SBOS988A August   2019  – April 2020 DRV425-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Fluxgate Sensor Front-End
        1. 7.3.1.1 Fluxgate Sensor
        2. 7.3.1.2 Bandwidth
        3. 7.3.1.3 Differential Driver for the Internal Compensation Coil
        4. 7.3.1.4 Magnetic Field Range, Overrange Indicator, and Error Flag
      2. 7.3.2 Shunt-Sense Amplifier
      3. 7.3.3 Voltage Reference
      4. 7.3.4 Low-Power Operation
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Linear Position Sensing
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Current Sensing in Busbars
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Decoupling
    2. 9.2 Power-On Start-Up and Brownout
    3. 9.3 Power Dissipation
      1. 9.3.1 Thermal Pad
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

9.2 Power-On Start-Up and Brownout

Power-on is detected when the supply voltage exceeds 2.4 V at the VDD pin. At this point, the DRV425-Q1 initiates the following start-up sequence:

  1. Digital logic starts up and waits for 26 μs for the supply to settle.
  2. The fluxgate sensor powers up.
  3. The compensation loop is active 70 μs after the supply voltage exceeds 2.4 V.

During this startup sequence, the DRV1 and DRV2 outputs are pulled low to prevent undesired signals on the compensation coil and the ERROR pin is asserted low.

The DRV425-Q1 tests for low supply voltages with a brownout-voltage level of 2.4 V. Use a power-supply source capable of supporting large current pulses driven by the DRV425-Q1, and low-ESR bypass capacitors for a stable supply voltage in the system. A supply drop to less than 2.4 V that lasts longer than 20 μs generates a power-on reset; the device ignores shorter voltage drops. A voltage drop on the VDD pin to below 1.8 V immediately initiates a power-on reset. After the power supply returns to 2.4 V, the device initiates a start-up cycle.