Voltage detection and control circuit

Abstract

The invention relates to a voltage detection and control circuit which comprises a switching control unit and a capacitor unit, wherein, the switching control unit is connected between the cathode end of a diode and a voltage detection point, the capacitor unit comprises a first capacitor and a second capacitor, wherein, the first capacitor is connected with the switching control unit, and the second capacitor is connected with the cathode end of the diode. The invention adopts the capacitor unit with the smaller capacitance value, and the DSL user-side device still has sufficient surplus power to send out a power failure signal during the power failure so as to reduce the manufacture cost of the integral circuit.

Description

technical field [0001] The present invention relates to a voltage detection and control circuit. The present invention adopts a capacitor unit with a small capacitance value, so that the DSL user end equipment still has enough remaining power to send a power-off signal when the power is cut off, so as to reduce the overall circuit voltage. Manufacturing costs. Background technique [0002] When using a DSL client device (such as an ADSL modem) for broadband connection, the connection of the DSL client device may be interrupted due to a power outage. [0003] In order to let the ISP network manager know that the DSL connection interruption is caused by the power interruption, the DSL international standard specification ITU G.992.1 stipulates that the DSL user equipment must send a power failure signal (Dying Gasp signal) before the DSL connection is completely interrupted. To the ISP network management terminal, as the basis for the ISP network management personnel to judge...

AI Technical Summary

Problems solved by technology

However, although this can successfully reduce the magnitude of the surge current, the total capacitance of the capacitors 151 / 153 is still approximately equal to that of the capacitor 15, which is not beneficial for cost control.

[0010] Furthermore, at the moment of power failure, the terminal voltage Vd(+) on the voltage detection point 17 can still receive the charge stored in the internal capacitor of the transformer used to generate the external power supply 21 and slowly discharge, and the slow discharge will delay the terminal voltage. The time when the voltage Vd(+) reaches a low potential, so that the DSL user end equipment delays knowing the power-off situation, and during the slow discharge of the terminal voltage Vd(+), the internal capacitor of the DSL user end equipment will also follow Since the DSL client equipment requires a minimum operating voltage to operate normally, if the power-off status is known later, the relative processing time between the DSL user-end equipment being informed of the power-off status and the power-off signal being able to operate (for example : about 14ns) will be compressed accordingly, and may also cause the DSL client equipment to fail to send a power-off signal successfully

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