Z90251 ZILOG [Zilog, Inc.], Z90251 Datasheet - Page 87

• Manufacturer Part Number: Z90251
• Description: eZVision 200 Television Controllers with OSD
• Manufacturer: ZILOG [Zilog, Inc.]

9.3
Digital/Analog Conversion with PWM
The televison OSD controller can generate square waves which have fixed
periods but variable duty cycles. If this type of signal passes through an RC
integrator, the output is a DC voltage proportional to the pulse width of the square
wave. Refer to Figure 20, Cases A and B show fixed voltage samples while Case
C shows a varying voltage example.
Figure 20 Analog Signals Generated from PWM Signals
Case A
Case B
Case C
PWM Signal
PWM Signal
PWM Signal
PWM Signal
32 KB Television Controller with OSD
V
V
V
CC
CC
CC
Voltage
Voltage
Voltage
DC Signal
DC Signal
DC Signal
DC Signal
Time
Time
Time
PS001301-0800
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