What is the recovery time and removal time?
In the synchronization circuit, the input data required to meet the setup time and clock hold time can perform normal data transmission, to prevent metastability. Similarly, for an asynchronous reset register, the same asynchronous reset signal and a clock need to meet the same recovery time and removal time to effectively reset operation and the reset operation is released, preventing the metastable output.
1, recovery time: Recovery time
Revoking reset back to the non-reset state level must be a period of time before the clock edge coming soon, in order to ensure that the clock can be effectively recovered to non-reset state, this period is recovery time. Similar to the setup time synchronization clock.
As shown, rst_n 0 denotes a reset, clk rising edge triggered, rst_n from a rising edge to a rising edge of clock 0 1 must not be less than the recovery time to restore the register in order to ensure normal state.
2, removal time: remove time
Reset, after the active clock edge arrival of the reset signal reset also need to keep the time of removal time removal time (removal time). Similar synchronous clock hold time.
As shown, the effective RST_N 0 denotes a reset, clk is rising edge triggered, RST_N remains 0 after the rising edge of clk remains a need for a time effective to ensure the register is reset to prevent metastability.
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Author: IC small pigeon
Source: CSDN
Original: https: //blog.csdn.net/icxiaoge/article/details/80957170
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