HT46R01/HT46R02/HT46R03
b
7
b
0
P
W
M
R
e
g
i
s
t
e
r
(
6
+
2
)
M
o
d
e
A
D
C
v
a
l
u
u
e
C
v
a
l
e
PWM Register for 6+2 Mode
7+1 PWM Mode
DC
Parameter
AC (0~1)
i<AC
(Duty Cycle)
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 indi-
vidual sub-cycles known as modulation cycle 0 ~ modula-
tion 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 bit1~bit7 is de-
noted 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 mod-
ulation sub-cycles is shown in the following table.
DC+1
128
Modulation cycle i
(i=0~1)
DC
i³AC
128
7+1 Mode Modulation Cycle Values
The following diagram illustrates the waveforms associ-
ated with the 7+1 mode PWM operation. It is important
to note how the single PWM cycle is subdivided into 2 in-
dividual modulation cycles, numbered 0 and 1 and how
the AC value is related to the PWM value.
S
Y
S
[
P
W
M
]
=
1
0
0
P
W
M
5
5
5
0
1
1
/
/
/
1
1
1
2
2
2
8
8
8
5
0
/
1
2
8
5
0
/
1
2
8
[
P
W
M
]
=
1
0
1
P
W
M
5
0
/
1
2
8
5
1
/
1
2
8
[
P
W
M
]
=
1
0
2
P
W
M
5
1
/
1
2
8
5
1
/
1
2
8
[
P
W
M
]
=
1
0
3
P
W
M
5
1
/
1
2
8
5
2
/
1
2
8
5
2
/
1
2
8
P
W
M
m
o
d
u
l
a
t
i
o
n
p
e
r
i
o
d
:
1
2
8
/
f
M
o
d
u
l
a
t
i
o
n
c
y
c
l
e
0
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
P
W
M
c
y
c
l
e
:
2
5
6
/
f
7+1 PWM Mode
b
7
b
0
P
W
M
R
e
g
i
s
t
e
r
(
7
+
1
)
M
o
d
e
A
D
C
v
a
l
u
u
e
C
v
a
l
e
PWM Register for 7+1 Mode
Rev. 1.00
25
September 21, 2007
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
