There are electrolytic capacitors in modern electronic products, and its life is related to the service life of our electronic products. So how do we make simple choices when designing products?
Step 1: Temperature measurement: First, we use an electrolytic capacitor with qualified electrical parameters (voltage and capacity meet the circuit requirements) in the product. Then the product is electrified, and the temperature of the electrolytic capacitor is measured and recorded after working at ambient temperature for 1 hour. For example, we test the working temperature of electrolytic capacitor at 25℃ and 72℃.
The second step is to select the type: how many years is the product life? For example, a life span of five years. So how do we choose? The core life rule is that the life of electrolytic capacitor will be doubled for every 10℃ drop in temperature.
Specific understanding according to the following examples, there are two ways:
1. Backward calculation method: Calculate whether the electrolytic capacitor with a life of 6000H at 105℃ can meet the following requirements:
The life at 105℃ is 6000H,
The service life at 95℃ is 6000*2=12000H,
The service life at 85℃ is 12,000 * 2 = 24,000 h,
The service life at 75℃ is 24,000 * 2 = 48,000 h,
According to the above test, the temperature is 72℃, so we can't calculate the life down any more. Let's see if it meets the following requirements:
48000H/24H=2000 days;
2000 days /365 days =5.479 years,
Therefore, the life span is large and the difference is not big, so the choice is reasonable.
2. Forward deduction method: 5 years *365 days =1825 days,
1825 days *24H=43800H,
82℃ needs 43800H/2=21900H,
92℃ requires 21900H/2=10950H,
102℃ needs 10950H/2=5475H,
Therefore, the electrolytic capacitor should be 105℃5475H, and the actual specification is 105℃6000H (it can only be higher than the
demand and meet the actual specification).
In short, there is no need for complicated formulas when selecting electrolytic capacitors, just remember that the core life rule is that
the life of electrolytic capacitors will double every 10℃ drop in temperature. Of course, in the design, it is necessary to leave a pre-quantity,
and the parameters can only be high but not low.
