NT68F62 Datasheet, PDF (15/57 Pages) List of Unclassifed Manufacturers – 8-Bit Microcontroller for Monitor (32K Flash MTP Type)

NT68F62
9. PWM DACs (Pulse Width Modulation D/A Converters)
There are 13 PWM D/A converters with 8-bit resolution in the NT68F62. All of these D/A (DAC0 - DAC12) converters are of
open-drain output structure with an external 5V applied maximum. DAC0 – DAC6 are dedicated PWM channels, and DAC7 -
DAC12 are shared with the I/O pins. These 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 a PWM output pin.
The PWM refresh rate is 62.5KHz operating on an 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 the 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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