ZHCSHA0C January   2018  – September 2018 DRV10974

PRODUCTION DATA.  

  1. 特性
  2. 应用
  3. 说明
    1.     应用原理图
  4. 修订历史记录
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Speed Input and Control
      2. 7.3.2 Motor Direction Change
      3. 7.3.3 Motor-Frequency Feedback (FG)
      4. 7.3.4 Lock Detection
        1. 7.3.4.1 Lock Kt Measure
        2. 7.3.4.2 Lock No Motor
        3. 7.3.4.3 Lock Open Loop Abnormal
        4. 7.3.4.4 Lock BEMF Abnormal
        5. 7.3.4.5 Lock Closed Loop Abnormal
        6. 7.3.4.6 Lock Speed Abnormal
      5. 7.3.5 Soft Current-Limit
      6. 7.3.6 Short-Circuit Current Protection
      7. 7.3.7 Overtemperature Protection
      8. 7.3.8 Undervoltage Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Spin-Up Settings
        1. 7.4.1.1 Motor Start
        2. 7.4.1.2 Initial Speed Detect
        3. 7.4.1.3 Align
      2. 7.4.2 Open-Loop Acceleration
      3. 7.4.3 Start-Up Current Sensing
      4. 7.4.4 Closed Loop
      5. 7.4.5 Control Advance Angle
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 第三方产品免责声明
    2. 11.2 接收文档更新通知
    3. 11.3 社区资源
    4. 11.4 商标
    5. 11.5 静电放电警告
    6. 11.6 术语表
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

Soft Current-Limit

The current-limit function provides active protection for preventing damage as a result of high current. The soft current-limit does not use direct-current measurement for protection, but rather, uses the measured motor resistance (Rm) and motor velocity constant (Kt) to limit the voltage applied to the phase (U) such that the current does not exceed the limit value (I(LIMIT)). The soft current-limit scheme is shown in Figure 14 based on the calculation in Equation 4.

The soft current-limit is only active when in normal closed-loop mode and does not result in a fault condition nor does it result in the motor being stopped. The soft current-limit is typically useful for limiting the current that results from heavy loading during motor acceleration. The I(LIMIT) current is configured by an external resistor (R(CS)) as shown in Table 1.

DRV10974 figure_current_limit.gifFigure 14. Current Limit

Use Equation 4 to calculate the I(LIMIT) value.

Equation 4. DRV10974 eq_03_ulimit_slvsdn2.gif

Table 1 can be used to determine the I(LIMIT) value.

Table 1. Soft Current-Limit Selections

R(CS) [kΩ](1) I(LIMIT) [mA]
7.32 200
16.2 400
25.5 600
38.3 800
54.9 1000
80.6 1200
115 1400
182 1600 (1500 during align)
All resistors are ±1 %.

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NOTE

The soft current-limit is not correct if the motor is out of phase with the commutation control logic (locked rotor). The soft current-limit is not effective under this condition.