A PWM signal,produced by STM32F103,which frequence is 7200 Hz and amplitude is less than 3.3V.
I use CD74HC4053 to select signal channel,Channel0 is PWM signal,Channel1 is GROUND(0V).circuit as shown in figure.
when S0 S1 S2 be set to LOW,I can get PWM signal from the output pin,and if S1 S2 are LOW and S0 is High,the output is 0V voltage.
S0 is controlled by PB0(50MHz) of STM32.
when I disconnect PB0 to S0, the rise time of PB0 is less than 5ns,the question is that the rise time longer,why when I connect PB0 to S0,even more than 100ns.
I want to use GPIO selection signal,but subsequent IC must not change rise time and fall time.
Coule you give me some better solution?
I can accept the range of rise time: < 100 ns
the output current:10mA ~ 30mA
