SLVT229 December   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 High Side Gate Drive Circuit
      2. 2.2.2 PWM Generation Circuit
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC21330-Q1 Overview
      2. 2.3.2 UCC27211A-Q1 Overview
      3. 2.3.3 TPS1212-Q1 Overview
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Efficiency Data
      2. 3.3.2 Efficiency Graphs
      3. 3.3.3 Output Voltage Ripple
      4. 3.3.4 Thermal Images
      5. 3.3.5 Switch Voltage Stress of High Side Switches
      6. 3.3.6 Load Transients
      7. 3.3.7 Reverse Step-up Operation of SCC
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 PCB Layout Recommendations
    2. 4.2 Documentation Support
    3.     Trademarks

1 System Description

With the emergence of the 48V low voltage power net in battery electric vehicles (48V white paper: 48V Automotive Systems: Why Now?), a closer examination of the overall low-voltage system is underway. The shift from 12V to 48V does transition most of the high power (≥60W) low voltage loads to the 48V rail; however, 12V legacy loads still remain. When implementing a 48V low voltage rail in a zone architecture, each zone control module needs 500W to 1000W for the 12V loads for power switches and motor drives, as shown in Figure 1-1. And this power requirement still demands high-performance converters that address efficiency and power density challenges, as the efficiency and power density have a major impact in the total footprint and heat loss of the zonal control modules. Smaller footprints and less thermal dissipation help save cost in the board manufacturing as well as the mechanical and cooling design of the module. In addition to the cost aspect, higher efficiency and lighter total weight can also help extend the range of a battery electric vehicle, which is yet another critical parameter from user perspective.

PMP41150 Typical Power Tree for 48V Zonal Architecture Figure 1-1 Typical Power Tree for 48V Zonal Architecture

The reference design describes a Switched Capacitor Converter (SCC) that can be used in 48V zonal control modules (TIDA-020094 reference design). The converter operates over a wide range of 36V to 52V (absolute max at 70V) to deliver either 4:1 or 3:1 conversion ratio for different choices of output rails. The converter can achieve as high as 96.7% and 97.6% full-load (960W) efficiency under 4:1 and 3:1 conversion ratio, respectively. The switched capacitor converter power stage size is only 70mm × 55mm × 2.85mm providing a smaller design size compared to other high power DC-DC topologies that require an inductor. In addition, 48V zonal control module often requires bidirectional power flow to encounter system challenges in jump-start by external 12V battery and collecting back EMF from high-power inductive loads. The SCC topology is bi-directional by design and supports these system challenges.

The reference design uses TLC555-Q1 to generate a PWM control signal, where the switching frequency is able to adjust based on the output load. At lighter load, the switching frequency is decreased to about 140kHz to reduce gate drive loss and switching loss. The flying capacitors (C1, C2 and C3 in Figure 2-1) can utilize the parasitic inductance and produce resonance current waveform, enabling soft switching for higher efficiency. Therefore, at higher load the switching frequency is increased to resonance (about 300kHz) where switching loss can be even lower.