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| 型号： | A3979SLPTR |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 9/15页 |
| 文件大小： | 0K |
| 描述： | IC DRIVER MICROSTEPPING 28-TSSOP |
| 标准包装： | 4,000 |
| 应用： | 步进电机驱动器 |
| 输出数： | 1 |
| 电流 - 输出： | ±2.5A |
| 电压 - 负载： | 8 V ~ 35 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： | 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： | 带卷 (TR) |
A3979
DMOS Microstepping Driver with Translator
Synchronous Rectification. When a PWM off-
cycle is triggered by an internal fixed–off-time cycle, load
current recirculates according to the decay mode selected
by the control logic. The A3979 synchronous rectification
feature turns on the appropriate MOSFETs during the decay
of the current, and effectively shorts out the body diodes
with the low R DS(On) driver. This reduces power dissipation
significantly and eliminates the need for external Schottky
diodes for most applications. The synchronous rectification
can be set to either Active mode or Disabled mode:
? Active Mode . When the SR input is logic low, Active
mode is enabled and synchronous rectification can occur.
This mode prevents reversal of the load current by turning
off synchronous rectification when a zero current level is
detected. This prevents the motor winding from conduct-
ing in the reverse direction.
? Disabled Mode. When the SR input is logic high, syn-
chronous rectification is disabled. This mode is typi-
cally used when external diodes are required to transfer
power dissipation from the A3979 package to the external
diodes.
Applications Information
Layout. The printed circuit board on which the device is
mounted should have a heavy ground plane. For optimum
electrical and thermal performance, the A3979 should be
soldered directly onto the board.
The load supply terminals, VBB x , should be decoupled with
an electrolytic capacitor (>47 μ F is recommended), placed
as close to the device as possible.
To avoid problems due to capacitive coupling of the high
dv / dt switching transients, route the bridge-output traces
away from the sensitive logic-input traces.
Always drive the logic inputs with a low source impedance
to increase noise immunity.
Grounding. The AGND (analog ground) terminal and the
PGND (power ground) terminal must be connected together
externally.
All ground lines should be connected together and be as
short as possible. A star ground system, centered under the
device, is an optimum design.
The copper ground plane located under the exposed thermal
pad is typically used as the star ground.
Current Sensing. To minimize inaccuracies caused by
ground-trace IR drops in sensing the output current level,
the current-sense resistors, R S x , should have an independent
ground return to the star ground of the device. This path
should be as short as possible.
For low-value sense resistors, the IR drops in the printed cir-
cuit board sense resistor traces can be significant and should
be taken into account.
The use of sockets should be avoided as they can introduce
variation in R S x due to their contact resistance.
Allegro MicroSystems recommends a value of R S given by
R S = 0.5/I TRIP max
Thermal Protection. This internal circuitry turns off
all drivers when the junction temperature reaches 165°C,
typical. It is intended only to protect the device from failures
due to excessive junction temperatures and should not imply
that output short circuits are permitted. Thermal shutdown
has a hysteresis of approximately 15°C.
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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| A3979SLPTR-T | 功能描述:IC DRIVER MICROSTEPPING 28-TSSOP 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:步进电机驱动器，1-2 相，2 相 评估套件:- 输出数:1 电流 - 输出:800mA 电压 - 负载:10 V ~ 28 V 电源电压:4.75 V ~ 5.25 V 工作温度:-20°C ~ 90°C 安装类型:表面贴装 封装/外壳:28-SOP + 2 翼片裸露焊盘 供应商设备封装:28-HSOPHC（15.2x7.9） 包装:剪切带 (CT) 其它名称:869-1268-1 |
| A397A | 制造商:n/a 功能描述:Power Semiconductor |
| A397B | 制造商:Powerex Power Semiconductors 功能描述:DIODE FAST REC 200V 400A |
| A397C | 制造商:n/a 功能描述:Power Semiconductor |
| A397D | 制造商:n/a 功能描述:Power Semiconductor 制造商:Powerex Power Semiconductors 功能描述:DIODE FAST REC 400V 400A |
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