Datasheet

PTH08T240F Type B Capacitors (12-V)
6000 5000 4000 3000 2000 1000
10
7
6
5
4
3
2
1
10000
8000 9000 7000
9
8
Transient (mV/A)
C - Capacitance - mF
6000 5000 4000 3000 2000 1000
10
7
6
5
4
3
2
1
10000
8000 9000 7000
9
8
Transient (mV/A)
C - Capacitance - mF
( )
( )
( )
O
TT
O
40 1 C 5000
R k
C 1000 1
é ù
´ -
ë û
= W
é ù
-
ë û
(3)
PTH08T240F
SLTS277D – DECEMBER 2006 – REVISED MARCH 2009 ............................................................................................................................................... www.ti.com
12-V INPUT; V
O
≥ (V
I
÷ 11) 12-V INPUT; V
O
< (V
I
÷ 11)
Figure 16. (V
O
≥ V
I
÷ 11) Figure 17. V
O
< (V
I
÷ 11)
Capacitor Type B Capacitor Type B
Table 5. Type B TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) V
O
≥ V
I
/11 V
O
< V
I
/11
25% load step 50% load step 75% load step C
O
R
TT
C
O
R
TT
(2.5 A) (5 A) (7.5 A) Minimum Required Minimum Required
Required Output TurboTrans Required Output TurboTrans
Capacitance ( µ F) Resistor (k Ω ) Capacitance ( µ F) Resistor (k Ω )
25 50 75 1000 open 1000 open
20 40 60 1000 open 1600 46.4
18 36 54 1050 634 2000 23.7
15 30 45 1300 97.6 3000 8.06
12 24 36 1760 34.0 4900 0.255
10 20 30 2250 17.4 exceeds max -
8 16 24 3000 8.06 exceeds max -
5 10 15 7900 short exceeds max -
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming, see Equation 3 .
Where C
O
is the total output capacitance in µ F. C
O
values greater than or equal to 5000 µ F require R
TT
to be a
short, 0 Ω . (R
TT
results in a negative value when C
O
> 5000 µ F).
To ensure stability, the value of R
TT
must be calculated using the minimum required output capacitance
determined from the capacitor transient response charts above.
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