Research And Design Of Key Technologies Of A 5 A Driving Current Low Voltage LDO Chip

In recent years,with the rapid development of portable electronic devices,the performance requirements for power management chips have continued to increase.Among them,the low-voltage linear regulator(LDO)has many significant advantages,such as low noise,high power supply rejection ratio,simple peripheral circuit structure,and stable output compared with other types of power chips,and has been widely used.However,the diversity and variability of the application market demand puts forward higher requirements on the performance indicators of LDOs.Among them,LDOs with fast transient response and capable of driving large current loads have become the research focus and hotspot.This thesis designs and implements a 300 mV low dropout LDO linear regulator with a load current of 5 A based on the SMIC 0.13 μm CMOS process.It can convert a 5.5 V power supply voltage into a 2.5 V stable output voltage and has fast transient response characteristics.The linear regulator uses an on-chip integrated high-precision low-temperature drift bandgap reference circuit to generate a reference voltage,and adds a start-up circuit to ensure the normal operation of the bandgap reference.The design and optimization method of the bandgap loop based on pole-zero analysis and compensation further improves the robustness of the reference voltage and shortens the settling time.The load enhancement technology is used in the error amplifier design to achieve the improvement of the LDO power supply rejection ratio,and the error amplifier is phase compensated by the loop compensation method of inserting a buffer stage and a dynamic zero point.The comprehensive design of the over-temperature protection circuit and the under-voltage lockout circuit has realized the multi-dimensional improvement of chip reliability and can effectively improve the service life of the chip.The design and simulation results based on Cadence show that the LDO linear regulator can drive a maximum load current of 5 A,output a voltage of 2.5 V,and a dropout voltage as low as 300 mV.It also has fast transient response characteristics.When there is no-full load jump(1 A/μs),the undershoot voltage is less than 23 mV,the overshoot voltage is less than 24 mV,and the response time is 12 μs.Typically,the linear adjustment rate is 0.123 %,and the load adjustment rate is 0.019 %.At low frequencies,the power supply rejection ratio is 89 dB,and when the frequency is 10 KHz,the power supply rejection ratio reaches 59 dB.When the output voltage is 2.5 V and the load is 5 A,the output noise value is 126.5 μVrms.The over-temperature protection circuit can ensure that the system works normally in a temperature environment below 135 ℃.When the temperature exceeds 135 ℃,the over-temperature protection module starts and the circuit stops working.When the temperature drops to 120 ℃,the circuit resumes operation,with a temperature of 15 ℃.Hysteresis temperature.The undervoltage lockout circuit can ensure that the LDO system works normally when the power supply voltage reaches 2.8 V.When the power supply voltage drops to 2.6 V,the circuit is in an undervoltage lockout state with a hysteresis voltage of 200 mV.