Low-Temperature Drift Oscillator Design for Multi-Cell Lithium Battery Packs

In the battery management chip, in order to save power consumption, an RC relaxation oscillator is used. In view of the large temperature coefficient and high power consumption of traditional RC oscillators, this paper designs a low-temperature drift relaxation oscillator for multi-cell lithium battery packs. The oscillator consists of a start-up module, an RC charge and discharge module, and a reference source module. The zero temperature coefficient current is used to charge and discharge the capacitor, and the critical voltages V Hand V L that can be reached by charging and discharging the capacitor are clamped by controlling the on-off of the MOSFET in parallel with the resistor, instead of using a traditional voltage comparator to compare the capacitor voltage with the reference voltage, thus greatly simplifying the circuit structure and reducing the temperature coefficient and power consumption of the circuit. At the tt process angle of 3.3V power supply voltage and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$27^{\circ} \mathrm{C}$</tex>, the oscillation frequency of the output signal is 32.85kHz, the average power consumption of the circuit is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10.94_{\mu}\mathrm{W}$</tex>, and the frequency temperature coefficient at this process angle is 58.45 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{ppm}/^{\circ}\mathrm{C}$</tex>.