6+2 Pwm Mode - Holtek HT45F23A Manual

HT45F23A/HT45F24A
TinyPower Flash MCU with OPA & Comparators
TM

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 individual sub-cycles known as
modulation cycle 0 ~ modulation 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 represents the overall duty cycle of the PWM waveform, is divided 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 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
Rev. 1.40
Parameter AC (0~3)
Modulation 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
75
DC (Duty Cycle)
DC+1
i<AC
64
DC
i≥AC
64
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
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
March 29, 2019