Holtek HT46R003B Manual page 43

HT46R003B
Cost-Effective A/D 8-bit OTP MCU
The following diagram illustrates the waveforms associated with the 6+2 mode of PWM operation.
It is important to note how the single PWM cycle is subdivided into 4 individual modulation cycles,
numbered from 0~3 and how the AC value is related to the PWM value.
f / 2
S Y S
[ P W M ] = 1 0 0
P W M
2 5 / 6 4
[ P W M ] = 1 0 1
P W M
2 6 / 6 4
[ P W M ] = 1 0 2
P W M
2 6 / 6 4
[ P W M ] = 1 0 3
P W M
2 6 / 6 4
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 0
b 7
7+1 PWM Mode
Each full PWM cycle, as it is controlled by an 8-bit PWM register, has 256 clock periods. However,
in the 7+1 PWM mode, each PWM cycle is subdivided into two individual sub-cycles known as
modulation cycle 0 ~ modulation cycle 1, denoted as i in the table. Each one of these two sub-cycles
contains 128 clock cycles. In this mode, a modulation frequency increase of two is achieved. The
8-bit PWM register value, which represents the overall duty cycle of the PWM waveform, is divided
into two groups. The first group which consists of bit 1~bit 7 is denoted here as the DC value. The
second group which consists of bit 0 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.
The following diagram illustrates the waveforms associated with the 7+1 mode PWM operation. It
is important to note how the single PWM cycle is subdivided into 2 individual modulation cycles,
numbered from 0 and 1 and how the AC value is related to the PWM value.
Rev. 1.00
Parameter AC (0~3)
Mod�lation cycle i
(i=0~3)
6+2 Mode Modulation Cycle Values
2 5 / 6 4 2 5 / 6 4
2 5 / 6 4 2 5 / 6 4
2 6 / 6 4 2 5 / 6 4
2 6 / 6 4 2 6 / 6 4
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
P W M c y c l e : 2 5 6 / f
S Y S
6+2 PWM Mode
b 0
PWM Register for 6+2 Mode
Parameter
Mod�lation cycle i
(i=0~1)
�3
DC DC (Duty Cycle)
i<AC (DC+1)/6�
i>AC DC/6�
2 5 / 6 4
2 5 / 6 4
2 5 / 6 4
2 5 / 6 4
M o d u l a t i o n c y c l e 3
P W M R e g i s t e r ( 6 + 2 ) M o d e
A C v a l u e
D C v a l u e
AC(0~1) DC (Duty Cycle)
i<AC (DC+1)/1�8
i>=AC DC/1�8
2 5 / 6 4
2 6 / 6 4
2 6 / 6 4
2 6 / 6 4
M o d u l a t i o n c y c l e 0
��ne 1�� �01�