SLVAFT1 September   2024 TPS92633-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2TPS92633-Q1 Design Considerations
    1. 2.1 Setting the Output Current
    2. 2.2 Single-LED-Short Diagnostic
      1. 2.2.1 Single-LED-Short Detection
      2. 2.2.2 Single-LED-Short Auto-Recovery
        1. 2.2.2.1 Implementation Results
  6. 3Summary
  7. 4References

2.1 Setting the Output Current

The TP92633-Q1 can set the output current I(OUTx_Tot) at each channel independently through regulating the voltage drop V(CS_REG) on the external high-side current-sense resistors R(SNSx). When the output current is in regulation, the current value can be calculated through Equation 1.

Equation 1. I O U T x _ T o t = V ( C S _ R E G ) R ( S N S x )

where

  • VCS_REG is variable according to Equation 2.
  • x = 1, 2 or 3 for output channel 1, 2, or 3.

The TPS92633-Q1 supports analog constant current for all three channels through adjusting the V(CS_REG). As depicted in Figure 2-1. The device outputs a constant current I(ICTRL) on the ICTRL pin and measures the voltage V(ICTRL) on the ICTRL pin to determine the V(CS_REG). The I(ICTRL) current is 10 times of the current I(IREF) on the IREF pin.

Internal Block Diagram of IREF, ICTRL and SLS_REF pins Figure 2-1 Internal Block Diagram of IREF, ICTRL and SLS_REF pins

The V(CS_REG) value can be changed following Equation 2

Equation 2. V ( C S _ R E G ) = V ( I R E F ) × R I C T R L × 25 R I R E F × 17

where

  • V(IREF) = 1.235V
  • R(IREF) is in kΩ unit
  • R(ICTRL) is in Ω unit

The desired output current of each channel can be calculated by Equation 3 which is a combination of Equation 1 and Equation 2

Equation 3. I O U T x _ T o t = V ( I R E F ) × R I C T R L × 75 R I R E F × R ( S N S x ) × 17  

where

  • V(IREF) = 1.235V
  • R(ICTRL) is in Ω unit
  • R(IREF) is in kΩ unit
  • R(SNSx) is in Ω unit

Seeing how the three channels are connected in parallel and then the total output current can be calculated by Equation 7.

Equation 4. I O U T _ P a r a l l e l _ T o t = I O U T 1 _ T o t + I O U T 2 _ T o t + I O U T 3 _ T o t

The previous calculation and the value selection of peripheral component parameters can be done with the assistance of TPS92633-Q1 External Component Calculation Tool.