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
PTH08T261 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
PTH08T261 Type A
Ceramic Capacitors
Without TurboTrans
With TurboTrans
R
TT
=40x
1-(C /1000)
O
5 x(C /1000)-1
O
(k )W
[]
PTH08T260W, PTH08T261W
www.ti.com SLTS272G –DECEMBER 2006– REVISED AUGUST 2011
PTH08T261W Type A Capacitors
12-V INPUT 5-V INPUT
Figure 10. Capacitor Type A, 100 ≤ C(μF) x Figure 11. 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
(0.75 A) (1.5 A) (2.25 A) Required Output TurboTrans Required Output TurboTrans
Capacitance (μF) Resistor (kΩ) Capacitance (μF) Resistor (kΩ)
25 50 75 200 open 200 open
20 40 60 240 150 210 634
18 35 55 300 56.2 260 97.6
15 30 45 400 23.7 340 37.4
13 25 40 560 9.76 460 16.5
10 20 30 840 2.0 660 5.9
8 15 25 5000 N/A 950 0.536
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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