2.4 Multi-Function Timer
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Chapter 2: Hardware
2.4 Multi-Function Timer
2.4.1 Overview
The multi-function timer controls up to 7 real-time output pins, and incorporates the following functions.
Interval Timer Function
Produces pulse output or interrupt signal at fixed time intervals.
PWM Output Function
Produces a fixed-period pulse with duty factor (ratio of ‘L’ output width to ‘H’ output width) varied
in real-time.
Three-Phase AC Sine Wave Approximation Output (Interval Control Output) Function
Produces an approximation of 3-phase AC sine wave output (with variable setting for non-
overlapping intervals) as used in AC motor interval controls.
The multi-function timer also provides the following features:
14-bit Timer for Pulse Period Control
A prescaler provides a clock source signal selection of 1/2/8/16 machine cycles (minimum
resolution: 62.5 ns at 16 MHz operation).
For AC motor control applications, carrier frequencies up to 30 kHz are available in 8-bit steps.
The selection of count modes includes up-count only or up/down count mode.
A buffer is provided, which can be used with the zero-detection feature to transfer from the buffer
enabling period length adjustment in real-time.
Compare Register for Duty Factor Control
The MB90660A has four compare registers enabling independent output pulse duty on individual
four channels.
Each channel has a buffer, which can be used with the zero-detection feature to trigger buffer output
enabling period length adjustment in real-time.
Dead-time Timer for Non-Overlapping Control
The dead-time timer provides the ability to generate 3-channel PWM output in addition to non-
overlapping inverted signals. This enables generation of AC motor control waveforms (U, V, W, X,
Y, Z).
A prescaler provides, as dead-time timer clock source, signal selection of 1/2/8/16 machine cycles
(minimum resolution: 62.5 ns at 16 MHz).
DTTI Pin Input for Forced Stop Control
The DTTI pin input signal can be used together with software to forcibly fix pin output levels.
This input signal can be used for inactive period control in AC motor control applications.
The use of a clockless DTTI pin input signal enables pin control from external sources even when
the MB90660A oscillator is stopped.
Flag Set for Event Detection and Interrupt Generation
The 14-bit timer has a flag set used for zero detection and interrupt generation in case of overflow,
compare clear register matching, TRG pin input signal clearing or matching with any of the 4-
channel compare registers (interrupt output disable settings also available).