SBOSAF3A November   2023  – June 2024 TMCS1126

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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 Insulation Specifications
    6. 6.6 Electrical Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Accuracy Parameters
      1. 7.1.1 Sensitivity Error
      2. 7.1.2 Offset Error and Offset Error Drift
      3. 7.1.3 Nonlinearity Error
      4. 7.1.4 Power Supply Rejection Ratio
      5. 7.1.5 Common-Mode Rejection Ratio
      6. 7.1.6 External Magnetic Field Errors
    2. 7.2 Transient Response Parameters
      1. 7.2.1 CMTI, Common-Mode Transient Immunity
    3. 7.3 Safe Operating Area
      1. 7.3.1 Continuous DC or Sinusoidal AC Current
      2. 7.3.2 Repetitive Pulsed Current SOA
      3. 7.3.3 Single Event Current Capability
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Current Input
      2. 8.3.2 Ambient Field Rejection
      3. 8.3.3 High-Precision Signal Chain
        1. 8.3.3.1 Temperature Stability
        2. 8.3.3.2 Lifetime and Environmental Stability
      4. 8.3.4 Internal Reference Voltage
      5. 8.3.5 Current-Sensing Measurable Ranges
      6. 8.3.6 Overcurrent Detection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down Behavior
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Total Error Calculation Examples
        1. 9.1.1.1 Room-Temperature Error Calculations
        2. 9.1.1.2 Full-Temperature Range Error Calculations
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Nomenclature
    2. 10.2 Device Support
      1. 10.2.1 Development Support
    3. 10.3 Documentation Support
      1. 10.3.1 Related Documentation
    4. 10.4 Receiving Notification of Documentation Updates
    5. 10.5 Support Resources
    6. 10.6 Trademarks
    7. 10.7 Electrostatic Discharge Caution
    8. 10.8 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.6 Overcurrent Detection

In addition to a fast precision analog signal response, the TMCS1126 also offers a fast digital overcurrent response. The Overcurrent Detection (OCD) circuit provides a comparator output that can be used to trigger a warning or system shutdown to prevent damage from excessive current flow caused by short circuits, motor stalls, or other system conditions. This fast digital response can be configured on both bidirectional and unidirectional devices to trip anywhere between half and over twice the analog measurement range. When set up to trigger outside the analog measurement range, this fast digital overcurrent output OC along with the precision analog output VOUT allows the user to optimize control-loop dynamic range.

The desired overcurrent threshold IOC is set by applying an external voltage VOC to the VOC pin according to Equation 21.

Equation 21. V O C = S × I O C 2.5

where

  • S is the device sensitivity in mV/A.
  • IOC is the desired overcurrent threshold.
  • VOC is the voltage applied that sets the overcurrent threshold.

A digital-to-analog converter (DAC) can be used to set the desired overcurrent threshold IOC, or a simple external resistor divider circuit can be used as shown in Figure 8-5. When using a resistor divider, R2 must be less than 10kΩ to mitigate the impact of the VOC input impedance on overcurrent threshold accuracy.

TMCS1126 User Configurable Overcurrent Threshold Using Power Supply Voltage Figure 8-5 User Configurable Overcurrent Threshold Using Power Supply Voltage

Higher overcurrent threshold accuracy can be achieved on the bidirectional TMCS1126Axx and TMCS1126Bxx devices by using the zero current output reference voltage VREF as shown in Figure 8-6.

TMCS1126 User Configurable Overcurrent Threshold Using Zero Current Output Reference Voltage Figure 8-6 User Configurable Overcurrent Threshold Using Zero Current Output Reference Voltage

For example, to set the desired overcurrent threshold to IOC = ±50A on the bidirectional TMCS1126A3A or TMCS1126B3A devices, or to IOC = 50A on the unidirectional TMCS1126C3A device, size the resistors R1 and R2 to apply a voltage VOC = 1.5V to the VOC pin according to Equation 21.

with

  • TMCS1126A3A, TMCS1126B3A and TMCS1126C3A device sensitivity, S = 75mV/A.
  • Desired overcurrent threshold, IOC = 50A.
  • Applied overcurrent threshold voltage VOC = 1.5V.

Figure 8-7 shows the overcurrent digital output OC response as active-low. When the input current exceeds ±IOC on a bidirectional device, the fast OC pin is pulled low. The input current must return to within ±IOC by more than a hysteresis current IHys before the OC pin resets back to the normal high-state.

TMCS1126 Overcurrent Detection Diagram Figure 8-7 Overcurrent Detection Diagram