760
19.4.3
Input Sampling and A/D Conversion Time
The A/D converter has a built-in sample-and-hold circuit. The A/D converter samples the analog
input at a time t
D
after the ADST bit is set to 1, then starts conversion. Figure 19-5 shows the A/D
conversion timing. Table 19-4 indicates the A/D conversion time.
As indicated in figure 19-5, the A/D conversion time includes t
D
and the input sampling time. The
length of t
D
varies depending on the timing of the write access to ADCSR. The total conversion
time therefore varies within the ranges indicated in table 19-4.
In scan mode, the values given in table 19-4 apply to the first conversion time. The values given
in table 19-5 apply to the second and subsequent conversions. In both cases, set bits CKS1 and
CKS0 in ADCR to give a conversion time of at least 10 µs when AV
CC
≥
4.5 V, and at least 16 µs
when AV
CC
< 4.5 V.
(1)
(2)
t
D
t
SPL
t
CONV
ø
Input sampling
timing
ADF
Address
Write signal
Legend
(1)
: ADCSR write cycle
(2)
: ADCSR address
t
D
: A/D conversion start delay
t
SPL
: Input sampling time
t
CONV
: A/D conversion time
Figure 19-5 A/D Conversion Timing
Содержание H8S/2631
Страница 28: ...xviii Appendix G Package Dimensions 1154 ...
Страница 341: ...316 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 9 8 Memory Mapping in Block Transfer Mode ...
Страница 918: ...905 ø DREQ0 DREQ1 tDRQS tDRQH Figure 25 19 DMAC DREQ Input Timing ...
Страница 955: ...943 A 2 Instruction Codes Table A 2 shows the instruction codes ...