PT7615 Datasheet, PDF (4/7 Pages) Texas Instruments – 20-A Low-Voltage Programmable Integrated Switching Regulator

Application Notes
PT7708/09, PT7615, PT7742/PT7743
Capacitor Recommendations for 20-A
Programmable Switching Regulators
Input Capacitors
The recommended input capacitance is determined by the
1.4 ampere minimum ripple current rating and 1500µF
minimum capacitance. Capacitors listed below must be
rated for a minimum of two times (2×) the input voltage
with +5V operation. Ripple current and ≤100mΩ ESR
(equivalent series resistance) values are the major consider-
ations along with temperature when selecting the proper
capacitor.
Output Capacitors
The minimum required output capacitance is 330µF with a
maximum ESR less than or equal to 100mΩ. 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 with a minimum 10-V rating are
recommended on the output bus, but only the AVX TPS
Series, Sprague 594/595 Series, or Kemet T495/T510
Series. These AVX, Sprague, and Kemet capacitors are
specified 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 current
(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 comparible specifications.
The RMS ripple current rating and ESR (Equivalent Series
Resistance at 100kHz) are the critical parameters necessary
to insure both optimum regulator performance and long
capacitor life.
Table 1 Capacitors Characteristic Data
Capacitor
Vendor/
Series
Capacitor Characteristics
Quantity
Working Value(µF) (ESR) Equivalent
Voltage
Series Resistance
105°C Maximum
Ripple
Current(Irms)
Physical
Size(mm)
Input
Bus
Output
Bus
Vendor Number
Panasonic
FC (SMT)
16V
2200
35V
330
0.038Ω
0.065Ω
2000mA
1205mA
18x16.5
1
12.5x16.5
1 EEVFC1C222N
1 EEVFC1V331LQ
FC (Radial)
10V
16V
United
25V
Chemi -Con
16V
LFVSeries
16V
Nichicon
10V
PL Series
10V
PM Series
25V
560
1800
330
2200
470
680
1800
330
0.090Ω
0.032Ω
0.084Ω
0.038Ω
0.084Ω÷2 =0.042Ω
0.090Ω
0.044Ω
0.095Ω
755mA
2000mA
825mA
1630mA
825mA x2
770mA
1420mA
750mA
10x12.5
1 EEUFC1A561
18x15
1
1 EEUFC1C182S
10x16
16x20
10x16
1 LXV25VB331M10X16LL
1
1 LXV16VB222M16X20LL
1 LXV16VB471M10X16LL
10x15
16x15
10x15
1 UPL1A681MHH6
1
1 UPL1A182MHH6
1 UPL1E331MPH6
Oscon
SS (Radial)
10V
SV (SMT)
10V
AVX
10V
Tanatalum
10V
TPS- Series
Sprague
10V
Tantalum
10V
595D/594D
Kemet
10V
Tantalum
T510/T495
10V
Series
Sanyo Poscap
10V
TPB
330 0.025Ω÷4 =0.006Ω
330
0.02Ω÷4 =0.005Ω
330
0.1Ω÷5 =0.02Ω
330
0.06Ω
330 0.045Ω÷4 =0.011Ω
680
0.09Ω
330
0.035Ω
220
0.07Ω÷2 =0.035Ω
220
0.04Ω
>9800mA
>9800mA
3500mA
1826mA
>4500mA
>1660mA
2000mA
>2000mA
3000mA
10x10.5
10.3x12.6
7.3Lx
4.3Wx
4.1H
7.3L x
5.7W x
4.0H
4.3Wx7.3L
x4.0H
7.2L x
4.3W x
3.1H
4
N/R 10SS330M
4
(Note) 10SV330M
5
1 TPSV337M010R0100
5
1 TPSV337M010R0060
5
1 594D337X0010R2T
2
1 595D687X0010R2T
(Surface Mount)
5
1 510X337M010AS
6
2 T495X227M010AS
(Surface Mount)
6
2 10TPB220M
(Surface Mount)
Note: (N/R) is not recommended for this application, due to extremely low Equivalent Series Resistance (ESR)
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