Current monitoring circuit for lithium battery

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Overview:
A current monitoring circuit for lithium batteries is proposed. The current is sampled by introducing a sensitive resistor in the power supply loop of the Lithium Battery, and the switch-capacitor operational amplifier and high-speed comparator are used to convert the analog signal to the digital signal. . The precise current amount calculation in the processor can protect the overcurrent and short circuit currents, and can also be used to accurately calculate the relevant parameters such as battery impedance and power. The circuit is based on a 0.18 m CMOS process with a supply voltage of 2.5 V. The designed circuit was verified by simulation. The results show that the circuit can realize the sampling and encoding function of current in the range of application temperature range of -40 °C to +125 °C, and can judge the charging and discharging action.
As a new clean and renewable secondary energy source, lithium batteries need to accurately monitor their current, voltage and temperature parameters, and make appropriate protection circuits. For handheld devices, it is more necessary to pursue high precision and low power consumption, thereby reducing the "excessive" use of lithium batteries and prolonging the service life.
The circuit designed in this paper introduces a sensitive resistor in the lithium battery power supply loop to monitor the current, provide charging and discharging tips for the system, and can be used for power calculation and protection control.
This paper will elaborate on the principle of the current monitoring system and the internal circuit structure, and give the H-spice simulation results and related conclusions.

1 The current monitoring circuit analog-to-digital converter (ADC) designed in this paper consists of sampling, quantization and coding. The block diagram of the lithium battery current monitoring system designed in this paper is shown in Figure 1. Among them, the capacitor and the AMP amplifier form a switching capacitor sampling circuit, the C0MP high-speed comparator quantizes the data, and the processor performs digital logic control and encoding on the circuit. The bias circuit provides an AMP amplifier self-starting branch and generates Vbe1 and Vbe4. The clock module controls system switches, including LII, LI2, LI5, LI6, and LI38. The processor outputs a digital signal Logic Control that changes the quantization capacitance.

Figure 1 Lithium battery current monitoring system block diagram (please read the PDF for details)