Datasheet
( )
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 1.644kHz 53.6k
= = =
´ 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 100m 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
SW2
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 10mA 14 V 140mW» ´ + ´ - = ´ =
TPS54290, TPS54291, TPS54292
SLUS973 –OCTOBER 2009
www.ti.com
Compensation Gain Setting Resistor
R
COMP
programs the mid-band error amplifier gain to set the desired cross-over frequency in Equation 38.
(38)
Compensation Integrator Capacitor
An integrator capacitor provides maximum DC gain for the best possible DC regulation while programming the
compensation zero to match the natural pole of the output filter. C
COMP
is selected by Equation 40.
(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.
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Product Folder Link(s) :TPS54290 TPS54291 TPS54292