Datasheet

PTH08T240W Type B Capacitors
C − Capacitance − µF
Transient − mV/A
30
6000
5000
4000
3000
2000
1000
500
400
300
200
20
10
9
8
7
6
5
4
3
2
10000
WIth TurboTrans
Without TurboTrans
30
6000
5000
4000
3000
2000
1000
500
400
300
200
20
10
9
8
7
6
5
4
3
2
10000
WIth TurboTrans
Without TurboTrans
C − Capacitance − µF
Transient − mV/A
R
TT
+
40
ƪ
1 *
ǒ
C
O
ń1100
Ǔƫ
ƪ
ǒ
C
O
ń220
Ǔ
* 1
ƫ
(
kW
)
(3)
PTH08T240W , PTH08T241W
www.ti.com ................................................................................................................................................... SLTS264J – NOVEMBER 2005 – REVISED JUNE 2009
12-V Input 5-V Input
Figure 14. Cap Type B, 1000 < C( µ F) × ESR(m Ω ) ≤ 5000 Figure 15. Cap Type B, 1000 < C( µ F) × ESR(m Ω ) ≤ 5000
(e.g. Polymer-Tantalum) (e.g. Polymer-Tantalum)
Table 5. Type B TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 12-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 )
55 110 165 220 open 220 open
40 80 120 330 57.6 360 42.2
35 70 105 400 30.9 450 23.7
30 60 90 510 16.2 560 12.7
25 50 75 680 7.32 750 5.49
20 40 60 1000 1.58 1050 0.536
15 30 45 2100 short 2600 short
10 20 30 10500 short exceeds limit —
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming, see Equation 3 . For
V
O
> 3.45V please contact TI for C
O
and R
TT
values.
Where C
O
is the total output capacitance in µ F. C
O
values greater than or equal to 1100 µ F require R
TT
to be a
short, 0 Ω . (R
TT
results in a negative value when C
O
> 1100 µ F).
To ensure stability, a minimum amount of output capacitance is required for a given R
TT
resistor value. The value
of R
TT
must be calculated using the minimum required output capacitance determined from the capacitor
transient response charts above.
Copyright © 2005 – 2009, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Link(s): PTH08T240W PTH08T241W