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A/D and D/A Converters
4. A/D and D/A Converters (H8/3927 Series)
Features
Hitachi, Ltd. provides the H8/3927 Series, which includes built-in 8-bit A/D and D/A
converters, as microcomputers for use in analog signal interface applications. The H8/3927
Series microcomputers include 32 kbytes to 60 kbytes of ROM and 1 kbyte of RAM on chip.
Since the D/A converter can directly output analog signals, analog output signals can be
directly controlled without the use of the external PWM generator and low pass filter
components that were previously required to form the D/A converter. Furthermore, eight A/D
converter channels are built in.
These microcomputers provide on-chip ten types of timer (including a watchdog timer), real-
time output ports, a 14-bit PWM, and two serial communication interface channels as
additional peripheral functions.
Furthermore, these microcomputers support low voltage operation (2.7 V) and a rich set of low
power modes including microcomputer operation from a 32 kHz subclock making these
products optimal for applications which require backup operation during power outages or
battery operation.
Built-in multi-channel A/D and
D/A converters
Real time output ports
Low power operation
Low voltage operation
(2.7 V to 5.5 V operation)
•
Direct output of analog voltages
•
D/A converter and PWM differences
Conversion speed
Voltage stability
Circuit structure
D/A
• Port output synchronized with an external signal
with no software overhead
•
Backup operation during power outage
•
Can be used with battery driven equipment that
does not use LCD.
25
Application Perspectives
D/A
PWM
Up to 10 µs
50 µs and over
Low (large ripple
High
current component)
IC
PWM
LPF
IC: Voltage control circuit
IC
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