LTC3535

13

3535fa

APPLICATIONS INFORMATION

4.7µF to 10µF output capacitor is sufficient for most ap-

plications. Larger values may be used to obtain extremely

low output voltage ripple and improve transient response.

X5R and X7R dielectric materials are preferred for their

ability to maintain capacitance over wide voltage and

temperature ranges. Y5V types should not be used.

TheinternalloopcompensationoftheLTC3535isdesigned

tobestablewithoutputcapacitorvaluesof4.7µForgreater

(withouttheneedforanyexternalseriesresistor).Although

ceramic capacitors are recommended, low ESR tantalum

capacitors may be used as well.

A small ceramic capacitor in parallel with a larger tantalum

capacitormaybeusedindemandingapplicationsthathave

large load transients. Another method of improving the

transientresponseistoaddasmallfeed-forwardcapacitor

to FB). A typical value of 22pF will generally suffice.

Low ESR input capacitors reduce input switching noise

and reduce the peak current drawn from the battery. It

follows that ceramic capacitors are also a good choice

for input decoupling and should be located as close as

possible to the device. A 2.2µF input capacitor is sufficient

for most applications, although larger values may be

used without limitations. Table 2 shows a list of several

ceramiccapacitormanufacturers.Consultthemanufactur-

ers directly for detailed information on their selection of

ceramic capacitors.

Table 2. Capacitor Vendor Information

SUPPLIER

PHONE

WEBSITE

AVX

(803) 448-9411

www.avxcorp.com

Murata

(714) 852-2001

www.murata.com

Taiyo-Yuden

(408) 573-4150

www.t-yuden.com

TDK

(847) 803-6100

www.component.tdk.com

Samsung

(408) 544-5200

www.sem.samsung.com

TYPICAL APPLICATION

3535 TA02

4.7µH

0.8V

TO 1.5V

3.3V

30mA

10µF

0.47F

1M

4.25V

2.2µF

2.2µF

4.7µH

1.78M

392k

1M

1.5M

499k

SW

LTC3535

FB1

FB2

SW2

GND

GND

SHDN1

SHDN2

*POWERSTOR PA-5R0H474-R

+

Single Cell to 3.3V Converter with 20 Seconds of Holdup with 30mA Load

1V/DIV

2V/DIV

5s/DIV

3535 TA02b

2V/DIV