Notes
PT6940 Series
Tantalum Capacitors
Capacitor Recommendations for the
Dual-Output PT6940 Regulator Series
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. These capacitors are recommended
over many other tantalum 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 dissipa-
tion, and lower ripple current capability. The TAJ series is
less reliable than the AVX TPS series when determining
power dissipation capability. Tantalum or Oscon® types
are recommended for applications where ambient tem-
peratures fall below 0°C.
Input Capacitor:
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 twice the maximum DC voltage + AC ripple. This
is necessary to insure reliability for input voltage bus appli-
cations
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.
Output Capacitors: Co1/Co2
The ESR of the required capacitors, Co1 & Co2 must not be
greater than 150mΩ. Electrolytic capacitors have poor
ripple performance at frequencies greater than 400kHz
but excellent low frequency transient response. Above the
ripple frequency, 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.
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
(ESR) Equivalent
Series Resistance
85°C Maximum Ripple
Current(Irms)
Physical
Size(mm)
Input
Bus
Output
Bus
Value(µF)
Vendor Number
Panasonic
FC
25V
35V
35V
560µF
390µF
330µF
0.0065Ω
0.065Ω
0.117Ω
1205mA
1205mA
555mA
12.5x15
12.5x15
8x11.5
1
2
N/R
1
1
1
EEUFC1E561S
EEUFC1V391S
EEUFC1C331
United
16V
35V
10V
20V
330µF
470µF
330µF
150µF
0.120Ω
0.052Ω
0.025Ω
555mA
1220mA
3500mA
3200mA
8x12
10x20
10x10.5
10x10.5
N/R
1
1
1
2
LXZ16VB331M8X12LL
LXZ35VB471M10X20LL
10FS330M
Chemi-Con
LXV/FS/
LXZ
1
1
2
0.030÷2 Ω
20FS150M
35V
35V
50V
560µF
330µF
470µF
0.048Ω
0.065÷2 Ω
0.046Ω
1360mA
1020mA
1470mA
16x15
12.5x15
18x15
1
1
1
1
1
1
UPL1V561MHH6
UPL1V331MHH6
UPM1H4711MHH6
Nichicon
PL/ PM
Panasonic
FC
(Surface Mtg)
10V
35V
16V
1000µF
330µF
330µF
0.043Ω
0.065Ω
0.150Ω
1205mA
1205mA
670mA
12x16.5
12.5x16
10x10.2
1
1
N/R
1
1
1
EEVFC1A102LQ
EEVFC1V331LQ
EEVFC1C331P
Oscon- SS
SV
10V
10V
20V
330µF
330µF
150µF
0.025Ω
0.025Ω
0.024÷2 Ω
>3500mA
>3800mA
3600mA
10.0x10.5
10.3x10.3
10.3x10.3
1
1
2
1
1
2
10SS330M
10SV300M
20SV150M
SV= Surface Mount
AVX
Tantalum
TPS
10V
10V
10V
330µF
330µF
220µF
0.100÷2 Ω
0.100÷2 Ω
0.095Ω
>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
0.033Ω
0.07Ω÷2 =0.035Ω
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
0.045Ω
0.065Ω
2350mA
>2000mA
2
2
1
2
4D337X0010R2T
594D227X0010D2T
N/R –Not recommended. The voltage ratingdoes not meet the minimum operating limits.
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