Hello,
Today, I would like to share with you this topic which Introduces the ADSL's Dying gasp effect.
Dying gasp signal refers to:
When the system input voltage cannot meet the normal operation of the system. The system will automatically send a signal to the headend. Tell the headend that the CPE end may not work properly. The headend reacts accordingly. Release the channel originally assigned to the CPE.
The principle of system Dying gasp:
Chip manufacturers will design a Dying gasp performance module in the chip when designing the chip. This module implements the Dying gasp function by monitoring the external input voltage. Because the prerequisite for this function to work properly is that the chip must still be able to work normally, and a certain length of time must be sent to the head end, so within the effective time of the Dying gasp signal defined by the forum, various power supplies for the chip to work The voltage should not be less than the minimum operating voltage described in this chip specification. In other words, the difference between the starting voltage of the monitoring point and the working voltage of the chip cannot be less than the legal Dying gasp signal time length.
Dying Gasp, as the name suggests-"breath before death", using the last bit of stored electricity allows the CPE to send out the final status information.
There are two parts of the circuit:
1- Large capacitor energy storage. When the external input power supply is powered off, the electrical energy stored in the large capacitor releases the energy for the entire core circuit to work. The breathing time, generally a few ms. The circuit is a very simple-diode large capacitance (electrolytic, the capacity depends on the power consumption of the circuit board and the voltage range that can be normally rectified) voltage comparator.
2- The main chip of ADSL has an input pin to detect the output level of the voltage comparator. Once triggered, it can send an interrupt signal to let the system enter the "willingness" state.
Welcome to leave a message and exchange in the comment area.
Thanks!
