Power switch circuit suitable for power supply abrupt change, chip and power supply system

Abstract

The invention discloses a power switch circuit suitable for power supply abrupt change, a chip and a power supply system. The circuit comprises a first power switch circuit which switches an output voltage to a standby power supply Vbat when it is monitored that a normal power supply VDD is switched to failure, and switches the output voltage to the VDD after a preset delay time when it is monitored that the VDD is switched to be effective; a mirror image current source which generates a reference current by using the voltage output by the first power switch circuit; a second power switch circuit which is used for switching the output voltage to Vbat when monitoring that the VDD is switched to failure, switching the output voltage to the VDD when monitoring that the VDD is switched to be effective, and mirroring the reference current to charge and discharge the energy storage circuit so as to enable the voltage of the energy storage circuit to reach the output voltage of the second power switch circuit; and a driving circuit which is powered by the first power switch circuit, follows the voltage of the energy storage circuit and outputs the voltage as an RTC power supply. Accordingto the invention, abrupt change during power supply switching can be avoided, and the switched power supply has relatively high driving capability.

Description

Technical field [0001] The invention relates to the field of power supply switching, in particular to a power switch circuit, a chip and a power supply system suitable for a sudden change in power supply. Background technique [0002] In many chip power management systems, such as MCU or ARM, there are often two power systems, and there are even more in some specific chips. Take the two common power supply systems VDD and Vbat as examples below. VDD refers to the normal power supply system of the chip, and Vbat refers to the backup power system, which is generally a battery. Such as figure 1 As shown, 1 represents functional modules powered by VDD, these modules cannot function after VDD power failure, and 2 represents functional modules that still need to work after VDD power failure. The power domain of these modules is VDD_RTC. This dual power system The main design method is that when VDD is turned off, or when VDD is suddenly powered off in an unexpected situation, some spe...

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Problems solved by technology

In addition, in order to reduce the impact of the direct switching of the switch, the control signal of the power switch is often opened in stages, such as Figure 5 As shown, it uses the inverter to charge the capacitor, so that the opening time of each stage switch is different, resulting in a stepwise switching of the power supply. Step ladder switching, the switching schematic diagram is as follows Image 6 As shown, the amount of power variation for each switching is reduced, but it is difficult to achieve a smooth transition during switching, and the overall switching time is also short, which often only achieves certain benefits and cannot fundamentally solve the problem

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