zxld1362 Zetex Semiconductors plc., zxld1362 Datasheet - Page 23

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

V
A low ESR capacitor should be used for input decoupling, as the ESR of this capacitor appears in
series with the supply source impedance and lowers overall efficiency. This capacitor has to
supply the relatively high peak current to the coil and smooth the current ripple on the input
supply.
To avoid transients into the IC, the size of the input capacitor will depend on the V
When the input voltage is close to the output voltage the input current increases which puts more
demand on the input capacitor. The minimum value of 2.2 F may need to be increased to 4.7 F;
higher values will improve performance at lower input voltages, especially when the source
impedance is high. The input capacitor should be placed as close as possible to the IC.
For maximum stability over temperature and voltage, capacitors with X7R, X5R, or better
dielectric is recommended. Capacitors with Y5V dielectric are not suitable for decoupling in this
application and should NOT be used.
If higher voltages are used and the C
suitable 1 F ceramic capacitor is also used and positioned as close the V
A suitable capacitor would be NACEW100M1006.3x8TR13F.
The following web sites are useful when finding alternatives:
Issue 1 - December 2007
© Zetex Semiconductors plc 2007
IN
capacitor selection
V
V
V
www.murata.com
www.niccomp.com
www.kemet.com
IN
IN
IN
= 6 to 40V
= 40 to 50V
= 50 to 60V
C
C
C
IN
IN
IN
= 2.2 F
= 4.7 F
= 10 F
IN
is 10 F. This can be an electrolytic capacitor provide a
23
IN
of the I
ZXLD1362
www.zetex.com
IN
C
as possible.
voltage: