PT6520 Datasheet, PDF (7/12 Pages) Texas Instruments – 8-A 5-V/3.3-V Input Adjustable ISR with Short-Circuit protection

Application Notes
PT6520 Series
Capacitor Recommendations for the PT6520 Series of
Integrated Switching Regulators
Input Capacitors:
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 temperature, when designing with different
types of capacitors. Tantalum capacitors have a recom-
mended minimum voltage rating of 2× the maximum
DC voltage + AC ripple. This is necessary to insure
reliability for input voltage bus applications
Output Capacitors:
The ESR of the required capacitor (C_out) 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.
Tantalum Capacitors
Tantalum type capacitors may be used for the output but
only the AVX TPS series, Sprague 593D/594/595 series
or Kemet T495/T510 series. These capacitors are rec-
ommended 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 dissipation, 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 appli-
cations 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 cur-
rent (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
(ESR) Equivalent
Series Resistance
85°C Maximum Ripple
Current(Irms)
Quantity
Physical
Size(mm)
Input Output
Bus Bus
Vendor Number
Panasonic
25V
FC
35V
35V
United
16V
Chemi-Con
35V
LXV/FS/
10V
LXZ
20V
Nichicon
PL/ PM
35V
35V
50V
Panasonic
10V
FC
35V
(Surface Mtg)
16V
Oscon- SS
10V
SV
10V
20V
560µF
390µF
330µF
330µF
470µF
330µF
150µF
560µF
330µF
470µF
1000µF
330µF
330µF
330µF
330µF
150µF
0.0065Ω
0.065Ω
0.117Ω
0.120Ω
0.052Ω
0.025Ω
0.030÷2 Ω
0.048Ω
0.065÷2 Ω
0.046Ω
0.043Ω
0.065Ω
0.150Ω
0.025Ω
0.025Ω
0.024÷2 Ω
1205mA
1205mA
555mA
555mA
1220mA
3500mA
3200mA
1360mA
1020mA
1470mA
1205mA
1205mA
670mA
>3500mA
>3800mA
3600mA
12.5x15
1
12.5x15
2
8x11.5
N/R
8x12
N/R
10x20
1
10x10.5
1
10x10.5
2
16x15
1
12.5x15
1
18x15
1
12x16.5
1
12.5x16
1
10x10.2
N/R
10.0x10.5
1
10.3x10.3
1
10.3x10.3
2
AVX
Tantalum
TPS
Kemet
T510/
T495
Sprague
594D
10V
330µF
10V
330µF
10V
220µF
0.100÷2 Ω
0.100÷2 Ω
0.095Ω
10V
330µF
0.033Ω
10V
220µF
0.07Ω÷2 =0.035Ω
10V
330µF
10V
220µF
0.045Ω
0.065Ω
>2500mA
>3000mA
>2000mA
1400mA
>2000mA
2350mA
>2000mA
7.3Lx
2
4.3Wx
2
4.1H
2
7.3Lx5.7W
2
x 4.0H
2
7.3Lx
6.0Wx
4.1H
2
2
N/R –Not recommended. The ripple current rating and ESR does not meet the requirements.
1 EEUFC1E561S
1 EEUFC1V391S
1 EEUFC1C331
1 LXZ16VB331M8X12LL
1 LXZ35VB471M10X20LL
1 10FS330M
2 20FS150M
1 UPL1V561MHH6
1 UPL1V331MHH6
1 UPM1H4711MHH6
1 EEVFC1A102LQ
1 EEVFC1V331LQ
1 EEVFC1C331P
1 10SS330M
1 10SV300M
2 20SV150M
SV= Surface Mount
1 TPSV337M010R0100
1 TPSV337M010R0060
2 TPSV227M0105R0100
1 T510X337M010AS
2 T495X227M010AS
1 4D337X0010R2T
2 594D227X0010D2T
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