Application Notes continued
PT6920/PT6930Series
Capacitor Recommendations for the Dual-Output
PT6920/30 Regulator Series
Tantalum Capacitors
Input Capacitors:
Tantalum type capacitors can be used for the output but only
the AVX TPS series, Sprague 593D/594/595 series or Kemet
T495/T510 series. The AVX TPS series, Kemet or Sprague
series tantalums are recommended over many other types
due to their higher rated surge, power dissipation, and ripple
current capability. As a caution the TAJ series by AVX is not
recommended. This series has considerably higher ESR,
reduced power dissipation and lower ripple current capability.
The TAJ Series is a less reliable when compared to the AVX
TPS series when determining power dissipation capability.
Tantalum types are recommended for applications where
ambient temperatures fall below 0°C.
The recommended input capacitance is determined by 1.0
ampere minimum ripple current rating and 330µF minimum
capacitance (300µF for Oscon® or low ESR tantalum).
Ripple current and <100mΩ equivalent series resistance
(ESR) values are the major considerations, along with tem-
perature, when designing with different types of capacitors.
Tantalum capacitors have a recommended minimum voltage
rating of 2 × the maximum DC voltage + AC ripple. This is
necessary to insure reliability for input voltage bus applica-
tions.
Output Capacitors: C2(Required), C3(Optional)
The ESR of the required capacitor (C2) must not be greater
than 150mΩ. Electrolytic capacitors have poor ripple per-
formance at frequencies greater than 400kHz but excellent
low frequency transient response. Above the ripple fre-
quency, ceramic capacitors are necessary to improve the
transient response and reduce any high frequency noise
components apparent during higher current excursions.
Preferred low ESR type capacitor part numbers are identified
in Table 1. The optional 100µF capacitor (C3) for Vo2 can
have an ESR of up to 200mΩ for optimum performance
and ripple reduction. (Note: Vendor part numbers for the
optional capacitor, C3, are not identified in the table. Use the
same series selected for C2)
Capacitor Table
Table 1 identifies the characteristics of capacitors from a
number of vendors with acceptable ESR and ripple current
(rms) ratings. The 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 ripple current rating and ESR
(Equivalent Series Resistance at 100kHz) are critical parameters
necessary to insure both optimum regulator performance and
long capacitor life.
Table 1: Input/Output Capacitors
Capacitor
Vendor/
Capacitor Characteristics
Quantity
Component
Series
Working
Voltage
85°C Maximum
Ripple
Current(Irms)
(ESR) Equivalent
Series Resistance
Physical
Size(mm)
Input
Bus
Output
Bus
Value(µF)
Vendor Number
Panasonic
FC
25V
35V
35V
560µF
390µF
330µF
0.0065W
0.065W
0.117W
1205mA
1205mA
555mA
12.5x15
12.5x15
8x11.5
1
2
(a)
1
1
1
EEUFC1E561S
EEUFC1V391S
EEUFC1C331
United
Chemi -con
LXV/FS/
LXZ
16V
35V
10V
20V
330µF
470µF
330µF
150µF
0.120W
0.052W
0.025W
0.030/2W
555mA
1220mA
3500mA
3200mA
8x12
(a)
1
1
LXZ16VB331M8X12LL
LXZ35VB471M10X20LL
10FS330M
10x20
1
10x10.5
10x10.5
1
(N/R)
(N/R)
2
20FS150M
Nichicon
PL
PM
35V
35V
50V
560µF
330µF
470µF
0.048W
0.065/2W
0.046W
1360mA
1020mA
1470mA
16x15
12.5x15
18x15
1
1
1
1
1
1
UPL1V561MHH6
UPL1V331MHH6
UPM1H4711MHH6
Panasonic
FC
Surface Mtg
10V
35V
16V
1000µF
330µF
330µF
0.043W
0.065W
0.150W
1205mA
1205mA
670mA
12x16.5
12.5x16
10x10.2
1
1
(a)
1
1
1
EEVFC1A102LQ
EEVFC1V331LQ
EEVFC1C331P
10V
10V
20V
330µF
330µF
150µF
0.025W
0.025W
0.024/2W
>3500mA
>3800mA
3600mA
10.0x10.5
10.3x10.3
10.3x10.3
1
1
2
(N/R)
(N/R)
(N/R)
10SS330M
10SV300M
Oscon- SS
SV
20SV150M
SV= Surface Mount
AVX
Tantalum
TPS
10V
10V
10V
330µF
330µF
220µF
0.100/2W
0.100/2W
0.095W
>2500mA
>3000mA
>2000mA
7.3Lx
4.3Wx
4.1H
2
2
2
1
1
2
TPSV337M010R0100
TPSV337M010R0060
TPSV227M0105R0100
Kemet
T510
T495
10V
10V
330µF
220µF
0.033W
0.070W/2=0.035W
1400mA
>2000mA
7.3Lx5.7W
x 4.0H
2
2
1
2
T510X337M010AS
T495X227M010AS
7.3Lx
6.0Wx
4.1H
Sprague
594D
10V
10V
330µF
220µF
0.0450W
0.065W
2350mA
>2000mA
2
2
1
2
4D337X0010R2T
594D227X0010D2T
(a) -Not recommended. The maximum ripple current rating of these capacitors does not meet the operating limits.
(N/R) -Oscon Type Capcitors are not recommended for this application due to extremely low equivatlent series resistance (ESR)
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