
CAPACITOR RECOMMENDATIONS FOR THE PTR08100W POWER MODULE
Capacitor Technologies
SLTS284E – AUGUST 2007 – REVISED APRIL 2009 ....................................................................................................................................................... www.ti.com
Table 2. Calculated RSET Resistor Values
VO Req'd
RSET (k)
VO Req'd
RSET(k)
VO Req'd
RSET(k)
(V)
0.6
131
2.3
0.692
4.0
0.347
0.7
10.8
2.4
0.653
4.1
0.337
0.8
5.66
2.5
0.619
4.2
0.328
0.9
3.83
2.6
0.588
4.3
0.319
1.0
2.89
2.7
0.560
4.4
0.310
1.1
2.32
2.8
0.535
4.5
0.302
1.2
1.94
2.9
0.512
4.6
0.295
1.3
1.67
3.0
0.491
4.7
0.288
1.4
1.46
3.1
0.471
4.8
0.281
1.5
1.30
3.2
0.453
4.9
0.274
1.6
1.17
3.3
0.436
5.0
0.268
1.7
1.07
3.4
0.421
5.1
0.262
1.8
0.978
3.5
0.406
5.2
0.256
1.9
0.903
3.6
0.393
5.3
0.251
2.0
0.839
3.7
0.380
5.4
0.246
2.1
0.783
3.8
0.368
5.5
0.241
2.2
0.735
3.9
0.357
Electrolytic Capacitors
When using electrolytic capacitors, high-quality, computer-grade electrolytic capacitors are recommended.
Aluminum electrolytic capacitors provide adequate decoupling over the frequency range of 2 kHz to 150 kHz,
and are suitable when ambient temperatures are above -20°C. For operation below -20°C, tantalum,
ceramic, or OS-CON type capacitors are required.
Ceramic Capacitors
The performance of aluminum electrolytic capacitors is less effective above 150 kHz. Multilayer ceramic
capacitors have a low ESR and a resonant frequency higher than the bandwidth of the regulator. They can
be used to reduce the reflected ripple current at the input as well as improve the transient response of the
output.
Tantalum, Polymer-Tantalum Capacitors
Tantalum type capacitors may only used on the output bus, and are recommended for applications where the
ambient operating temperature is less than 0°C. The AVX TPS series and Kemet capacitor series are
suggested over many other tantalum types due to their lower ESR, higher rated surge, power dissipation,
and ripple current capability. Tantalum capacitors that have no stated ESR or surge current rating are not
recommended for power applications.
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