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11
A/D CONVERTER
11-3
32185/32186 Group Hardware Manual
Rev.1.10 REJ09B0235-0110 May 15, 07
11.1 Outline of A/D Converter
(7) Inflow Current Bypass Circuit
If an overvoltage or negative voltage is applied to any analog input channel which is currently inactive, a
current flows into or out of the analog input channel currently being A/D converted via the internal circuit,
causing the conversion accuracy to degrade. To solve this problem, the A/D Converter incorporates a
circuit that bypasses such inflow current. This circuit is always enabled.
(8) Conversion Speed
The A/D conversion speed is shown in Table 11.1.1 below. The A/D conversion speed is decided by select-
ing combination such as with or without Sample-and-Hold and selecting Normal or Fast Sample-and-Hold,
selecting Slow or Fast mode, selecting Normal or Double speed. Conversion speed of comparator mode is
decided by selecting combination such as selecting Slow or Fast mode, selecting Normal or Double speed.
(9) Interrupt Request and DMA Transfer Request Generation Functions
An A/D conversion interrupt or DMA transfer request can be generated each time A/D conversion (single mode
operation, single-shot scan operation or one cycle of continuous operation) or comparate operation is completed.
Note 1: To discriminate between the comparison performed internally by the successive
approximation-type A/D Converter and that performed in comparator mode using the same
A/D Converter as a comparator, the comparison in comparator mode is referred to in this
manual as “comparate.”
Table 11.1.1 outlines the A/D Converter and Figure 11.1.1 shows block diagram of A/D Converter.
Table 11.1.1 Outline of the A/D Converter (1/2)
Item
Description
Analog input
16 channels x 1
A/D conversion method
Successive approximation method
Resolution
10 bits (Conversion result can be read out in either 8 or 10 bits)
Absolute accuracy
Sample-and-hold is disabled
Slow mode
Normal speed
± 2LSB
(Note 1)
Double speed
± 2LSB
(Note 2)
Fast mode
Normal speed
± 3LSB
Double speed
± 3LSB
Normal Sample-and-hold is enabled,
Slow mode
Normal speed
± 2LSB
Simultaneous sampling is disabled
Double speed
± 2LSB
Fast mode
Normal speed
± 3LSB
Double speed
± 3LSB
Fast Sample-and-hold is enabled,
Slow mode
Normal speed
± 3LSB
Simultaneous sampling is disabled
Double speed
± 3LSB
Fast mode
Normal speed
± 3LSB
Double speed
± 8LSB
Normal Sample-and-hold is enabled,
Slow mode
Normal speed
± 3LSB
Simultaneous sampling is enabled
Double speed
± 3LSB
Fast mode
Normal speed
± 3LSB
Double speed
± 3LSB
Fast Sample-and-hold is enabled,
Slow mode
Normal speed
± 3LSB
Simultaneous sampling is enabled
Double speed
± 3LSB
Fast mode
Normal speed
± 3LSB
Double speed
± 8LSB