p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 484

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 17 A/D Converter
17.4.3
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
) passes after the ADST bit in ADCSR is set to
D
1, then starts A/D conversion. Figure 17.2 shows the A/D conversion timing. Table 17.3 indicates
the A/D conversion time.
As indicated in figure 17.2, the A/D conversion time (t
) includes t
and the input sampling time
CONV
D
(t
). The length of t
varies depending on the timing of write to ADCSR. The total conversion
SPL
D
time therefore varies within the ranges indicated in table 17.3.
In scan mode, the values shown in table 17.3 become those for the first conversion time. For the
second and subsequent conversions, the conversion time is 266 states (fixed) when CKS = 0 and
134 states (fixed) when CKS = 1. Use the conversion time of 134 states only when the system
clock (φ) is 16 MHz or lower.
Rev. 1.00 Sep. 21, 2006 Page 446 of 658
REJ09B0310-0100