HD6433694 Datasheet, PDF (286/432 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

16.4.3 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 when the A/D conversion start delay time (t_D) has passed after the ADST bit is set to 1, then
starts conversion. Figure 16.2 shows the A/D conversion timing. Table 16.3 shows the A/D
conversion time.
As indicated in figure 16.2, 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 16.3.
In scan mode, the values given in table 16.3 apply to the first conversion time. In the second and
subsequent conversions, the conversion time is 128 states (fixed) when CKS = 0 and 66 states
(fixed) when CKS = 1.
(1)
ø
Address
(2)
Write signal
Input sampling
timing
ADF
t_D
t_SPL
t_CONV
Legend
(1) : ADCSR write cycle
(2) : ADCSR address
t_D : A/D conversion start delay time
t_SPL : Input sampling time
t_CONV : A/D conversion time
Figure 16.2 A/D Conversion Timing
Rev. 4.00, 03/04, page 258 of 400