Datasheet
C − Capacitance − µF
Transient − mV/A
40
30
20
4
5000
4000
3000
1000
900
300
200
500
400
700
600
800
2000
10
6
5
8
7
9
PTH04T231 Type A
Ceramic Capacitors
Without TurboTrans
With TurboTrans
C − Capacitance − µF
Transient − mV/A
40
30
20
4
5000
4000
3000
1000
900
300
200
500
400
700
600
800
2000
10
6
5
8
7
9
PTH04T231 Type A
Ceramic Capacitors
Without TurboTrans
With TurboTrans
R
TT
+ 40
1 *
ǒ
C
O
ń1500
Ǔ
ǒ
C
O
ń300
Ǔ
* 1
kW
(2)
PTH04T230W , PTH04T231W
SLTS271C – SEPTEMBER 2006 – REVISED MARCH 2009 .............................................................................................................................................
www.ti.com
PTH04T231W - Type A Ceramic Capacitors
5-V Input 3.3-V Input
Figure 10. Capacitor Type A, 100 < C( µ F) x ESR(m Ω ) ≤ Figure 11. Capacitor Type A, 100 < C( µ F) x ESR(m Ω ) ≤
1000 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) 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
(1.5 A) (3 A) (4.5 A) Required Output TurboTrans Required Output TurboTrans
Capacitance ( µ F) Resistor (k Ω ) Capacitance ( µ F) Resistor (k Ω )
40 80 120 300 open 300 open
35 70 105 320 549 300 open
30 60 90 400 93.1 350 226
25 50 75 510 37.4 450 59.0
20 40 60 700 15.8 610 22.6
15 30 45 1050 4.75 920 7.50
10 20 30 3300 short 2250 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 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 the
capacitor transient response charts above.
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