Datasheet

Section 19 A/D Converter
Rev. 4.00 Jun 06, 2006 page 551 of 1004
REJ09B0301-0400
Section 19 A/D Converter
19.1 Overview
The H8S/2138 Group and H8S/2134 Group incorporate a 10-bit successive-approximations A/D
converter that allows up to eight analog input channels to be selected.
In addition to the eight analog input channels, up to 8 channels of digital input can be selected for
A/D conversion. Since the conversion precision falls to the equivalent of 6-bit resolution when
digital input is selected, digital input is ideal for use by a comparator identifying multi-valued
inputs, for example.
19.1.1 Features
A/D converter features are listed below.
• 10-bit resolution
• Eight (analog) or 8 (digital) input channels
• Settable analog conversion voltage range
 The analog conversion voltage range is set using the analog power supply voltage pin
(AVcc) as the analog reference voltage
• High-speed conversion
 Minimum conversion time: 6.7 µs per channel (at 20-MHz operation)
• Choice of single mode or scan mode
 Single mode: Single-channel A/D conversion
 Scan mode: Continuous A/D conversion on 1 to 4 channels
• Four data registers
 Conversion results are held in a 16-bit data register for each channel
• Sample and hold function
• Three kinds of conversion start
 Choice of software or timer conversion start trigger (8-bit timer), or ADTRG pin
• A/D conversion end interrupt generation
 An A/D conversion end interrupt (ADI) request can be generated at the end of A/D
conversion