Rev. 1.0, 02/00, page 503 of 1141
23.3.8
Noise Canceler
The logic levels at the SCL and SDA pins are routed through noise cancelers before being latched
internally. Figure 23.13 shows a block diagram of the noise canceler circuit.
The noise canceler consists of two cascaded latches and a match detector. The SCL (or SDA)
input signal is sampled on the system clock, but is not passed forward to the next circuit unless the
outputs of both latches agree. If they do not agree, the previous value is held.
SCL or SDA
input signal
Internal SCL
or SDA signal
Sampling clock
Sampling
clock
System clock
period
C
Latch
Q
D
C
Latch
Q
D
Match
detector
Figure 23.13 Block Diagram of Noise Canceler
23.3.9
Sample Flowcharts
Figures 23.14 to 23.17 show sample flowcharts for using the I
2
C bus interface in each mode.