M66244FP Просмотр технического описания (PDF) - MITSUBISHI ELECTRIC

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M66244FP

High Speed Monolithic Pulse Width Modulator

MITSUBISHI ELECTRIC  

June 1998 Ver.8.0.0

MITSUBISHI <DIGITAL ASSP>

M66244FP

High Speed Monolithic Pulse Width Modulator

FUNCTION

M66244 can control "H" width and positioning of PWM output by DATA pins (D<5:0> ) and

CONTROL pins (SEM/DEM,LEM/TEM) in each CLK period.

These inputs can be updated on the rising edge of the CLK.

Positioning the width-controlled pulse are begging , middle ,or end of the clock period.

This is accomplished through CONTROL pins (SEM/DEM,LEM/TEM)

Pulse positioning within the clock period is defined by the following CONTROL truth table.

SEM/DEM

1

1

0

LEM/TEM

1

0

X

Alignment

Right hand justify

Left hand justify

Center justify

SEM/DEM : single edge modulation / dual edge modulation

LEM/TEM : leading edge modulation / trailing edge modulation

The diagram of page4 illustrates the output of the M66244FP with various DATA(D<5:0>) ,

CONTROL(SEM/DEM, LEM/TEM) inputs and PWM output.

This does not take into account any delays,which will explain later.

The rising edge is delayed from the leading edge of the clock, and the falling edge is delayed

from the center of the clock period.

Top line shows the clock; the second shows DATA inputs ; third shows CONTROL inputs

being updated on the rising edge of clock. The forth line shows the resulting PWM pulse with an

explanation of the second and third lines.

In the first cycle (Ncycle) , DATA is 3F . So the CONTROL value is shown as "X". This

means the value is not important because a 100% pulse will be output for any CONTROL value.

In the second cycle (N+1cycle) , DATA is 1F , SEM/DEM is "H" and LEM/TEM is "H". This

means PWMoutput width is 50% and positioning is right hand justify.

In the third cycle (N+2cycle) , DATA is 0F , SEM/DEM is "L" and LEM/TEM is "X". This means

PWMoutput width is 25% and positioning is center justify.

In the fourth cycle (N+3cycle) , DATA is 2F , SEM/DEM is "H" and LEM/TEM is "L". This

means PWMoutput width is 75% and positioning is left hand justify.

In the fifth cycle (N+4cycle) , DATA is 00 . So the CONTROL value is shown "X" . This means

the value is not important because a 0% pulse will be output for any CONTROL value.

C 1998 MITSUBISHI ELECTRIC CORPORATION

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