Datasheet

Section 18 I
2
C Bus Interface 2 (IIC2)
Rev. 1.50 Sep. 18, 2007 Page 435 of 584
REJ09B0240-0150
18.4.7 Noise Canceller
The logic levels at the SCL and SDA pins are routed through noise cancellers before being latched
internally. Figure 18.16 shows a block diagram of the noise canceller circuit.
The noise canceller 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.
C
QD
March detector
Internal
SCL or SDA
signal
SCL or SDA
input signal
Sampling
clock
Sampling clock
System clock
period
Latch
Latch
C
Q
D
Figure 18.16 Block Diagram of Noise Canceller
18.4.8 Example of Use
Flowcharts in respective modes that use the I
2
C bus interface are shown in figures 18.17 to 18.20.