Datasheet
C − Capacitance − µF
Transient − mV/A
20
10
9
8
7
30
4000
3000
2000
1000
500
400
300
200
5000
900
600
700
800
100
40
PTH08T231 Type A
Ceramic Capacitors
Without TurboTrans
With TurboTrans
C − Capacitance − µF
Transient − mV/A
20
10
9
8
7
30
4000
3000
2000
1000
500
400
300
200
5000
900
600
700
800
100
40
PTH08T231 Type A
Ceramic Capacitors
Without TurboTrans
With TurboTrans
R
TT
=40x
1-(C /1000)
O
5 x(C /1000)-1
O
(k )W
[]
PTH08T230W, PTH08T231W
www.ti.com
SLTS265L –NOVEMBER 2005– REVISED AUGUST 2011
PTH08T231W Type A Capacitors
12-V INPUT 5-V INPUT
Figure 12. Capacitor Type A, 100 ≤ C(μF) x Figure 13. Capacitor Type A, 100 ≤ C(μF) x
ESR(mΩ) ≤ 1000 ESR(mΩ) ≤ 1000
(e.g. Ceramic) (e.g. Ceramic)
Table 4. Type A TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 12 V Input 5 V Input
C
O
R
TT
C
O
R
TT
25% load step 50% load step 75% load step Minimum Required Minimum Required
(1.5 A) (3 A) (4.5 A) Required Output TurboTrans Required Output TurboTrans
Capacitance (μF) Resistor (kΩ) Capacitance (μF) Resistor (kΩ)
45 90 135 200 open 200 open
40 80 120 240 150 210 634
35 70 105 300 56.2 260 97.6
30 60 90 400 23.7 340 37.4
25 50 75 560 9.76 460 16.5
20 40 60 840 2.0 660 5.9
15 30 45 N/A N/A 1450 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 μF. C
O
values greater than or equal to 1000 μF 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 the
capacitor transient response charts above.
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