LTC3203 datasheet(13/16 Pages) LINER

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LTC3203/LTC3203-1

LTC3203B/LTC3203B-1

32031fa

APPLICATIO S I FOR ATIO

Figure 5. 10nH Inductor Used for Input Noise Reduction

AVX

www.avxcorp.com

Kemet

www.kemet.com

Murata

www.murata.com

Taiyo Yuden

www.t-yuden.com

Vishay

www.vishay.com

TDK

www.component.tdk.com

A 10nH inductor will reject the fast current notches,

thereby presenting a nearly constant current load to the

input power supply. For economy the 10nH inductor can

be fabricated on the PC board with about 1cm (0.4") of PC

board trace.

Flying Capacitor Selection

Warning: Polarized capacitors such as tantalum or

aluminum should never be used for the flying capacitors

since their voltage can reverse upon start-up of the

LTC3203/LTC3203-1/LTC3203B/LTC3203B-1. Low ESR

ceramic capacitors should always be used for the flying

capacitors.

The flying capacitors control the strength of the charge

pump. In order to achieve the rated output current, it is

necessary to have at least 2.2

µF of capacitance for each of

the flying capacitors.

Ceramic capacitors of different materials lose their ca-

pacitance with higher temperature and voltage at different

rates. For example, a capacitor made of X7R material will

retain most of its capacitance from –40

°Cto85°Cwhereas

Z5U or Y5V style capacitors will lose considerable capaci-

tance over that range. Z5U and Y5V capacitors may also

have a poor voltage coefficient causing them to lose 60%

or more of their capacitance when the rated voltage is

applied. Therefore, when comparing different capacitors,

it is often more appropriate to compare the amount of

achievable capacitance for a given case size rather than

comparing the specified capacitance value. For example,

over rated voltage and temperature conditions, a 4.7

µF,

10V, Y5V ceramic capacitor in a 0805 case may not

provide any more capacitance than a 1

µF, 10V, X5R or

X7R capacitor available in the same 0805 case. In fact,

over bias and temperature range the 1

µF, 10V, X5R or X7R

will provide more capacitance than the 4.7

µF, 10V, Y5V

capacitor. The capacitor manufacturer’s data sheet should

be consulted to determine what value of capacitor is

needed to ensure minimum capacitance values are met

over operating temperature and bias voltage.

Below is a list of ceramic capacitor manufacturers and

how to contact them:

3203 F05

LTC3203*

VIN

GND

9, 11

0.1

µF2.2µF

10nH

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