SLUAAU1 January   2024 BQ25700A , BQ25708 , BQ25710 , BQ25713 , BQ25720 , BQ25723 , BQ25730 , BQ25731

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 BQ25710 EVM Circuit
  5. 2Layout Guidelines
    1. 2.1 PCB Stack-Up (4 Layers)
    2. 2.2 Identifying Critical Circuit Paths
    3. 2.3 Input and Output Loop Placements Considering Noise, Efficiency, and Thermal Performance
    4. 2.4 Kelvin Sensing Circuit for Current Sense to Achieve High Accuracy
    5. 2.5 Small Capacitors Placements Considering Noise
    6. 2.6 Separating AGND and PGND
  6. 3References

1 Introduction

Buck-boost charger has 5 switches and one inductor. The proper layout design is the key to achieve the stable operation, good thermal and low EMI performance. But there are many layout challenges for circuit designers. A poor layout can result in low efficiency, reduced charging capability, reduced measurement accuracy, or even unstable operation due to noise interference. To overcome the challenges, TI BQ257XX EVM is a good starting point for a custom layout. There can be alternative methods however, this layout is proven and most likely provides the best operation of the device due to the optimization of PCB trace inductance and the suggested grounding method. Figure 1-1 shows the BQ25710 EVM circuit as an example for the layout guide in this application note.