ZXLD1370

ZXLD1370

Document number: DS32165 Rev. 4 - 2

30 of 36

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March 2011

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PCB Layout considerations

PCB layout is a fundamental activity to get the most of the device in all configurations. In the following section it is possible

to find some important insight to design with the ZXLD1370 both in Buck and Buck-Boost/Boost configurations.

Figure 39: Circuit Layout

Here are some considerations useful for the PCB layout:

In order to avoid ringing due to stray inductances, the inductor L1, the anode of D1 and the drain of Q1 should be

placed as close together as possible.

The shaping capacitor C1 is fundamental for the stability of the control loop. To this end it should be placed no more

than 5mm from the SHP pin.

Input voltage pins, VIN and VAUX, need to be decoupled. It is recommended to use two ceramic capacitors of

2.2uF, X7R, 100V (C3 and C4). In addition to these capacitors, it is suggested to add two ceramic capacitors of

1uF, X7R, 100V each (C2, C8), as well as a further decoupling capacitor of 100nF close to the VIN/VAUX pins (C9).

VIN and VAUX pins can be short-circuited when the device is used in buck mode, or can be driven from a separate

supply.

APPLICATION EXAMPLES

Example 1:

2.8A Buck LED driver

In this application example, the ZXLD1370 is connected as a buck LED driver. The schematic and parts list are shown

below. The LED driver is able to deliver 2.8A of LED current with an input voltage range of 8V to 24V. In order to achieve

high efficiency at high LED current, a Super Barrier Rectifier (SBR) with a low forward voltage is used as the free wheeling

rectifier.

This LED driver is suitable for applications which require high LED current such as LED projector, automatic LED lighting

etc.

SHP pin

decoupling

Inductor, Switch

and

Freewheeling

diode