Datasheet
PTN78020W
PTN78020H
SLTS228C – DECEMBER 2004– REVISED AUGUST 2011
www.ti.com
Tantalum Capacitors
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.
Capacitor Table
The capacitor tables, Table 5 and Table 6, identifies the characteristics of capacitors from a number of 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 ensure both optimum regulator performance and long
capacitor life.
Designing for Load Transients
The transient response of the dc/dc converter has been characterized using a load transient with a di/dt of
1 A/µs. 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.
Table 5. Recommended Input/Output Capacitors (PTN78020W)
CAPACITOR CHARACTERISTICS QUANTITY
85°C
CAPACITOR VENDOR/
EQUIVALENT
VENDOR
WORKING MAXIMUM PHYSICAL
COMPONENT
VALUE SERIES INPUT OUTPUT
NUMBER
VOLTAGE RIPPLE SIZE
SERIES
(µF) RESISTANCE BUS BUS
(V) CURRENT (mm)
(ESR) (Ω)
(mArms)
Panasonic FC( Radial) 35 330 0.068 1050 10 × 16 1 1 EEUFC1V331 (V
I
< 30 V)
FK (SMD) 50 330 0.12 900 12,5 × 13,5 1
(1)
1 EEVFK1H331Q
United Chemi-Con PXA (SMD) 16 330 0.014 4360 10 × 12,2 ≤1 PXA16VC331MJ12TP
1
(1)
(V
I
< 14 V)
PS 16 330 0.014 5500 10 × 12,5 1
(1)
≤ 1 16PS330M J12 (V
I
< 14 V)
LXZ 35 220 0.090 760 10 × 12,5 2 LXZ35VB221M10X12LL
1
(1)
(V
I
< 30 V)
MVZ(SMD) 25 470 0.09 670 10 × 10 1 1 MVZ25VC471MJ10TP
(V
I
< 24 V) (V
O
≤ 5.5 V)
Nichicon UWG (SMD) 35 330 0.15 670 10 × 10 1 1 UWG1V331MNR1GS
SP 20 180 0.032 4280 10 ×10.5 2
(1)
≤ 2 20SP180M (V
I
~V
O
≤ 16 V)
Sanyo Os-Con SVP (SMD) 16 330 0.020 4700 10 × 12,7 1
(1)
≤ 1 16SVP330M (V
I
≤ 14 V)
SP 20 180 0.032 4280 10 ×10.5 2
(1)
≤ 2 20SP180M (V
I
≤ 16 V)
20 100 0.085 1543 7,3 L × 4,3 N/R
(2)
≤ 3 TPSV107M020R0085
W × 4,1 H (V
O
≤ 10 V)
AVX Tantalum TPS (SMD)
20 100 0.200 > 817 3225 N/R
(2)
≤ 3 TPSE107M020R0200
(V
O
≤ 10 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) Not recommended (N/R). The voltage rating does not meet the minimum operating limits in most applications.
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