button battery 2032

Design of button battery 2032 over-discharge protection circuit

In the solar power supply system, in order to ensure uninterrupted power supply, the most common method is to combine solar cells with batteries to form an uninterruptible power supply system; some special instruments or meters require normal operation when the city power is off, and batteries are also used as backup power sources. button battery 2032 over-discharge is the direct cause of premature button battery 2032 damage or scrapping, and it also directly affects the service life of the instrument.

In order to protect the button battery 2032 from damage caused by over-discharge, the button battery 2032 discharge termination voltage needs to be set according to the load conditions to protect the button battery 2032, extend the button battery 2032 life and the trouble-free operation time of the instrument. This article takes the power supply of the radio frequency card vending machine of Cape Company as an example to briefly introduce the design of the button battery 2032 over-discharge protection circuit.

According to the relationship between button battery 2032 life and discharge depth and the relationship between button battery 2032 voltage and discharge rate and discharge depth, combined with the actual load of the equipment, the button battery 2032 discharge termination voltage is determined and the button battery 2032 discharge protection circuit is designed. The relationship between button battery 2032 life (number of cycles) and discharge depth is shown in the relationship between discharge voltage and discharge rate. U2A and peripheral resistors, capacitors, etc. form a monostable circuit to eliminate key jitter, U2B forms a bistable circuit to drive TPS2015 to control the power on and off; the LM393 voltage comparator and peripheral circuits form a low-voltage detection circuit; the TL431 reference regulator forms a 2.5V voltage source; resistors RS, R9 and Vi form a voltage sampling circuit. When the sampling voltage WCR8+R9+V1) is lower than 2.5V, the red LED will light up for warning; when the button battery 2032 voltage Vhr (R9+V1VCR8+R9+V1) is also lower than, IM393CU3B) outputs a high level to control the set end of the bistable circuit composed of CD4013O1B), so that the output of the bistable circuit is set to 1, and the electronic switch TPS2015 is controlled to forcibly cut off the load. At the same time, the low-voltage detection circuit composed of LM393 loses power and exits work, and will not trigger the electronic switch by mistake. Even if the button battery 2032 power is sufficient through charging, SW-PB must be pressed manually to re-power the power supply.

Since a 6.3V button battery 2032 is used as a backup power in the system, the main parameters of TL431 are shown in Table 1, and its basic working circuit is shown in Table 1.

1 Main parameters of voltage reference source TL431 Project Parameter Maximum input voltage/V Minimum operating current/mA Maximum operating current/mA Reference voltage/V Output maximum adjustable voltage/V Temperature coefficient "/° Source, after being stabilized by LM2940 low voltage drop integrated regulator, it provides energy for the load. For this purpose, the voltage is selected to be 2.5V, and the reference source is the basic circuit of TL431.

The current resistance is R6=1; the current is (5=2.5mA, which meets the working conditions of the device.

2.2 Calculation of sampling resistance When 8V, it can be seen from formula (2) that the voltage drop of R8 is about 3.2V. Since the internal resistance of IM393 is very high, the higher the resistance of the sampling circuit, the smaller the power consumption. Under the premise of meeting the input requirements of IM393, R8 is 10, and the sampling current is about 320PA, Based on this, we can calculate (R9+V1)7.6k, or use a resistor of 6.8k and a potentiometer of 3k, R9200 (b) The relationship between the reference voltage Vo and the resistors R1 and R2 is based on the calculation results. The protection voltage is checked: 5.85V basically meets the original design requirements.

3 Conclusion In the actual circuit, in order to ensure the precise control of the over-discharge protection of the button battery 2032, Vi is adjusted by a precision potentiometer. For button battery 2032 packs with different voltages, the reference voltage can be adjusted using the circuit (b), and the resistance values of Ri and R2 can be determined according to formula (1).

Since the circuit has added a warning function for insufficient capacity, the staff can prepare in advance to avoid unnecessary losses caused by sudden power outages; when the button battery 2032 reserve energy is close to being discharged when unattended, the load is forcibly powered off to protect the button battery 2032 from damage.

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