Datasheet
1000
600
700
5000
4000
3000
2000
10000
6000
8
5
6
Without TurboTrans
With TurboTrans
800
900
7000
8000
9000
4
2
3
1
7
C - Capacitance - mF
Transient - mV/A
1000
600
700
5000
4000
3000
2000
10000
6000
8
5
6
Without TurboTrans
With TurboTrans
800
900
7000
8000
9000
4
2
3
1
7
C - Capacitance - mF
Transient - mV/A
( )
( )
O
TT
O
1 C 3300
R 40 (k )
5 C 3300 1
-
= ´ W
´ -
PTH08T250W
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SLTS278G –NOVEMBER 2010–REVISED MARCH 2009
PTH08T250W Type C Capacitors
12-V INPUT 5-V INPUT
Figure 14. Capacitor Type C, Figure 15. Capacitor Type C,
5000 < C(mF)×ESR(mΩ) ≤ 10,000(e.g. OS-CON) 5000 < C(mF)×ESR(mΩ) ≤ 10,000(e.g. OS-CON)
Table 5. Type C TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 12 Volt Input 5 Volt Input
25% load 50% load 75% load C
O
R
TT
C
O
R
TT
step step step Minimum Required Required Minimum Required Required
(12.5 A) (25 A) (37.5 A) Output TurboTrans Output TurboTrans
Capacitance (mF) Resistor (kΩ) Capacitance (mF) Resistor (kΩ)
85 170 255 660 open 660 open
75 150 225 720 340 800 143
60 120 180 950 64.9 1050 46.4
50 100 150 1200 30.9 1350 22.6
40 80 120 1600 14.3 1800 10.5
30 60 90 2250 5.23 2650 2.61
25 50 75 2800 1.87 3850 short
20 40 60 6000 short - -
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming Equation 3.
(3)
Where C
O
is the total output capacitance in mF. C
O
values greater than or equal to 3300 mF require R
TT
to be a
short, 0Ω. (Equation 3 results in a negative value for R
TT
when C
O
> 3300 mF).
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 14 and
Figure 15.
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