Reduce Power dissipation

[Jieun]

in LNA
How can I reduce power dissipation?
And How can I calculate power dissipation?

 

[Audioguru]

Power dissipation is the voltage across something times the current through it. To reduce the amount of heat then simply reduce the voltage, the current or both.

 

[optoroute]

in LNA
How can I reduce power dissipation?
And How can I calculate power dissipation?

There are some ways to reduce power dissipation, please see it as below:

1. Use a Proper DC Input Source
A low voltage input reduces the power dissipation. In order to charge the single-cell Li+ battery, we need a well regulated 4.2V±1% or 4.1V±1% (depending on battery chemistry) output. The input voltage needs to be higher to cover the voltage drops between the battery positive terminal and the input DC source. Figure 1 shows these for a typical charger.

2. Optimize Charge Current and Power Dissipation
Figure 3 shows the circuit used for testing. It is a linear charger with a 500mA charge current and a 6 hours timer limit.


Conclusion
We can deliver a safe and reliable linear charger for a single-cell Li+ battery by optimizing the DC input source, the charge current, and the power dissipation with proper heatsinking method. Figure 4 shows an actual test result using the MAX1898 charger with a 4.2V, 900mA Li+ cell and a regulated 5V/1A MAX5021 AC adapter.


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