Datasheet
PTH08T221W Type A / Ceramic Capacitors
20
10
9
8
7
6
5
4
3
4000
3000
2000
1000
500
400
300
200
5000
900
600
700
800
Transient − mV/A
C − Capacitance − µF
Without TurboTrans
With TurboTrans
PTH08T221W
Type A Ceramic Capacitors
20
10
9
8
7
6
5
4
3
4000
3000
2000
1000
500
400
300
200
5000
900
600
700
800
Transient − mV/A
C − Capacitance − µF
Without TurboTrans
With TurboTrans
PTH08T221W
Type A Ceramic Capacitors
R
TT
+ 40
ƪ
1 *
ǒ
C
O
ń1500
Ǔƫ
ƪ
ǒ
5 C
O
ń1500
Ǔ
* 1
ƫ
(
kW
)
(2)
PTH08T220W , PTH08T221W
SLTS252K – NOVEMBER 2005 – REVISED JUNE 2009 ...................................................................................................................................................
www.ti.com
12-V INPUT 5-V INPUT
Figure 13. Capacitor Type A, Figure 14. Capacitor Type A,
100 ≤ C( µ F) × ESR(m Ω ) ≤ 1000 (e.g. Ceramic) 100 ≤ C( µ F) × ESR(m Ω ) ≤ 1000 (e.g. Ceramic)
Table 4. Type A 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 )
75 150 225 300 open 300 open
65 130 195 420 78.7 430 68.1
55 110 165 530 33.2 550 30.9
50 100 150 700 15.4 730 13.7
45 90 135 835 10.0 870 8.87
40 80 120 1000 5.76 1050 4.87
35 70 105 1250 2.10 1300 1.62
30 60 90 1730 short 4200 short
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming Equation 2 .
Where C
O
is the total output capacitance in µ F. C
O
values greater than or equal to 1500 µ F require R
TT
to be a
short, 0 Ω .
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 13 and
Figure 14 .
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