SBOS697B September   2014  – July 2026 REF19

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  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 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Solder Heat Shift
    2. 7.2 Thermal Hysteresis
    3. 7.3 Noise Performance
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 VREF and VBIAS Tracking
      2. 8.3.2 Low Temperature Drift
      3. 8.3.3 Load Current
    4. 8.4 Device Functional Modes
  10. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Shunt Resistor
        2. 9.2.2.2 Differential Amplifier
        3. 9.2.2.3 Voltage Reference
        4. 9.2.2.4 Results
      3. 9.2.3 Application Curves
    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 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2 Detailed Design Procedure

Low-side current sensing is desirable because the common-mode voltage is near ground. Therefore, the current-sensing design is independent of the bus voltage, VBUS. When sensing bidirectional currents, use a differential amplifier with a reference pin. This procedure allows for the differentiation between positive and negative currents by biasing the output stage such that it can respond to negative input voltages. There are a variety of methods for supplying power (V+) and the reference voltage (VREF, or VBIAS) to the differential amplifier. For a low-drift design, use a monolithic reference that supplies both power and the reference voltage. Figure 9-2 shows the general circuit topology for a low-drift, low-side, bidirectional, current-sensing design. This topology is particularly useful when interfacing with an ADC; see Figure 9-1. Not only do VREF and VBIAS track over temperature, but the matching is much better than alternate topologies. For a more detailed version of the design procedure, see the Low-Drift Bidirectional Single-Supply Low-Side Current Sensing Design Guide.

REF19 Low-Drift, Low-side, Bidirectional, Current-Sensing Circuit TopologyFigure 9-2 Low-Drift, Low-side, Bidirectional, Current-Sensing Circuit Topology

The transfer function for the circuit given in Figure 9-2 is as shown in Equation 6:

Equation 6. V O U T = G × ( ± V S H U N T ) + V B I A S = G × ( ± I L O A D × R S H U N T ) + V B I A S