Tantalum Capacitors
Capacitor Table
Designing for Load Transients
www.ti.com .......................................................................................................................................... SLTS230B – NOVEMBER 2004 – REVISED OCTOBER 2007
Tantalum type capacitors may be used at the output, and are recommended for applications where the ambient
operating temperature can be less than 0
°C. The AVX TPS, Sprague 593D/594/595, and Kemet
T495/T510/T520 capacitors series are suggested over many other tantalum types due to their rated surge, power
dissipation, and ripple current capability. As a caution, many general-purpose tantalum capacitors have
considerably higher ESR, reduced power dissipation, and lower ripple current capability. These capacitors are
also less reliable as they have lower power dissipation and surge current ratings. Tantalum capacitors that do not
have a stated ESR or surge current rating are not recommended for power applications. When specifying
Os-Con and polymer tantalum capacitors for the output, the minimum ESR limit is encountered well before the
maximum capacitance value is reached.
The capacitor table,
Table 5 and
Table 6, identifies the characteristics of capacitors from various vendors with
acceptable ESR and ripple current (rms) ratings. The recommended number of capacitors required at both the
input and output buses is identified for each capacitor type. This is not an extensive capacitor list. Capacitors
from other vendors are available with comparable specifications. Those listed are for guidance. The rms rating
and ESR (at 100 kHz) are critical parameters necessary to insure both optimum regulator performance and long
capacitor life.
The transient response of the dc/dc converter has been characterized using a load transient with a di/dt of
1 A/s. The typical voltage deviation for this load transient is given in the data sheet specification table using the
required value of output capacitance. As the di/dt of a transient is increased, the response of a converter's
regulation circuit ultimately depends on its output capacitor decoupling network. This is an inherent limitation of
any dc/dc converter once the speed of the transient exceeds its bandwidth capability. If the target application
specifies a higher di/dt or lower voltage deviation, the requirement can only be met with additional output
capacitor decoupling. In these cases, special attention must be paid to the type, value, and ESR of the
capacitors selected.
If the transient performance requirements exceed those specified in the data sheet, the selection of output
capacitors becomes more important. Review the minimum ESR in the characteristic data sheet for details on the
capacitance maximum.
Table 5. Recommended Input/Output Capacitors (PTN78000W)
CAPACITOR CHARACTERISTICS
QUANTITY
85
°C
CAPACITOR VENDOR/
EQUIVALENT
VENDOR
WORKING
MAXIMUM
PHYSICAL
COMPONENT
VALUE
SERIES
INPUT
OUTPUT
NUMBER
VOLTAGE
RIPPLE
SIZE
SERIES
(F)
RESISTANCE
BUS
(V)
CURRENT
(mm)
(ESR) (
)
(Irms) (mA)
FC( Radial)
50
180
0.119
850
10 x 16
1
EEUFC1H181
FC (SMD)
3
100
0.15
670
10 x 10,2
1 (1)
1
EEVFC1V101P
United Chemi-Con PXA
16
180
0.016
4360
8 x 12
1 (1)
≤ 1
PXA16VC180MF60
(SMD)
LXZ
50
120
0.160
620 x 2
10 x 12,5
2
1
LXZ50VB121M10X12LL
MVY50VC101M10X10TP
MVY(SMD)
50
100
0.300
500
10 x 10
1 (1)
1
(VO ≤ 5.5 V)
UWG1H101MNR1GS
Nichicon UWG (SMD)
50
100
0.300
500
10 x 10
1 (1)
1
(VO ≤ 5.5 V)
F559 (Tantalum)
10
100
0.055
2000
7.7 x 4,3
N/R (1)
≤ 3(2)
F551A107MN (VO ≤ 5 V)
HD
50
100
0.074
724
8 x 11,5
1
UHD1H101MPR
20SVP100M
Sanyo Os-Con SVP (SMD)
20
100
0.024
2500
8 x 12
1 (1)
≤ 2
(VI and VO ≤ 16 V)
16SP100M (VI and VO ≤ 14
SP
16
100
0.032
2890
10
× 5
1 (1)
≤ 2
V)
(1)
The voltage rating of the input capacitor must be selected for the desired operating input voltage range of the regulator. To operate the
regulator at a higher input voltage, select a capacitor with the next higher voltage rating.
(2)
The maximum voltage rating of the capacitor must be selected for the desired set-point voltage (VO ). To operate at a higher output
voltage, select a capacitor with a higher voltage rating.
Copyright 2004–2007, Texas Instruments Incorporated
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