Datasheet

C-Capacitance- Fm
Transient-mV/A
600
700
800
900
1000 2000 3000 4000 5000
6000
7000
8000
9000
10000
3
2
1
8
5
6
7
4
WithTurboTrans
V =12V
I
WithoutTurboTrans
C-Capacitance- Fm
Transient-mV/A
600
700
800
900
1000 2000 3000 4000 5000
6000
7000
8000
9000
10000
10
5
6
7
8
9
4
3
2
1
WithTurboTrans
WithoutTurboTrans
V =8V
I
R
TT
Resistor Selection
R =40
TT
´
kW
1-(C /3300)
O
5x(C /3300)-1
O
(1)
PTV08T250W
www.ti.com .......................................................................................................................................... SLTS260E – OCTOBER 2005 – REVISED NOVEMBER 2008
Type A Capacitor Type A Capacitor
12 V Input 8 V Input
Figure 9. Cap Type A, 100 ≤ C( µ F)xESR(m Ω ) ≤ 1000, (e.g. Figure 10. Cap Type A, 100 ≤ C( µ F)ESR(m Ω ) ≤ 1000, (e.g.
Ceramic) Ceramic)
Table 2. Type A TurboTrans C
O
Values & Required R
TT
Selection Table
Transient Voltage Deviation (mV) 12 V Input 8 V Input
25% 50% 75% C
O
R
TT
C
O
R
TT
load step load step load step Minimum Required Required Minimum Required Required
(12.5 A) (25 A) (37.5 A) Output Capacitance TurboTrans Output Capacitance TurboTrans
( µ F) Resistor ( Ω ) ( µ F) Resistor ( Ω )
100 200 300 700 499 k 950 66.5 k
90 180 270 820 130 k 1100 42.2 k
80 160 240 960 63.4 k 1250 27.4 k
70 140 210 1200 34.8 k 1500 17.4 k
60 120 180 1450 19.6 k 1800 10.5 k
50 100 150 1850 9.76 k 2300 4.99 k
40 80 120 2600 3.32 k 3100 866
35 70 105 3100 845 3800 0
30 60 90 6400 0 7700 0
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming equation, see
Equation 1 :
Where C
O
is the total output capacitance in µ F. C
O
values greater than or equal to 3300 µ F require R
TT
to be a
short, 0 Ω . (R
TT
results in a negative value when C
O
> 3300 µ F.)
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