HT46F49E datasheet(36/88 Pages) HOLTEK

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HT46F46E/HT46F47E/HT46F48E/HT46F49E

Rev. 1.40

July 28, 2009

7+1 PWM Mode

Each full PWM cycle, as it is controlled by an 8-bit PWM,

PWM0 or PWM1 register, has 256 clock periods. How-

ever, in the 7+1 PWM mode, each PWM cycle is subdi-

vided into two individual sub-cycles known as modulation

cycle 0 ~ modulation cycle 1, denoted as

²i² in the table.

Each one of these two sub-cycles contains 128 clock cy-

cles. In this mode, a modulation frequency increase of

two is achieved. The 8-bit PWM, PWM0 or PWM1 regis-

ter value, which represents the overall duty cycle of the

PWM waveform, is divided into two groups. The first

group which consists of bit1~bit7 is denoted here as the

DC value. The second group which consists of bit0 is

known as the AC value. In the 7+1 PWM mode, the duty

cycle value of each of the two modulation sub-cycles is

shown in the following table.

Parameter

AC (0~1)

(Duty Cycle)

Modulation cycle i

(i=0~1)

<AC

DC+1

128

³AC

128

7+1 Mode Modulation Cycle Values

The following diagram illustrates the waveforms associ-

ated with the 7+1 mode of PWM operation. It is impor-

tant to note how the single PWM cycle is subdivided into

2 individual modulation cycles, numbered 0 and 1 and

how the AC value is related to the PWM value.

f S Y S / 2

P W M

[ P W M ] = 1 0 0

[ P W M ] = 1 0 1

P W M

[ P W M ] = 1 0 2

P W M

[ P W M ] = 1 0 3

P W M

P W M c y c l e : 2 5 6 / f S Y S

2 5 / 6 4

2 6 / 6 4

2 5 / 6 4

2 6 / 6 4

2 5 / 6 4

2 6 / 6 4

2 5 / 6 4

2 6 / 6 4

M o d u l a t i o n c y c l e 0

P W M m o d u l a t i o n p e r i o d : 6 4 / f S Y S

M o d u l a t i o n c y c l e 1

M o d u l a t i o n c y c l e 2

M o d u l a t i o n c y c l e 3

M o d u l a t i o n c y c l e 0

6+2 PWM Mode

f S Y S / 2

P W M

[ P W M ] = 1 0 0

[ P W M ] = 1 0 1

P W M

[ P W M ] = 1 0 2

P W M

[ P W M ] = 1 0 3

P W M

P W M m o d u l a t i o n p e r i o d : 1 2 8 / f S Y S

5 0 / 1 2 8

5 1 / 1 2 8

5 2 / 1 2 8

5 0 / 1 2 8

5 1 / 1 2 8

5 0 / 1 2 8

5 1 / 1 2 8

5 2 / 1 2 8

M o d u l a t i o n c y c l e 0

P W M c y c l e : 2 5 6 / f S Y S

M o d u l a t i o n c y c l e 1

M o d u l a t i o n c y c l e 0

7+1 PWM Mode

P W M , P W M 0 , P W M 1 R e g i s t e r s

( 6 + 2 ) M o d e

b 7

b 0

A C v a l u e

D C v a l u e

6+2 Mode Pulse Width Modulation Register

HT46F49E Datasheet(PDF) 36 Page - Holtek Semiconductor Inc

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