SNVA881 November   2019 LP87521-Q1 , LP87522-Q1 , LP87523-Q1 , LP87524-Q1 , LP87525-Q1 , LP87561-Q1 , LP87562-Q1 , LP87563-Q1 , LP87564-Q1 , LP87565-Q1

 

  1.   Stability Considerations for LP8756x-Q1 and LP8752x-Q1
    1.     Trademarks
    2. 1 Introduction
    3. 2 Stability Target
    4. 3 Use Cases
    5. 4 Measurements
      1. 4.1 Measurement Setup
      2. 4.2 Measurement Results
    6. 5 Simulations
      1. 5.1 Simulation Model
      2. 5.2 Simulation Results
    7. 6 Summary
    8. 7 References

3 Use Cases

General use cases for the LP875x-Q1 devices are listed in Table 1. The total output capacitance is the sum of the CLOCAL capacitance near the switcher and CPOL point of load (POL) capacitance. The maximum total output capacitance per phase is 500 µF, if the output voltage slew-rate is less than or equal to 1.9 mV/µs. Higher slew-rates have lower maximum capacitance limits. Refer to LP8756x-Q1 16-A Buck Converter With Integrated Switches or LP8752x-Q1 10-A Buck Converter With Integrated Switches datasheet for more information.

Table 1. Use cases for LP875x devices

VIN (V) Switching frequency (MHz) L (nH) CIN (µF/phase) VOUT (mV) CLOCAL (µF/phase) IOUT (A) CPOL (µF/phase)
3.3 2 470 10 860 22 3.0 22
44
91
5.0 22
44
91
3.3 1000 22
44
91
5.0 22
44
91
3.3 1800 22
44
91
5.0 22
44
91
5.0 3300 22
44
91

In addition to the 21 use cases listed in Table 1, the phase configuration has an effect on stability. Every use case is measured and simulated for every phase configuration from 1 to 4 phases, totaling 84 measurements and simulations.