LTM4664 datasheet(34/138 Pages) AD

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power density. The CFLY2 can be calculated based on the

equation below:

IOUT2(MAX) =6A

CFLY =

IOUT2(MAX)

2• fSW • VCFLY2(RIPPLE)

∼ 62µF =

2•200kHz •0.24V

Consider the ceramic capacitance derating at 12VDC bias

voltage, 8 of 10μF/X7R/50V ceramic capacitors are paral-

leled as flying capacitors.

Consider the ceramic capacitance derating at 24V and

12V DC bias voltage.

The worst case RMS current may be 40% higher than the

maximum output current. So the worst case RMS on each

capacitor can be estimated by this equation:

IRMS1(MAX) =

IOUT1(MAX) • 140%

N= #of CFLY1capacitors inparallelin stage1

0.525A =

3A •1.4

Each capacitor is rated for 2A IRMS,no issue

IRMS2(MAX) =

IOUT2(MAX) • 140%

N= #of CFLY1capacitors inparallelin stage1

1.05A =

6A •1.4

Each capacitor is rated for 2A IRMS,no issue

The output capacitor selection is similar to the flying

capacitor selection. More output capacitors result smaller

output voltage ripple. The output capacitor has less than

1/3 the CFLY RMS current, and the output capacitor can

be much less than the flying capacitor. Some of output

capacitors may be connected between input and output

to serve as input capacitors at the same time. However

the voltage rating of those capacitors has to be selected

based on the input voltage instead of the output voltage.

Capacitors to use for 4:1 Divider

CAPACITOR

VENDOR

VALUE

(μF)

VOLTAGE

(V)

PART NUMBER

Murata

GRM32ER71H106KA12

TDK

C3225X7R1H106M250AC

Murata

GRM32ER71G226KE15L

Taiyo Yuden

TMK325BJ226MMHT

LTM4664A

Rev. 0

For more information www.analog.com

4:1 DIVIDER APPLICATION INFORMATION

LTM4664 Datasheet(PDF) 34 Page - Analog Devices

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