is set by the blanking duration (see waveform
below, VCWD, and next section). This additional charging delay
causes the commutation to occur at slightly less than 50% of
the FCOM on or off duration, to compensate for delays caused
by winding inductance. The typical delta voltage change during
normal operation in the commutation capacitors (CD1 & CD2),
will range between
1.5 V and 2.0 V. The commutation capacitor values can be deter-
mined from:
CDX = ICD x t / VCD
where VCD = 1.5 V, ICD = 20 μA, and t = (60/rpm)/(#motor poles
x 3), duration of each state.
Functional Description (cont’d)
To avoid the capacitors charging to the supply rail, the value
selected should provide adequate margin, taking into account the
effects of capacitor tolerance, charging current, etc.
Blanking and watchdog timing functions.
The blank-
ing and watchdog timing functions are derived from one timing
capacitor CWD .
During normal commutation, at the beginning of each new
sequencer state, a blanking signal is created until the watchdog
capacitor CWD is charged to the threshold VTL (see waveforms
below). This blanking signal prohibits the back-EMF compara-
tors from tripping due to the discharging of inductive energy and
voltage settling transients during sequence state transitions. The
duration of this blanking signal depends on the size of the CWD
capacitor and the programmed charge current, ICWD (via D26-
27). This blanking pulse also interrupts the commutation delay
capacitors CD1 and CD2 from charging (see previous section).
The ability to select the minimum charge current for CWD
is particularly useful during start-up, where the duration of the
diode recirculation current is highest. In applications where
high motor speeds are experienced, the charge current can be
increased so that the blanking period does not encroach signi-
cantly into the period of each sequencer state and does not cause
unbalance in the commutation points.
It is recommended to select the value of CWD in the actual
application circuit with the A8904 put into step mode. CST
should be reselected (only for this test), to be between 4.7 μF
and 10 μF, so that the motor comes to rest between steps and the
maximum diode conduction time can be measured. The value of
CWD can be determined as:
CWD = ICWD x td / VTL
where td = measured diode conduction, ICWD = charge current at
start-up, and VTL = 250 mV.
相关PDF资料 |
PDF描述 |
|---|---|
| AA031P1-A2 | 28000 MHz - 32000 MHz RF/MICROWAVE WIDE BAND LOW POWER AMPLIFIER |
| AA10A-024L-120S | 1-OUTPUT 10 W DC-DC REG PWR SUPPLY MODULE |
| AA30A-048L-120D120L | 2-OUTPUT 30 W DC-DC REG PWR SUPPLY MODULE |
| AA1114/2MBC/CC | SINGLE COLOR LED, BLUE |
| AA1114/2EC/CC | SINGLE COLOR LED, HIGH EFFICIENCY RED |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
发布紧急采购，3分钟左右您将得到回复。