SLYY200A April   2021  – December 2023 LM25149 , LM25149-Q1 , LM5156-Q1 , LM5157-Q1 , LM53635-Q1 , LM60440-Q1 , LM61460-Q1 , LM61495-Q1 , LMQ62440-Q1 , LMR33630-Q1 , LMS3655-Q1 , TPS55165-Q1 , UCC12040 , UCC12050

 

  1.   1
  2.   Overview
  3.   At a glance
  4.   What is EMI?
  5.   Conventional methods to reduce EMI in the low- and high-frequency ranges
  6.   Innovations in reducing low-frequency emissions
  7.   Spread spectrum
  8.   Active EMI filtering
  9.   Cancellation windings
  10.   Innovations in reducing high-frequency emissions
  11.   HotRod™ package
  12.   Enhanced HotRod QFN
  13.   Integrated input bypass capacitor
  14.   True slew-rate control
  15.   EMI modeling capabilities
  16.   Low-frequency EMI designs using WEBENCH® design tool
  17.   Conducted and radiated EMI results published in data sheets
  18.   Conclusion
  19.   Keep product categories for low EMI

Enhanced HotRod QFN

The Enhanced HotRod quad flat no-lead (QFN) package offers all of the EMI reduction capabilities of the HotRod package and has an added advantage of even lower switch-node capacitance, resulting in much lower ringing. The resistor inductor- capacitor (RLC) parasitic on the input-voltage (VIN) and ground (GND) pins is also lower in devices with the Enhanced HotRod QFN compared to the HotRod package.

The LM60440-Q1 step-down converter comes in an Enhanced HotRod QFN, and Figure 19 shows the pinout and board layout. The Enhanced HotRod QFN not only improves efficiency but also includes a footprint that has a large die-attach pad (DAP) at the center of the package. The DAP facilitates better thermal dissipation through the PCB and reduces the rise in junction temperature by more than 15% compared to the HotRod package. In addition, lower RLC parasitics on the VIN, GND and switch-node pins also result in better efficiency and lower EMI. As expected this results in better EMI, particularly around the switch-node ringing frequency band as shown in Figure 20.