HT46801N-1 Holtek Semiconductor, HT46801N-1 Datasheet - Page 40

• Manufacturer Part Number: HT46801N-1
• Description: (HT4xR01x-1) Small Package 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

www.DataSheet.co.kr
Pulse Width Modulator
The HT46R01B-1 and HT46R01N-1 devices include 1
8-bit PWM outputs. Useful for the applications such as
motor speed control, the PWM function provides out-
puts with a fixed frequency but with a duty cycle that can
be varied by setting particular values into the corre-
sponding PWM register.
PWM Operation
The register, known as PWM and located in the Data
Memory is assigned to each Pulse Width Modulator
channel. It is here that the 8-bit value, which represents
the overall duty cycle of one modulation cycle of the out-
put waveform, should be placed. To increase the PWM
modulation frequency, each modulation cycle is subdi-
vided into two or four individual modulation subsections,
known as the 7+1 mode or 6+2 mode respectively. The
required mode and the on/off control for each PWM
channel is selected using the CTRL0 register. Note that
when using the PWM, it is only necessary to write the re-
quired value into the PWMn register and select the re-
quired mode setup and on/off control using the CTRL0
register, the subdivision of the waveform into its
sub-modulation cycles is implemented automatically
within the microcontroller hardware. The PWM clock
source is the system clock f
the original modulation cycle into a further 2 or 4
sub-cycles enable the generation of higher PWM fre-
quencies which allow a wider range of applications to be
served. The difference between what is known as the
PWM cycle frequency and the PWM modulation fre-
quency should be understood. As the PWM clock is the
system clock, f
the overall PWM cycle frequency is f
when in the 7+1 mode of operation the PWM modulation
frequency will be f
frequency for the 6+2 mode of operation will be f
6+2 PWM Mode
Each full PWM cycle, as it is controlled by an 8-bit PWM
register, has 256 clock periods. However, in the 6+2
PWM mode, each PWM cycle is subdivided into four in-
dividual sub-cycles known as modulation cycle 0 ~ mod-
ulation cycle 3, denoted as i in the table. Each one of
these four sub-cycles contains 64 clock cycles. In this
mode, a modulation frequency increase of four is
achieved. The 8-bit PWM register value, which repre-
sents the overall duty cycle of the PWM waveform, is di-
Rev.1.00
f
f
SYS
SYS
/64 for (6+2) bits mode
/128for (7+1) bits mode
Modulation
PWM
SYS
, and as the PWM value is 8-bits wide,
SYS
/128, while the PWM modulation
SYS
PWM Cycle
Frequency
. This method of dividing
f
SYS
/256
SYS
/256. However,
PWM Cycle
[PWM]/256
Duty
SYS
/64.
40
vided into two groups. The first group which consists of
bit2~bit7 is denoted here as the DC value. The second
group which consists of bit0~bit1 is known as the AC
value. In the 6+2 PWM mode, the duty cycle value of
each of the four modulation sub-cycles is shown in the
following table.
The following diagram illustrates the waveforms associ-
ated with the 6+2 mode of PWM operation. It is impor-
tant 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.
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 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.
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.
Modulation cycle i
Modulation cycle i
Parameter
Parameter
(i=0~3)
(i=0~1)
6+2 Mode Modulation Cycle Values
7+1 Mode Modulation Cycle Values
HT46R01B-1/HT46R01N-1
HT48R01B-1/HT48R01N-1
AC (0~3)
AC (0~1)
i<AC
i AC
i<AC
i AC
(Duty Cycle)
(Duty Cycle)
June 9, 2011
DC+1
DC+1
128
128
DC
DC
DC
DC
64
64
Datasheet pdf - http://www.DataSheet4U.net/