PT7761-5V_09 Datasheet, PDF (5/9 Pages) Texas Instruments – 40-A Programmable Integrated

Application Notes
PT7761, PT7769
Capacitor Recommendations for the
PT7761 Integrated Switching Regulator
Input Capacitors
The recommended input capacitance is determined by
1.4 ampere minimum ripple current rating and 1500µF
minimum capacitance. Capacitors listed below must be
rated for a minimum of 2x the input voltage with +5V
operation. Ripple current and ≤100mΩ Equivalent Series
Resistance (ESR) values are the major considerations 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 perfor-
mance at frequencies greater than 400kHz, but excellent low
frequency transient response. Above the ripple frequency
ceramic decoupling capacitors are necessary 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.
Table 1 Capacitors Characteristic Data
Tantalum Characteristics
Tantalum capacitors with a minimum 10V 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 than the TPS series when deter-
mining 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 regu-
lator for both the input and output buses are identified.
This is not an extensive capacitor list. The table below is a
selection guide for input and output capacitors. Other capacitor
vendors are available with comparable RMS ripple current rating
and ESR (Equivalent Series Resistance at 100kHz). These
critical parameters are necessary to insure both optimum regulator
performance and long capacitor life.
Capacitor
Vendor/
Series
Panasonic
FC
Surface Mtg
FA
United
Chemi -Con
LFVSeries
Nichicon
PL Series
PM Series
Oscon SS
SV
Capacitor Characteristics
Working
Voltage
16V
35V
10V
16V
25V
16V
16V
10V
10V
25V
10V
10V
Value(µF)
(ESR) Equivalent
Series Resistance
2200
330
680
1800
330
2200
470
680
1800
330
330
330
0.038Ω
0.065Ω
0.090Ω
0.032Ω
0.084Ω
0.038Ω
0.084Ω÷2 =0.042Ω
0.090Ω
0.044Ω
0.095Ω
0.025Ω÷4 =0.006Ω
0.02Ω÷4 =0.005Ω
105°C Maximum
Ripple
Current(Irms)
2000mA
1205mA
755mA
2000mA
825mA
1630mA
825mA x2
770mA
1420mA
750mA
>9800mA
>9800mA
Physical
Size(mm)
18x16.5
12.5x16.5
10x12.5
18x15
10x16
16x20
10x16
10x15
16x15
10x15
10x10.5
10.3x12.6
AVX
10V
Tanatalum
10V
TPS- Series
Sprague
10V
Tantalum
10V
595D/594D
Kemet
10V
Tantalum
T510/T495
10V
Series
Sanyo Poscap
10V
TPB
330
0.1Ω÷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
3500mA
1826mA
>4500mA
>1660mA
2000mA
>2000mA
3000mA
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
Note: (N/R) is not recommended for this application, due to extremely low Equivalent Series Resistance (ESR)
Quantity
Input
Bus
Output
Bus
Vendor Number
1
1 EEVFC1C222N
1 EEVFC1V331LQ
1 EEUFA1A681
1
1 EEUFA1C182A
1 LXV25VB331M10X16LL
1
1 LXV16VB222M16X20LL
1 LXV16VB471M10X16LL
1 UPL1A681MHH6
1
1 UPL1A182MHH6
1 UPL1E331MPH6
4
N/R 10SS330M
4
(Note) 10SV330M
(Surface Mount)
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)
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