SLVAFP0 December   2023 LMR51610

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Specifications
    1. 2.1 Input Voltage Range
    2. 2.2 Output Current Range
  6. 3External Component Selection
    1. 3.1 Duty Cycle Calculation
    2. 3.2 Output Voltage Calculation
    3. 3.3 Inductor Selection
    4. 3.4 Input and Output Capacitor
    5. 3.5 Enable Level Shift
    6. 3.6 Output Clamp Diode
  7. 4Evaluation Results
    1. 4.1 Typical Performance
    2. 4.2 Loop Response Bench Verification
  8. 5Conclusion
  9. 6References
  10. 7LMR50410 Design Example
    1. 7.1 LMR50410 Output Current Range
    2. 7.2 LMR50410 Efficiency

2.2 Output Current Range

The output current capability in the IBB topology is less than the buck configuration. This is because the inductor average current is different from Buck technology, that in buck circuit inductor current is the same as Iout current. As a result, refer to the following equations to choose the device to cover inductor max current in IBB use.

In Equation 4, where IOUT is the maximum output current of the device (IOUT = 1A). The inverting power supply output current limit is calculated as shown in Figure 7-2.Where D is duty cycle of IBB , and take consider the η= 80% for efficiency in Equation 3.

Equation 3. D=VoutVout-Vin*η
Equation 4. IOUT(IBB)=IOUT_Buck×(1-D)
Table 2-1 Maximum Output Current Calculations for LMR51610
VO (V) VIN (V)

η

D

 IOUT (A)
-12

24

0.8

0.38

0.61

-5

24

0.8

0.20

0.79

-15

24

0.8

0.43

0.56
GUID-20230915-SS0I-4PQG-HVGF-N98VTRMR2J37-low.svgFigure 2-1 Maximum Output Current of the Inverting Power Supply