how can I get high absolution(such 8bit) DAC use 16bit PWM ?

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I want to use mcu's 16bit pwm for 8bit DA converter,can I get such absolution?
If I want to get high precision,I must do with following question,but how to solute it?
1、if mcu have 5V power supply,then mcu pwm port output isn't 5V,maybe 4.7~4.9V,it can not get precise output voltage.
2、how can I to filte high ripple?If I use too large time filter,it will reduce dac speed.

 

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Re: how can I get high absolution(such 8bit) DAC use 16bit P

Anyone can offer some reference?
how can I to do with ripple?

and,following sch is a sample,but I think high voltage PC1-T1out from mcu is not equal vcc,and low voltage is not equal zero too.how can I to get precise high voltage and low voltage?