LMZ31506_15 Datasheet, PDF (12/35 Pages) Texas Instruments – 6A SIMPLE SWITCHER® Power Module with 2.95V-14.5V Input and Current Sharing in QFN Package

LMZ31506
SNVS993 – JUNE 2013
CAPACITOR RECOMMENDATIONS FOR THE LMZ31506 POWER SUPPLY
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Capacitor Technologies
Electrolytic, Polymer-Electrolytic Capacitors
When using electrolytic capacitors, high-quality, computer-grade electrolytic capacitors are recommended.
Polymer-electrolytic type capacitors are recommended for applications where the ambient operating temperature
is less than 0°C. The Sanyo OS-CON capacitor series is suggested due to the lower ESR, higher rated surge,
power dissipation, ripple current capability, and small package size. Aluminum electrolytic capacitors provide
adequate decoupling over the frequency range of 2 kHz to 150 kHz, and are suitable when ambient temperatures
are above 0°C.
Ceramic Capacitors
The performance of aluminum electrolytic capacitors is less effective than ceramic capacitors 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
Polymer-tantalum type capacitors are recommended for applications where the ambient operating temperature is
less than 0°C. The Sanyo POSCAP series and Kemet T530 capacitor series are recommended rather than many
other tantalum types due to their lower ESR, higher rated surge, power dissipation, ripple current capability, and
small package size. Tantalum capacitors that have no stated ESR or surge current rating are not recommended
for power applications.
Input Capacitor
The LMZ31506 requires a minimum input capacitance of 100 μF of ceramic and/or polymer-tantalum capacitors.
The ripple current rating of the capacitor must be at least 450 mArms. Table 4 includes a preferred list of
capacitors by vendor.
Output Capacitor
The required output capacitance is determined by the output voltage of the LMZ31506. See Table 3 for the
amount of required capacitance. The required output capacitance must be comprised of all ceramic capacitors.
When adding additional non-ceramic bulk capacitors, low-ESR devices like the ones recommended in Table 4
are required. The required capacitance above the minimum is determined by actual transient deviation
requirements. See Table 5 for typical transient response values for several output voltage, input voltage and
capacitance combinations. Table 4 includes a preferred list of capacitors by vendor.
Table 3. Required Output Capacitance
V_OUT RANGE (V)
MIN
MAX
0.6
< 0.8
0.8
< 1.2
1.2
< 3.0
3.0
< 4.0
4.0
5.5
MINIMUM REQUIRED C_OUT (µF)
400 µF ceramic
300 µF ceramic
200 µF ceramic
100 µF ceramic
47 µF ceramic
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