zxld1601 Zetex Semiconductors plc., zxld1601 Datasheet - Page 9

• Manufacturer Part Number: zxld1601
• Description: Zxld1601 - Adjustable Dc-dc Boost Converter With Internal Switch In Sc70
• Manufacturer: Zetex Semiconductors plc.

Capacitor selection
A ceramic capacitor grounded close to the GND pin of
the package is recommended at the output of the
d e v i c e . S u r f a c e m o u n t t y p e s o f f e r t h e b e s t
performance due to their lower inductance. A
minimum value of 0.22µF is advised, although higher
values will lower switching frequency and improve
efficiency especially at lower load currents. A higher
value will also minimize ripple when using the device
to provide an adjustable dc output current.
A good quality, low ESR capacitor should also be used
for input decoupling, as the ESR of this capacitor is
effectively in series with the 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. A minimum
value of 4.7µF is acceptable if the input source is close
to the device, but higher values will improve
performance at lower input voltages, when the source
impedance is high. The input capacitor should be
mounted as close as possible to the IC
Inductor selection
The choice of inductor will depend on available board
space as well as required performance. Small value
inductors have the advantage of smaller physical size
and may offer lower series resistance and higher
saturation current compared to larger values. A
disadvantage of lower inductor values is that they
result in higher frequency switching, which in turn
causes reduced efficiency due to switch losses. Higher
inductor values can provide better performance at
lower supply voltages. However, if the inductance is
too high, the output power will be limited by the
internal oscillator, which will prevent the coil current
from reaching its peak value. This condition will arise
whenever the ramp time (I
nominal 5µs maximum ‘on’ time limit for the LX output.
ISSUE 3 - AUGUST 2004
Part No.
CMD4D11-100MC
DO1608-103
LQH31CN100
LB2012Y100MR
( H)
10
10
10
10
L
LX(peak)
0.457
DCR
0.16
( )
1.3
0.5
x L/V
IN
I
0.23
(A)
0.5
1.1
0.1
SAT
) exceeds the
Manufacturer
Sumida
www.sumida.com
Coilcraft
www.coilcraft.com
Murata
www.murata.com
Taiyo Yuden
www.t-yuden.com
9
For maximum stability over temperature, capacitors
with X7R dielectric are recommended, as these have a
much smaller temperature coefficient than other types.
A table of recommended manufacturers is provided
below:
Recommended inductor values for the ZXLD1601 are
in the range 6.8µH to 22µH. The inductor should be
mounted as close to the device as possible with low
resistance connections to the LX and VIN pins.
Suitable coils for use with the ZXLD1601 are shown in
the table below:
Manufacturer
Murata
Taiyo Yuden
Kemet
AVX
www.avxcorp.com
www.t-yuden.com
www.kement.com
www.murata.com
ZXLD1601
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