UPD784938 Datasheet, PDF (399/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 15 PWM OUTPUT UNIT
15.3 PWM Output Unit Operation
15.3.1 Basic PWM output operation
The PWM pulse output duty is determined by the value set in bits 4 to 15 of the PWM modulo register (PWMn: n = 0,
1) as shown below.
(Value of PWMn bits 4 to 15)^Note + 1
PWM pulse output duty =
4,096
Note 16 ≤ (Value of PWMn bits 4 to 15) ≤ 4095
The PWM pulse output repetition frequency is the frequency obtained by division-by-256 of the PWM clock fCLK/1 to
fCLK/4 set by the PWM prescaler register (PWPR) (=fPWMC/256), and the minimum pulse width is 1/fPWMC.
In PWM pulse output, 12-bit resolution is achieved by repeating output of a fPWMC/256 repetition frequency 8-bit resolution
PWM signal 16 times.
The addition of extra pulses (1/fPWMC) to the 8-bit resolution PWM pulses determined by bits 8 to 15 of the PWMn every
cycle is controlled in accordance with the value of bits 4 to 7 of the PWMn to implement a PWM pulse signal once every
16 cycles.
Figure 15-4. Basic PWM Output Operation
PWM signal
Note
One 12-bit PWM signal cycle
Note 8-bit resolution per PWM pulse cycle
Preliminary User’s Manual U13987EJ1V0UM00
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