Digital peak detector with follower mode

摘要

Circuits and processes for detecting a peak value of an input signal are disclosed. In one example, a peak detector circuit may sample a line sense signal, determine the peak value of the line sense signal during a search window, and output a peak detection signal representative of the determined peak value. In a first mode, the peak detector circuit may cause the peak detection signal to be representative of the determined peak value from an immediately preceding search window. In a second mode, the peak detector circuit may cause the peak detection signal to follow the sampled line sense signal. The peak detector circuit may operate in the second mode in response to the sample of the line sense signal being greater than a peak value of the line sense signal from an immediately preceding search window by more than a threshold amount.

主权项

1. A digital peak detection circuit for use in a controller of a power converter, the digital peak detection circuit comprising:
an input to be coupled to receive a digital sample of a line sense signal that is representative of an input voltage of the power converter; a first comparison circuit coupled to compare the digital sample with a present maximum signal representing a maximum value of the line sense signal for a presently occurring search window and, in response to the digital sample exceeding the present maximum signal, update the present maximum signal; a second comparison circuit coupled to compare the present maximum signal with a peak value of the line sense signal from an immediately preceding search window and output an output signal, wherein in response to the present maximum signal being greater than the peak value of the line sense signal from the immediately preceding search window by more than a threshold amount, the second comparison circuit causes the output signal to follow the present maximum signal until an end of the presently occurring search window, and wherein in response to the present maximum signal not being greater than the peak value of the line sense signal from the immediately preceding search window by more than the threshold amount, the second comparison circuit causes the output signal to represent the peak value of the line sense signal from the immediately preceding search window.