Datasheet

Section 10 14-Bit PWM D/A
Rev. 4.00 Jun 06, 2006 page 253 of 1004
REJ09B0301-0400
Section 10 14-Bit PWM D/A
10.1 Overview
The H8S/2138 Group and H8S/2134 Group have an on-chip 14-bit pulse-width modulator (PWM)
with two output channels.
Each channel can be connected to an external low-pass filter to operate as a 14-bit D/A converter.
Both channels share the same counter (DACNT) and control register (DACR).
10.1.1 Features
The features of the 14-bit PWM D/A are listed below.
• The pulse is subdivided into multiple base cycles to reduce ripple.
• Two resolution settings and two base cycle settings are available
The resolution can be set equal to one or two system clock cycles. The base cycle can be set
equal to T × 64 or T × 256, where T is the resolution.
• Four operating rates
The two resolution settings and two base cycle settings combine to give a selection of four
operating rates.