SLTS102A Datasheet, PDF (4/8 Pages) Texas Instruments – 14-A 12V-Input Adjustable Integrated Switching Regulator

Application Notes
PT6721/22 & PT6725 Series
Capacitor Recommendations for the 12V-Input
PT6721/22 and PT6725 Series of ISRs
Input Capacitors
The recommended input capacitor(s) is determined by
1.6Arms minimum ripple current rating and 1,000µF mini-
mum capacitance. Ripple current and Equivalent Series
Resistance (ESR) values are the major considerations along
with temperature when selecting the proper capacitor.
The tantalum capacitors listed below cannot be used on
the input bus since they are not rated for 12V operation.
Output Capacitors
The minimum required output capacitance is 330µF with a
maximum ESR less than or equal to 50mΩ. Failure to
observe this requirement may lead to regulator instability
or oscillation. Electrolytic capacitors have poor ripple
performance at frequencies greater than 400kHz, but
excellent low frequency transient response. Above the
ripple frequency ceramic decoupling capacitors are nec-
essary to improve the transient response and reduce any
microprocessor high frequency noise components apparent
during higher current excursions. Preferred low ESR type
capacitor part numbers are identified in the Table 1 below.
Tantalum Characteristics
Tantalum capacitors are recommended on the output bus
but only AVX TPS Series, Sprague 593D/594/595 Series,
or Kemet T495/T510 Series. These capacitors are recom-
mended over other types due to their higher surge current,
excellent power dissipation and ripple current ratings. As a
caution, the TAJ Series by AVX is not recommended. This
series exhibits considerably higher ESR, reduced power
dissipation and lower ripple current capability. The TAJ
Series is also less reliable compared to the TPS series when
determining power dissipation capability.
Capacitor Table
Table 1 identifies the characteristics of capacitors from a
number of vendors with acceptable ESR and ripple cur-
rent (rms) ratings. The suggested minimum quantities
per regulator for both the input and output buses are
identified.
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 the
critical parameters are necessary to insure both optimum
regulator performance and long capacitor life.
Table 1 Capacitors Characteristic Data
Capacitor Vendor/
Series
Capacitor Characteristics
Quantity
Panasonic
FC (Radial)
Working Value(µF) (ESR) Equivalent
Voltage
Series Resistance
35V
680
25V
1000
25V
1000
0.043Ω
0.038Ω
0.038Ω
105°C Maximum
Ripple
Current(Irms)
1655mA
1655mA
1690mA
Physical
Size(mm)
12.5×20
12.5×20
16×15
FC/FK (Surface Mount)
50V
25V
35V
United Chemi-con
35V
LXV Series
35V
16V
Nichicon
35V
PL Series
25V
PM Series
35V
Os-con:
SS
10V
SV (surface Mount)
10V
AVX Tantalum
10V
TPS (Surface Mount)
10V
Kemet Tantalum
10V
T510/T495 Series
10V
(Surface Mount)
Sprague Tantalum
10V
594D Series
(Surface Mount)
1000
1000
470
680
1000
470
680
1200
1000
0073Ω
0.038Ω
0.043Ω
0.034Ω
0.038Ω
0.084Ω÷2 =0.042Ω
0.036Ω
0.039Ω
0.034Ω
1610mA
2000mA
1690mA
1690mA
1630mA
825mA (×2)
1660mA
1600mA
1770mA
330
0.025Ω
330
0.020Ω
330
0.1Ω÷2 =0.05Ω
330
0.06Ω÷2 =0.03Ω
3500mA
3800mA
>2500mA
>3000mA
330
0.033Ω
220
0.07Ω÷2 =0.035Ω
1400mA
>2000mA
330
0.045Ω
2360mA
16×16.5
18×16.5
16×16.5
12.5×25
16×20
10×16
12.5×25
18×15
16×20
10×10.5
10.3×10.3
7.3L
×5.7W
×4.1H
4.3W
×7.3L
×4.0H
7.2L
×6W
×4.1H
Note: (N/R -Not recommended) The 10V-rated tantalum capacitors cannot be used on the input bus.
Input
Bus
Output
Bus
Vendor Part Number
2
1 EEUFC1V681
1
2 EEUFC1E102
1
1 EEUFC1E102S
1
1 EEVFK1H102M
1
1 EEVFC1E102N
2
1 EEVFC1V471N
2
1 LXV35VB680M12X25LL
1
1 LXV35VB102M16X20LL
2
1 LXV16VB471M10X16LL
2
1 UPL1V681MHH
1
1 UPL1E122MHH6
1
1 UPM1V102MHH6
N/R(1)
N/R(1)
N/R(1)
N/R(1)
1 10SS330M (Vo <5V)
1 10SV330 (Vo <5V)
2 TPSE337M010R0100
2 TPSV337M010R0060
N/R(1)
N/R(1)
1 510X337M010AS
2 T495X227M0100AS
N/R(1)
1 594D337X0010R2T
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