AN2782 datasheet(36/39 Pages) STMICROELECTRONICS

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L6562A layout hints

AN2782

36/39

Doc ID 14763 Rev 2

L6562A layout hints

The layout of any converter is a very important phase in the design process that sometimes

does not get enough attention from the engineers. Even if it the layout phase sometimes

looks time-consuming, a good layout does indeed save time during the functional debugging

and the qualification phases. Additionally, a power supply circuit with a correct layout needs

smaller EMI filters or less filter stages which allows consistent cost savings.

The L6562A does not need any special attention to the layout, simply the general layout

rules for any power converter must be carefully applied. Basic rules are listed below which

can be used for other PFC circuits having any power level, working either in TM or with an

FOT-control mode.

Keep power and signal RTN separated. Connect the return pins of components

carrying high current such as input capacitors, sense resistors, or output capacitors as

close as possible. This point is the RTN star point. A downstream converter or ballast

must be connected to this return point.

Minimize the length of the traces relevant to the boost inductor, boost rectifier and

output capacitor.

Keep signal components as close as possible to the L6562A pins. Specifically, keep the

tracks relevant to pin #1 (INV) net as short as possible. Components and traces

relevant to the error amplifier have to be placed far from traces and connections

carrying signals with high dv/dt like the MOSFET drain.

Connect heat sinks to power GND.

Place an external copper shield around the boost inductor and connect it to power

GND.

Please connect the RTN of signal components including the feedback and MULT

dividers close to the L6562A pin #6 (GND).

Connect a ceramic capacitor (100÷470 nF) to pin #8 (Vcc) and to pin #6 (GND), close

to the L6562A. Connect this point to the RTN star point 1.

AN2782 bảng dữ liệu(PDF) 36 Page - STMicroelectronics