ZXLD1352

ZXLD1352

Document number: DS33469 Rev. 3 - 2

17 of 21

www.diodes.com

December 2010

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Reducing Output Ripple

below:

A value of 1µF will reduce nominal ripple current by a factor three (approx.). Proportionally lower ripple can be achieved with

higher capacitor values. Note that the capacitor will not affect operating frequency or efficiency, but it will increase start-up

delay, by reducing the rate of rise of LED voltage.

Operation at low supply voltage

threshold, the device will start to operate. However, with the supply voltage below the specified minimum value, the switch duty

cycle will be high and the device power dissipation will be at a maximum. Care should be taken to avoid operating the device

under such conditions in the application, in order to minimize the risk of exceeding the maximum allowed die temperature. (See

next section on thermal considerations).

Note that when driving loads of two or more LEDs, the forward drop will normally be sufficient to prevent the device from

switching below approximately 6V. This will minimize the risk of damage to the device.

Thermal considerations

When operating the device at high ambient temperatures, or when driving maximum load current, care must be taken to avoid

exceeding the package power dissipation limits. The graph below gives details for power derating. This assumes the device to

be mounted on a 25mm

 

LX

ZXLD1352

Rs

L1

Cled

LED

D1