2.7V 100F super capacitor
Working temperature range
Rated discharge capacitance
High temperature load
High temperature storage
How to choose / super capacitor edit
Two main applications for supercapacitors: high power pulse applications and instantaneous power retention. Features of high-power pulse applications: instantaneous flow to load high current; characteristics of instantaneous power retention applications: require continuous power supply to the load, typically for a few seconds or minutes. A typical application for instantaneous power retention: the reset of the disk drive head during a power outage. Different applications have different parameters for the parameters of the supercapacitor. The high power pulse application utilizes a small internal resistance (R) of the supercapacitor, while the instantaneous power retention is a large electrostatic capacity (C) using the supercapacitor.
Two calculation formulas and application examples are provided below:
C(F): the nominal capacity of the supercapacitor;
R (Ω): the nominal internal resistance of the supercapacitor;
ESR (Ω): equivalent series resistance at 1KZ;
Uwork(V): normal operating voltage in the circuit
Umin(V): The minimum voltage required to operate the device;
t(s): the hold time required in the circuit or the pulse duration in the pulse application;
Udrop(V): The total voltage drop at the end of a discharge or high current pulse;
I(A): load current;
Instantaneous power retention application
An approximate calculation formula for the capacitance of the supercapacitor, which is based on maintaining the required energy = supercapacitance to reduce energy.
Energy required during the hold period = 1/2I (Uwork + Umin) t;
Supercapacitor reduces energy = 1/2C (Uwork2 - Umin2),
Therefore, its capacity can be obtained (ignoring the voltage drop caused by IR) C=I(Uwork+ Umin)t/(Uwork2 -Umin2)
Assume that the tape drive operates at 5V and the safe operating voltage is 3V. If the DC motor requires 0.5A for 2 seconds (can work safely), then the capacity can be at least 0.5 F according to the above formula.
Because the voltage of 5V exceeds the nominal operating voltage of the single capacitor. Thus, the two capacitors can be connected in series. If two identical capacitors are connected in series, then each voltage is its nominal voltage of 2.5V.
If we choose a capacitor with a nominal capacity of 1F, the two strings are 0.5F. This choice does not provide sufficient margin given the -20% capacity deviation of the capacitor. Capacitors with a nominal capacity of 1.5F can be selected to provide 1.5F/2 = 0.75F. Consider a -20% capacity deviation with a minimum of 1.2F/2 = 0.6F. This supercapacitor provides ample safety margin. After the high current pulse, the tape drive is switched to the low current mode of operation, using the excess energy of the supercapacitor.
In this example, the voltage equalization circuit ensures that each cell does not exceed its rated voltage.