PT7671 Datasheet, PDF (6/9 Pages) Texas Instruments – 30-A Programmable Integrated Switching Regulator

Application Notes
PT7670 Series
Capacitor Recommendations for the PT7670
Series of 30-A Switching Regulators
Input Capacitor:
The recommended input capacitor is determined by a
minimum of 1,500 µF of capacitance with a ripple cur-
rent rating of 1.1 Arms.
Ripple current and <100 mΩ equivalent series 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 twice 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 capacitors is less than 100 mΩ.
Electrolytic capacitors have marginal ripple performance
at frequencies greater than 400 kHz 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 2-1.
Tantalum Capacitors( Optional Output Capacitors)
Tantalum type capacitors can be used for the output but
only the AVX TPS, Sprague 593D/594/595, 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
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 2-1 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
(at 100 kHz) are critical parameters necessary to insure both
optimum regulator performance and long capacitor life.
Table 2-1: Input/Output Capacitors
Capacitor Vendor/
Series
Capacitor Characteristics
Quantity
Panasonic FK (SMT)
FC (Radial)
United Chemi -Con
LXZ
FX
Nichicon PL Series
NX (SMT)
Os-con SP (Radial)
SVP (SMT)
AVX Tanatalum
TPS- Series
Sprague Tantalum
595D/594D
Kemet Tantalum
T510/T495 (SMT)
Sanyo Poscap
TPB (SMT)
Working
Voltage
25 V
35 V
16 V
16 V
Value(µF) (ESR) Equivalent
Series Resistance
2200
330
470
1500
0.038 Ω
0.080 Ω
0.090 Ω
0.043 Ω
Maximum Ripple
Current @105 °C
(Irms)
1800 mA
850 mA
755 mA
1690 mA
Physical Size
(mm)
16×16.5
10×10.2
10×12.5
16×15
Input
Bus
Output
Bus
Vendor Number
1
1 EEVFK1E222M
—
1 EEVFK1V331P
—
1 EEUFC1C471
1
1 EEUFC1C152S
25 V
16 V
10 V
25 V
10 V
10 V
10 V
10 V
10 V
10 V
10 V
10 V
10 V
10 V
10 V
330
1500
680
390
1500
330
470
330
330
330
330
680
330
220
220
0.090 Ω
0.038 Ω
0.015 Ω
0.080 Ω
0.050 Ω
0.024 Ω
0.015 Ω
0.017 Ω
0.10 Ω
0.06 Ω
0.045÷4 =0.011 Ω
0.09 Ω
0.035 Ω
0.07÷2 =0.035 Ω
0.04 Ω
760 mA
1660 mA
4735 mA
720 mA
1330 mA
3770 mA
>4510 mA
>3950 mA
1414 mA
1826 mA
>4500 mA
>1510 mA
2000 mA
>2000 mA
3000 mA
10×12.5
—
12.5×20
1
10×10.5
2
12.5×15
—
16×15
1
10×8
5
10×10.5
3
9×12×8.3
4
7.3L×4.3W
5
×4.1H
5
7.3L×5.7W
5
×4.0H
2
4.3W×7.3L
5
×4.0H
6
7.2L ×4.3W
6
×3.1H
1 LXZ25VB331M10X12LL
1 LXZ16VB152M12X20LL
1 10FX680M
1 UPL1E391MHH6
1 UPL1A152MHH6
1 PNX1A331MCR1GS
1 10SP470M
1 10SVP330M
1 TPSV337M010R0100
1 TPSV337M010R0060
1 594D337X0010R2T
1 595D687X0010R2T
1 510X337M010AS
2 T495X227M010AS
2 10TPB220M
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