PT6980 Datasheet, PDF (8/12 Pages) Texas Instruments – 10-A 12V-Input Dual Output Integrated Switching Regulator

Application Notes
PT6980 Series
Capacitor Recommendations for the
Dual-Output PT6980 Regulator Series
Input Capacitors:
The recommended input capacitance is determined by 1.0
ampere minimum ripple current rating and 330µF minimum
capacitance . Ripple current and <100mΩ equivalent se-
ries resistance (ESR) values are the major considerations,
along with temperature, 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 applications
Output Capacitors: C₂(Required), C₃(Optional)
The ESR of the required capacitor (C₂) must not be greater
than 50mΩ. 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 V₂out 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)
Tantalum Capacitors
Tantalum type capacitors may be used at 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 also less reliable than
the AVX TPS series when determining power dissipation
capability. Tantalum or Oscon® types are recommended
for applications where ambient temperatures fall below 0°C.
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/
Component
Series
Working
Voltage
Value(µF)
Capacitor Characteristics
Quantity
(ESR) Equivalent
Series Resistance
85°C Maximum Ripple
Current(Irms)
Physical
Size(mm)
Input Output
Bus Bus
Vendor Number
Panasonic
35V
FC
35V
50V
Un ited
35V
Chemi-con
50V
LXV/LXZ/
10V
FX/FS
20V
Nichicon
35V
PL/
25V
PM
35V
Panasonic
35V
FC
35V
Surface Mtg
35V
Oscon SS/SV
10V
10V
680µF
560µF
680µF
680µF
680µF
390µF
150µF
560µF
820µF
560µF
330µF
1000µF
470µF
330µF
330µF
0.043Ω
0.038Ω
0.048Ω
0.038Ω
0.048Ω
0.030Ω
0.024Ω
0.048Ω
0.049Ω
0.0048Ω
0.065÷2Ω
0.038Ω
0.043Ω
0.025Ω
0.025Ω
1690mA
1655mA
1835mA
1660mA
1840mA
3080mA
3200mA
1360mA
1340mA
1360mA
>1205mA
2000mA
1690mA
>3500mA
>3800mA
16x15
1
12.5x20
1
16x20
1
12.5x20
1
16x20
1
8x10.5
N/R
8x10.5
4
16x15
1
16x15
1
16x15
1
12.5x16.5
2
18x16.5
1
16x16.5
10.0x10.5
N/R
10.3x10.3
N/R
AVX
Tantalum
TPS
10V
330µF
10V
220µF
0.060÷2Ω
0.060÷2Ω
>2500mA
>3000mA
7.3Lx
N/R
4.3Wx
N/R
Kemet
T510
T495
Sprague
594D
10V
330µF
0.033Ω
10V
220µF
0.07Ω÷2 =0.035Ω
10V
330µF
0.045Ω
1400mA
>2000mA
2350mA
7.3Lx5.7W N/R
x 4.0H
N/R
7.3Lx
6.0Wx
N/R
4.1H
N/R –Not recommended. The voltage rating does not meet the minimin operating limits.
1
EEUFC1V681S
1
EEUFC1V561S
1
EEUFC1H681
1 LXZ35VB681M112X20LL
1
LXZ50VB681M16X20LL
1
10FX390M
2
20FX150M
1
UPL1V561MHH6
1
UPL1E821MHH6
1
UPM1V561MHH6
2
EEVFC1V331LQ
1
EEVFC1V1021N
1
EEVFC1V471N
1
1
10SS330M
10SV330M
Surface Mount(SV)
2
TPSV337M010R0060
2
TPSV227M010R0060
1
T510X337M010AS
2
T495X227M010AS
1
594D337X0010R2T
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