| With the types of digital products continuously enriched, its requirements to power management chips are no longer limited to 10V or 20V, but may be 30V, 40V or even higher. However, it has been very difficult for traditional step-up DC/DC switching power supply structures to produce such a high output voltage with common 2.7V to 5V portable batteries.Cascading batteries to increase the input voltage will no doubt increase the size and weight of the power supply, and is not conducive to portability requirements.A new three-stage power supplly converter, which could serve for electronic readers, is designed in this paper. It combines PWM current control type Buck-Boost converter,charge pump and linear regulator. Based on 2.7V to 5V portable power supply, it will produce a stable output voltage higher than -30 volts, with little expense of the efficiency. To reduce the size of the peripheral devices, all power conductors and feedback resistors are integrated in chip. All peripheral components are only five capacitors and one inductor. Over current protection(OCP), over temperature protection(OTP) and under voltage lockout protection(UVLO) circuits have been properly designed to ensure the safe operation of the system.This chip is based on 0.35um BCD6S process. Simulated by eldoD, embedded in Cadence, the results show good performance, and the initial goals are achieved. |
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