ZXLD1350

30V 350mA LED DRIVER with AEC-Q100

ZXLD1350

Document number: DS33468 Rev. 8 - 2

20 of 22

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March 2011

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Application Information (Continued)

Layout considerations

LX pin

The LX pin of the device is a fast switching node, so PCB tracks should be kept as short as possible. To minimize ground

'bounce', the ground pin of the device should be soldered directly to the ground plane.

Coil and decoupling capacitors

It is particularly important to mount the coil and the input decoupling capacitor close to the device to minimize parasitic

resistance and inductance, which will degrade efficiency. It is also important to take account of any track resistance in series

with current sense resistor RS.

ADJ pin

The ADJ pin is a high impedance input, so when left floating, PCB tracks to this pin should be as short as possible to reduce

noise pickup. A 100nF capacitor from the ADJ pin to ground will reduce frequency modulation of the output under these

conditions. An additional series 10k

Ω resistor can also be used when driving the ADJ pin from an external circuit (see below).

This resistor will provide filtering for low frequency noise and provide protection against high voltage transients.

ZXLD1350

GND

ADJ

100nF

GND

10k

High voltage tracks

Avoid running any high voltage tracks close to the ADJ pin, to reduce the risk of leakage due to board contamination. Any

such leakage may raise the ADJ pin voltage and cause excessive output current. A ground ring placed around the ADJ pin

will minimize changes in output current under these conditions.