Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Current Shunt Monitors


Published on

Introduction of the current sensing technology and featured current shunt monitors from Texas Instruments

Published in: Technology, Business
  • Be the first to comment

Current Shunt Monitors

  1. 1. Current Shunt Monitors <ul><li>Source: T EXAS I NSTRUMENTS </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>This training module introduces the current sensing technology. We also discuss the featured current shunt monitors from TI. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>Basic current sensing technology </li></ul></ul><ul><ul><li>Analog current shunt monitors </li></ul></ul><ul><ul><li>Digital current shunt monitors </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>16 pages </li></ul></ul><ul><li>Duration </li></ul><ul><ul><li>15 Minutes </li></ul></ul>
  3. 3. What is a Current Sensor? <ul><li>Current sensor: electronic circuits that monitor the current flow by measuring the voltage drop across a resistor placed in the current path. </li></ul>
  4. 4. Low Side Current Sensing <ul><li>Advantages: </li></ul><ul><li>Straightforward, easy, and rarely requires more than an op-amp to implement </li></ul><ul><li>Inexpensive and precise </li></ul><ul><li>Disadvantages: </li></ul><ul><li>Adds undesirable resistance in the ground path </li></ul><ul><li>May require an additional wire to the load that could otherwise be omitted </li></ul>
  5. 5. High Side Current Sensing <ul><li>Advantages: </li></ul><ul><li>Current sensor connected directly to the power source and can detect any downstream failure and trigger appropriate corrective action </li></ul><ul><li>No extra ground disturbance that comes with a low side current sensing design </li></ul><ul><li>Disadvantages: </li></ul><ul><li>Requires very careful resistor matching in order to obtain an acceptable common-mode rejection ratio (CMMR). </li></ul><ul><li>Must withstand very high, and often dynamic, common-mode voltages. </li></ul>
  6. 6. Current Shunt Monitors <ul><li>Integrating high side current shunt measurement capabilities into a single IC provides a vast amount of added benefits </li></ul>
  7. 7. INA21x Current Shunt Monitors <ul><li>FEATURES </li></ul><ul><li>Bi-directional current monitoring </li></ul><ul><li>Wide common-mode range: –0.3V to 26V </li></ul><ul><li>Offset voltage: ±35mV </li></ul><ul><li>Accuracy </li></ul><ul><ul><li>±1% Gain error (max over temperature) </li></ul></ul><ul><ul><li>0.5mV/°C Offset drift (max) </li></ul></ul><ul><ul><li>10ppm/°C Gain drift (max) </li></ul></ul><ul><li>Quiescent current: 100mA (max) </li></ul>
  8. 8. Basic Connections Bidirectional operation Unidirectional operation
  9. 9. Input Filtering GainError% = 100 - [100 {R 3 /(R 3 + R FILT )}]
  10. 10. Shutdown Control
  11. 11. Effects of Impedance on the REF Input
  12. 12. Transient Protection Using a Single Transzorb and Input Clamps Using Dual Zener Diodes
  13. 13. Digital Current Shunt Monitor <ul><li>Features </li></ul><ul><li>Senses bus voltages from 0V to +26V </li></ul><ul><li>Reports current, voltage, and power </li></ul><ul><li>16 programmable addresses </li></ul><ul><li>High accuracy: 1% (max) </li></ul><ul><li>Filtering options </li></ul><ul><li>Calibration registers </li></ul>
  14. 14. Bus Overview <ul><li>The master must address slave devices via a slave address byte. </li></ul><ul><li>Two address pins, A0 and A1. </li></ul><ul><li>Accessing a particular register on the INA219 is accomplished by writing the appropriate value to the register pointer. </li></ul><ul><li>When reading from the INA219, the last value stored in the register pointer by a write operation determines which register is read during a read operation. </li></ul><ul><li>To change the register pointer for a read operation, a new value must be written to the register pointer. </li></ul>Bus
  15. 15. ADC Functions Configuration Register 00h (Read/Write)
  16. 16. Programming Power Measurement Engine <ul><li>Establish the parameters V BUS_MAX , V SHUNT_MAX and R SHUNT </li></ul><ul><li>Determine the maximum possible current </li></ul><ul><li>Choose the desired maximum current value </li></ul><ul><li>Calculate the possible range of current LSBs </li></ul><ul><li>Compute the Calibration Register value </li></ul><ul><li>Calculate the Power LSB </li></ul><ul><li>Compute the maximum current and shunt voltage values </li></ul><ul><li>Compute the maximum power </li></ul><ul><li>Compute corrected full-scale calibration value based on measured current </li></ul>Max_Expected_I ≤ I MAX Power_LSB = 20 Current_LSB Max_Current = Current_LSB x 32767 MaximumPower = Max_Current_Before_Overflow x V BUS_MAX
  17. 17. Additional Resource <ul><li>For ordering the current shunt monitors, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For additional inquires contact our technical service hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li> </li></ul></ul>