(

)

KEA

11.83dB

20

20

LOWER

UPPER

COMP

M

LOWER

10

Z

Z

10

(6.49k

20.5k )

R

50.42k

53.6k

g

Z

325 S 6.49k

´

+

´

W +

W

=

=

=

W »

W

´

m ´

W

POLE

LOAD

OUT

1

1

f

1.644 kHz

2

R

C

2

4.4

22 F

=

=

=

´ p ´

´

´ p ´

W ´

m

COMP

POLE

COMP

1

1

C

1.80 nF

2

f

R

2

1.644 kHz

53.6 k

=

=

=

´ p ´

´

´ p ´

´

W

( )

( )

(

)

(

)

(

)

(

) (

)

2

2

CON1

1

1

DS on HS

DS on LS

SW 1 RMS

P

R

D

R

1

D

I

150 m

0.413

100 m

0.587

1.51

0.275 W

æ

ö

=

´

+

´ -

´

=

W ´

+

W ´

´

=

ç

÷

è

ø

( )

( )

(

)

(

)

(

)

(

) (

)

2

2

CON2

1

1

DS on HS

DS on LS

SW 1 RMS

P

R

D

R

1

D

I

105 m

0.15

75 m

0.85

2.51

0.501W

æ

ö

=

´

+

´ -

´

=

W ´

+

W ´

´

=

ç

÷

è

ø

(

)

2

2

OSS(HS)

OSS(LS)

SW

IN max

SW1

V

(C

C

)

14

(140pF

200pF) 600kHz

P

20mW

2

2

´

+

´

´

+

´

»

=

=

f

(

)

(

)

( )

2

2

SW

IN max

OSS HS

OSS LS

SW 2

V

(C

C

)

14

(200pF

280pF) 600kHz

P

28mW

2

2

´

+

´

´

+

´

»

=

=

f

(

)

(

)

(

)

REG

DD

BP

BP

IN max

IN max

P

I

V

I

V

V

10 mA

14 V

140 mW

»

´

+

´

-

=

´

=

TPS54290, TPS54291, TPS54292

SLUS973 – OCTOBER 2009

www.ti.com

Compensation Gain Setting Resistor

(38)

Compensation Integrator Capacitor

An integrator capacitor provides maximum DC gain for the best possible DC regulation while programming the

(39)

(40)

Bootstap Capacitor

To ensure proper charging of the high-side FET gate and limit the ripple voltage on the boost capacitor, a 47-nF

boot strap capacitor is recommended.

Power Dissipation

The power dissipation in the TPS54291 is made from FET conduction losses, switching losses and regulator

losses.

Conduction losses are estimated by Equation 41 and Equation 42.

(41)

(42)

The switching losses are estimated by Equation 43 and Equation 44.

(43)

(44)

The regulator losses are estimated by Equation 45.

(45)

Total power dissipation in the device is the sum of conduction losses and switching losses for both channels plus

regulator losses, which is estimated to be 1.01 W.

24

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