NEC PD78052 - Example of D;A Converter Configuration with PWM Output; TV Tuner Application Circuit Example

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CHAPTER 8 16-BIT TIMER/EVENT COUNTER
PD78054, 78054Y µ
TO0/P30
V
SS
8.2 k Ω
8.2 k Ω
100 pF
22 k
Ω
+110 V
2SC
2352
47 k Ω 47 k Ω 47 k Ω
0.22 F µ 0.22 F µ 0.22 F µ
Electronic
Tuner
GND
PC574J µ
Switching Circuit
TO0/P30
PWM
signal
V
REF
Low-Pass Filter
Analog Output (V
AN )
PD78054, 78054Y µ
By integrating 14-bit resolution PWM pulses with an external low-pass filter, they can be converted to an analog
voltage and used for electronic tuning and D/A converter applications, etc.
The analog output voltage (V
AN) used for D/A conversion with the configuration shown in Figure 8-14 is as follows.
VAN = VREF ×
2
16
VREF: External switching circuit reference voltage
Figure 8-14. Example of D/A Converter Configuration with PWM Output
capture/compare register 00 (CR00) value
Figure 8-15 shows an example in which PWM output is converted to an analog voltage and used in a voltage
synthesizer type TV tuner.
Figure 8-15. TV Tuner Application Circuit Example