Datasheet

40
30
20
4
5000
4000
3000
1000
900
300
200
500
400
700
600
800
2000
10
With TurboTrans
Without TurboTrans
6
5
8
7
9
C − Capacitance − µF
Transient − mV/A
C − Capacitance − µF
Transient − mV/A
Without TurboTrans
With TurboTrans
40
30
20
4
5000
4000
3000
1000
900
300
200
500
400
700
600
800
2000
10
6
5
8
7
9
R
TT
+ 40
1 *
ǒ
C
O
ń1250
Ǔ
ǒ
C
O
ń250
Ǔ
* 1
kW
(3)
PTH04T260W , PTH04T261W
www.ti.com .................................................................................................................................................. SLTS273E – SEPTEMBER 2006 – REVISED JULY 2009
PTH04T260W Type B Capacitors
5-V Input 3.3-V Input
Figure 12. Capacitor Type B, 1000 < C( µ F) x ESR(m Ω ) ≤ Figure 13. Capacitor Type B, 1000 < C( µ F) x ESR(m Ω ) ≤
5000 5000
(e.g. Polymer-Tantalum) (e.g. Polymer-Tantalum)
Table 5. Type B TurboTrans C
O
Values and Required R
TT
Selection Table
Transient Voltage Deviation (mV) 5-V Input 3.3-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 ( µ F) Resistor (k Ω ) Capacitance ( µ F) Resistor (k Ω )
30 60 90 250 open 250 open
25 50 75 300 165 300 165
20 40 60 400 47.5 400 47.5
15 30 45 570 16.9 570 16.9
10 20 30 940 3.57 960 3.32
8 16 24 1250 short 1280 short
6 12 18 3200 short 3200 short
R
TT
Resistor Selection
The TurboTrans resistor value, R
TT
can be determined from the TurboTrans programming equation:
Where C
O
is the total output capacitance in µ F. C
O
values greater than or equal to 1250 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 the
capacitor transient response charts above.
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