Zxsc300, Top copper drill holes bottom copper silk screen – Diodes ZXSC300 User Manual
Page 9
ZXSC300
ISSUE 4 - SEPTEMBER 2007
9
Output Power Calculation
By making the above assumptions for inductance and
peak current the output power can be determined by:
P
(V
V
x I
I
OUT
OUT
IN
PK
MIN
=
+
)
(
)
2
x
T
T
T
OFF
ON
OFF
(
)
+
Note: V
OUT
= output voltage + Schottky rectifier voltage
drop
where
T
OFF
≅ 1.7µs (internally set by ZXSC300)
and
T
T
V
V
V
ON
OFF
OUT
IN
IN
=
−
(
)
and
I
I
( V
- V
x T
L
MIN
PK
OUT
IN
OFF
=
−
)
O p e r a t i n g f r e q u e n c y c a n b e d e r i v e d b y :
F
T
T
ON
OFF
=
+
1
(
)
Capacitor selection
For pulsed operation, as in the maximum battery life
solution, no capacitors are required at the output to
the LED. For rectified operation, as in the maximum
brightness solution, a small value ceramic capacitor
is required, typically 2.2uF.
Generally an input capacitor is not required, but a
small ceramic capacitor may be added to aid EMC,
typically 470nF to 1uF.
Demonstration board
A demonstration board for the Maximum battery life
solution, is available upon request. These can be
obtained through your local Zetex office or through
Zetex web pages. For all reference designs Gerber
files and bill of materials can be supplied.
Layout of Maximum battery life solution
Top Copper
Drill Holes
Bottom Copper
Silk Screen