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Matters needing attention in application of tantalum capacitor
Matters needing attention in application of tantalum capacitor
In order to make the tantalum electrolytic capacitor in the most stable quality and give full play to its performance, it is necessary to use the appropriate method, please ensure that before use.
The performance of recognition of capacitor using conditions and regulations, must comply with the required specifications on the conditions, such as the use of the conditions do not comply with the provisions.
Please specify the terms and conditions of the company to negotiate with the company.
1 design circuit
1.1. use voltage
The fault of the capacitor is affected by the ratio of the voltage to the rated voltage. When designing the actual circuit, please take into account the requirements
Depending on the proper reduction of voltage.
The use of a low impedance circuit, please use the setting voltage at rated voltage of 1 / 3, the use of other circuits, please use the voltage set at rated voltage 2 / 3.
The parallel use in low impedance circuit, will increase the risk of DC surge current failure at the same time, please note that the shunt capacitor in storage
Charge stored in the other capacitor.
The tantalum capacitors in the circuit, we should control the instantaneous large current of capacitor series resistance to impact, suggestions to alleviate the impact. please
A protective resistor of 3 / V is connected in series to the capacitor to limit the current to the 300mA, which can not be inserted to protect the resistor,
Please use the voltage below 3 / 1 of the rated voltage.
1.2 reverse voltage
Tantalum capacitor is a polar capacitor, so please do not apply reverse voltage, and can not use only the AC circuit.
- if necessary, allow the reverse voltage applied amount in a short period of time, its value is:
25 C: less than 10%UR or 1V (for small)
85 C: less than 5%UR or 0.5V (for small)
If the capacitor will be used for a long time in a reverse circuit, please use the non polar tantalum capacitors.
The silver shell of non solid electrolyte tantalum capacitors cannot withstand reverse voltage.
Prohibit the use of multimeter resistance profile of a circuit or capacitor tantalum capacitor itself without polarity test - principle.
In the measurement process, such as made of tantalum capacitors under a reverse voltage should not have, please the capacitor scrapped, even if
The electrical parameters are still qualified.
1.3 ripple voltage
Please use the allowable ripple voltage in the capacitor.
- use, DC bias and AC voltage peak and shall not exceed the rated voltage of capacitor value.
The AC and DC bias and negative peak value of the capacitor does not exceed the allowable value of reverse voltage.
The ripple current generated by the active power loss of tantalum capacitors, capacitors and its temperature rise caused by thermal breakdown failure probability
Large, therefore it is necessary to limit the power loss through the capacitor ripple current or capacitance.
1.4 using ambient temperature
Please use the temperature range in the provisions of the capacitor.
The use of temperature more than 85 DEG C, please refer to the voltage derating used as voltage, as shown below.
The temperature characteristic is one of the main electrical properties of tantalum capacitors, so when using the temperature changes significantly, please in the use of temperature on,
The lower limit to confirm the circuit characteristics, the following figure for example, different varieties please apply for technical information.
11.5 frequency characteristic
Frequency in the 10KHz area, the electrical characteristics of the capacitor changes significantly, so when using the high frequency circuit, please confirm the circuit characteristics,
As shown in the following example, different varieties, please apply for technical information.
1.6 reliability
The failure rate of the tantalum capacitor varies according to the conditions of its application (such as ambient temperature, applied voltage, circuit resistance, use circuit, etc.)
In the same, so please choose the appropriate products after the full discussion of the conditions of use.
The general design of the capacitor, in 85 C continuous rated voltage is applied to 1000 hours of failure rate as a benchmark, in the actual circuit
It is often used in the actual use of the problem of preventing the peak shock of the voltage or current and the ripple current or other unexpected electric shock.
Drop design is necessary, it is recommended to reduce the amount to 65%VR.
The use of safety equipment to pay attention to, in order to prevent the short circuit in use, open circuit phenomenon. Therefore, the design of the full note
To ensure the safety of the following.
A. design protection circuit, protection device, system use, to ensure safety.
B. design of redundant circuits, so that it becomes a single failure even when a single failure, it does not cause the entire device failure system.
2 installation
When the capacitor is installed on the printed circuit board, the load of mechanical shock or thermal shock will lead to the deterioration of electrical characteristics,
Short-circuit and so on, so please confirm the actual installation conditions and then use.
2.1 use - Measurement
- please note that don't apply too much force when in use, the electroplating peeling body or lead terminal of the capacitor is injured.
The fall or has installed a capacitor once again please do not use.
- after installation, please do not Processing capacitors or bending terminal etc..
Lead - capacitor (including chip tantalum container electric outlet), in use process measurement. Please pay attention to avoid direct contact with bare hands,
In order to avoid perspiration, oil pollution caused by bad weldability.
2.2 circuit board cleaning
When cleaning, remove the welding flux in the same time, the rapid removal of acid, alkali, etc., can not make the residue, cleaning temperature should be in the
50 degrees below, ultrasonic, steam impregnation and other total time should be less than 5 minutes, and please note that, according to the conditions of ultrasonic cleaning is not
The same, will cause the terminal to break off.
2.3 welding
2.3.1 with iron welding
The use of iron (below 30W), the tip of the soldering iron temperature of 350 DEG C, the use of time should be less than 4 seconds, and pay attention to the iron tip
No
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