Datasheet
Section 18 I
2
C Bus Interface [Option]
(This function is not available in the H8S/2695)
Page 892 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
TM
,
H8S/2633R F-ZTAT
TM
, H8S/2695
Table 18.7 Permissible SCL Rise Time (t
Sr
) Values
Time Indication
IICX
t
cyc
Indication
I
2
C Bus
Specification
(Max.)
φ =
5 MHz
φ =
8 MHz
φ =
10 MHz
φ =
16 MHz
φ =
20 MHz
φ =
25 MHz
φ =
28 MHz
0 7.5 t
cyc
Standard
mode
1000 ns 1000 ns 937 ns 750 ns 468 ns 375 ns — —
High-speed
mode
300 ns 300 ns 300 ns 300 ns 300 ns 300 ns — —
1 17.5 t
cyc
Standard
mode
1000 ns 1000 ns 1000 ns 1000 ns 1000 ns 875 ns 700 ns 624 ns
High-speed
mode
300 ns 300 ns 300 ns 300 ns 300 ns 300 ns 300 ns 300 ns
Note: When 7.5 t
cyc
is selected as the transfer rate, the actual transfer rate may be extended if φ
exceeds 20 MHz.
• The I
2
C bus interface specifications for the SCL and SDA rise and fall times are under 1000 ns
and 300 ns. The I
2
C bus interface SCL and SDA output timing is prescribed by t
Scyc
and t
cyc
, as
shown in table 18.6. However, because of the rise and fall times, the I
2
C bus interface
specifications may not be satisfied at the maximum transfer rate. Table 18.8 shows output
timing calculations for different operating frequencies, including the worst-case influence of
rise and fall times.
t
BUFO
fails to meet the I
2
C bus interface specifications at any frequency. The solution is either
(a) to provide coding to secure the necessary interval (approximately 1 µs) between issuance of
a stop condition and issuance of a start condition, or (b) to select devices whose input timing
permits this output timing for use as slave devices connected to the I
2
C bus.
t
SCLLO
in high-speed mode and t
STASO
in standard mode fail to satisfy the I
2
C bus interface
specifications for worst-case calculations of t
Sr
/t
Sf
. Possible solutions that should be
investigated include (a) adjusting the rise and fall times by means of a pull-up resistor and
capacitive load, (b) reducing the transfer rate to meet the specifications, or (c) selecting
devices whose input timing permits this output timing for use as slave devices connected to the
I
2
C bus.