Datasheet
PTH08T220W Type B Capacitors
Transient − mV/A
C − Capacitance − µF
2
7
3
4
5
20
9
8
6
10
Without TurboTrans
With TurboTrans
200
V
I
= 5 V
300
400
500
600
700
1000
800
900
2000
3000
4000
5000
6000
7000
10000
8000
9000
Transient − mV/A
C − Capacitance − µF
2
7
3
4
5
20
9
8
6
10
Without TurboTrans
With TurboTrans
V
I
= 12 V
200
300
400
500
600
700
1000
800
900
2000
3000
4000
5000
6000
7000
8000
9000
10000
R
TT
+ 40
ƪ
1 *
ǒ
C
O
ń1100
Ǔƫ
ƪ
ǒ
5 C
O
ń1100
Ǔ
* 1
ƫ
(
kW
)
(3)
PTH08T220W , PTH08T221W
www.ti.com
................................................................................................................................................... SLTS252K – NOVEMBER 2005 – REVISED JUNE 2009
12-V INPUT 5-V INPUT
Figure 15. Capacitor Type B, Figure 16. Capacitor Type B,
1000 < C( µ F) × ESR(m Ω ) ≤ 5000 (e.g. Polymer-Tantalum) 1000 < C( µ F) × ESR(m Ω ) ≤ 5000 (e.g. Polymer-Tantalum)
Table 5. Type B TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 12 Volt Input 5 Volt Input
25% load step 50% load step 75% load step C
O
R
TT
C
O
R
TT
(4 A) (8 A) (12 A) Minimum Required Minimum Required
Required Output TurboTrans Required Output TurboTrans
Capacitance ( µ F) Resistor (k Ω ) Capacitance ( µ F) Resistor (k Ω )
65 125 190 220 open 220 open
50 100 150 270 132 270 132
40 80 120 330 56 330 56
30 60 90 470 20.5 500 17.4
25 50 75 600 10.5 650 8.25
20 40 60 800 4.12 900 2.32
15 30 45 1500 short 1700 short
10 20 30 7000 short 10000 short
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming Equation 3 .
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 . (Equation 3 results in a negative value for R
TT
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 Figure 15 and
Figure 16 .
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