NT68P62-01 Datasheet, PDF (15/56 Pages) List of Unclassifed Manufacturers – 8-Bit Microcontroller for Monitor (32K OTP ROM Type)

NT68P62-01
9. PWM DACs (Pulse Width Modulation D/A Converters)
There are 13 PWM D/A converters with 8-bit resolution in NT68P62. All of these D/A (DAC0 - DAC12) converters are open-
drain output structure with external 5V applied maximum. DAC0 – DAC6 are dedicated PWM channels, and DAC7 - DAC12
are shared with I/O pins. Those shared PWM channels are activated by clearing the correspondent control bits in the
ENDAC control register ($000F). When users write '0' into one of the enable control bits, its correspondent I/O pin will be
switched to PWM output pin.
The PWM refresh rate is 62.5KHz operating on 8MHz system clock. There are 13 readable DACH registers corresponding to
13 PWM channels ($0030 - $003D). Each PWM output pulse width is programmable by setting the 8 bit digital to the
corresponding DACH registers. When these DACH registers are set to 00H, the DAC will output LOW (GND level) and every
1 bit addition will add 62.5ns pulse width. After reset, all DAC outputs are set to 80H (1/2 duty output). (Please refer to Figure
9.1 for the detailed timing diagram of PWM D/A output.)
8MHz Fosc
PWM value : 255 0
1
2
3
00
01
02
03
m-1
m
255 ⁰
1
m
255(FF)
Figure 9.1. The DAC Output Timing Diagram and Wave Table
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