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

Abstract

This application note describes the optimized layout guide for the BQ257XX family of buck-boost charger solutions. BQ257XX family includes BQ2570X, BQ2571X, BQ2572X, BQ2573X. These products are synchronous NVDC buck-boost battery charge controller, offering a low component counts, high efficiency solution for space constrained, 1s~4s battery charging applications. In order for the chargers to perform optimally, certain layout rules should be followed. The rule of utilizing a good layout is to minimize the PCB trace inductance in the high di/dt current paths, to limit capacitive coupling from high dv/dt nodes onto other traces, and to ensure proper GND connections. By following the rules, designer will be able to achieve the best charger operation including low EMI, high accuracy, high efficiency, low temperature operation.