Datasheet

PTH08T240F Type B Capacitors
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
(2)
PTH08T240F
www.ti.com ............................................................................................................................................... SLTS277D – DECEMBER 2006 – REVISED MARCH 2009
8-V Input 5-V Input
Figure 14. Capacitor Type B, Figure 15. Capacitor Type B,
1000 < C( µ F) × ESR(m Ω ) ≤ 5000 1000 < C( µ F) × ESR(m Ω ) ≤ 5000
(e.g. Polymer-Tantalum) (e.g. Polymer-Tantalum)
Table 4. Type B TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 8-V Input 5-V Input
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 )
20 40 60 1000 open 1060 576
18 36 54 1040 866 1200 147
16 32 48 1200 147 1400 71.5
14 28 42 1440 64.9 1660 40.2
12 24 36 1760 34.0 2020 23.2
10 20 30 2230 18.2 2550 12.7
8 16 24 3000 8.06 3400 5.36
6 12 18 4350 1.54 4900 0.205
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming, see Equation 2 .
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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