(

)

(

)

æ

ö

-

´

æ

ö

-

´

´

´

W

ç

÷

ç

÷

ç

÷

´ ´

è

ø

è

ø

W =

m

IN

OUT

OUT

OCP

DS(on)

SW

IN

TRIP

TRIP

V

V

V

1

I

32 R

m

2 L f

V

R

(k )

I

( A)

(

-

-

=

´

IND ripple

OUT

I

ESR

V

0.6

2

R1

R2

0.6

(

)

( )

´

´

-

´ ´

´

=

=

=

W

´

OUT

SW

SW

IND ripple

V

10mV (1 D)

10mV L f

L f

ESR

0.6 V I

0.6 V

60

TPS53353

SLUSAK2B – AUGUST 2011 – REVISED FEBRUARY 2015

www.ti.com

4. CHOOSE THE OUTPUT CAPACITORS

When organic semiconductor capacitors or specialty polymer capacitors are used, for loop stability,

capacitance and ESR should satisfy Equation 6. For jitter performance, Equation 10 is a good starting point

to determine ESR.

where

•

D is the duty factor.

•

voltage.

(10)

5. DETERMINE THE VALUE OF R1 AND R2

The output voltage is programmed by the voltage-divider resistor, R1 and R2 shown in Figure 37. R1 is

connected between VFB pin and the output, and R2 is connected between the VFB pin and GND.

Recommended R2 value is from 1 k

Ω to 20 kΩ. Determine R1 using Equation 11.

(11)

6. CHOOSE THE OVERCURRENT SETTING RESISTOR

where

•

•

(12)

1.7 m

Ω for overcurrent level of approximately 10 A.

8.2.1.3 Application Curves

Figure 39. Enable Turnon

Figure 40. Enable Turnoff

22

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