zxld1362 Zetex Semiconductors plc., zxld1362 Datasheet - Page 25

• Manufacturer Part Number: zxld1362
• Description: 1a Led Driver With Internal Switch
• Manufacturer: Zetex Semiconductors plc.

ZXLD1362
Diode selection
For maximum efficiency and performance, the rectifier (D1) should be a fast low capacitance
Schottky diode* with low reverse leakage at the maximum operating voltage and temperature.
They also provide better efficiency than silicon diodes, due to a combination of lower forward
voltage and reduced recovery time.
It is important to select parts with a peak current rating above the peak coil current and a
continuous current rating higher than the maximum output load current. It is very important to
consider the reverse leakage of the diode when operating above 85°C. Excess leakage will
increase the power dissipation in the device and if close to the load may create a thermal runaway
condition.
The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will
increase the peak voltage on the LX output. If a silicon diode is used, care should be taken to
ensure that the total voltage appearing on the LX pin including supply ripple, does not exceed the
specified maximum value.
*A suitable Schottky diode would be 30BQ100PBF (IR).
Issue 1 - December 2007
25
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