SLUAAP2 March   2023 LMG2610 , UCC28782

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Design Requirement 1: Managing Thermals Induced by Power Losses
    2. 1.2 Design Requirement 2: Reducing Energy Storage Requirement by Switching at High Frequency
  4. 2A Brief Introduction to GaN's Value
  5. 3The Active Clamp Flyback
    1. 3.1 Power Loss Saving 1: Zero-Clamp Loss
    2. 3.2 Power Loss Saving 2: Zero-Voltage-Switching
  6. 4The Value of GaN in Active Clamp Flyback
  7. 5Leveraging Integrated GaN to Simplify ACF Stage
  8. 6Physical Design Implementations Using LMG2610 Integrated Half-Bridge and UCC28782 ACF Controller
    1. 6.1 UCC28782EVM-030
    2. 6.2 PMP23146
  9. 7Leverage Design Tools for ACF
  10. 8Summary
  11. 9References

6.2 PMP23146

The second design is a 45 W auxiliary power supply for server applications with the following specifications in Table 6-2.

Table 6-2 PMP23146 Specifications
Application Server Auxiliary Power Supplies
Input Voltage 250-410 Vdc
Output 12 V/3.7 A
Max. Power 45 W

The PMP23146 achieves an astounding power density of 60 W i n 3   o r   3.7 W c c . The sleek form factor is shown in Figure 6-7.

GUID-20230223-SS0I-PXBQ-WVQG-2QBPMD4JSCWC-low.jpg Figure 6-7 PMP23146 Server Auxiliary Power Supply Reference Design

This size is achieved by using a planar transformer while switching at 400 kHz. The planar transformer drastically reduces the overall height by implementing the windings in multiple layers of the PCB. The high switching frequency greatly reduces the energy storage requirement.

Additionally, the integration provided by LMG2610 reduces the total required board space as seen in Figure 6-8. The Small 7 mm × 9 mm package of LMG2610 greatly reduces the board footprint compared to a discrete design. This integration can significantly improve the power density for miniaturized designs

GUID-20230223-SS0I-GLJP-0TFG-ZQHWXHCDP06K-low.jpg Figure 6-8 PMP23146 Back-side

Figure 6-10 shows the efficiency across several input voltage levels.

GUID-20230223-SS0I-MTVR-2FCC-JLGRC44H9KZ9-low.png Figure 6-9 PMP23126 Efficiency Across Load

Additionally, the standby power consumption is kept below 100 mW.

Figure 6-10 shows the thermals captured at 390-VDC input at full load. Forced air was used with fan current limited to 200 mA.

GUID-20230221-SS0I-LQCB-0NX7-WTVGWPQ56LJS-low.png Figure 6-10 PMP23126 Thermal Images

Temperatures are managed in this design to provide a thermally reliable operation.

In all, the miniaturization of this power supply design is enabled by the combination of the ACF, LMG2610, and UCC28782.