SLUAAG7 October   2021 BQ25720

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Type-C Power Delivery (PD) Connection
    2. 1.2 Type-C Battery Charging Topologies
    3. 1.3 BQ25720 Overview
  3. 2Design Considerations for Notebook Applications
    1. 2.1 Vmin Active Protection (VAP)
    2. 2.2 Fast Role Swap (FRS)
    3. 2.3 Processor Hot Indication
    4. 2.4 Two-Level Battery Discharge Current Limit
    5. 2.5 Pass Through Mode (PTM) Operation
    6. 2.6 Seamless Mode Transition
    7. 2.7 Current and Power Monitor
    8. 2.8 Input Source Dynamic Power Management
    9. 2.9 Power Up USB Port From Battery (USB OTG)
  4. 3Test Results
  5. 4Summary
  6. 5References

2.5 Pass Through Mode (PTM) Operation

When a USB PD3.0 PPS adapter is available, BQ25720 could operating in Pass Through Mode (PTM) to directly charging a battery to improve efficiency over the full load range. In PTM, BQ25720 keeps Q1 and Q4 always on, and Q2 and Q3 always off. The input power is passes through Q1, inductor, and Q4 to the system and through BATFET to battery.

The charger could switch operating mode from buck/buck-boost/boost to PTM and switch back from PTM to buck/buck-boost/boost by internal register setting EN_PTM. Also, the BQ25720 includes voltage protection, current protection and seamless transition for mode swapping.