NEC 78014Y Series, User Manual

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189
CHAPTER 8 16-BIT TIMER/EVENT COUNTER
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 8-12 is as follows.
16-bit compare register (CR00) value
V
AN
= V
REF
×
2
16
V
REF
: External switching circuit reference voltage
Figure 8-12. Example of D/A Converter Configuration with PWM Output
Figure 8-13 shows an example in which PWM output is converted to an analog voltage and used in a voltage
synthesizer type TV tuner.
Figure 8-13. TV Tuner Application Circuit Example
TO0/P30 Switching circuit
PWM signal
V
REF
Low-pass filter
Analog output (V
AN
)
PD78014,78014Y
µ
PD78014,78014Y
TO0/P30
2SC
2352
PC574J
V
SS
GND
Electronic
Tuner
0.22 F 0.22 F 0.22 F
100 pF
8.2 k
Ω
8.2 k
Ω
22 k
Ω
47 k
Ω
47 k
Ω
47 k
Ω
+110 V
µ
µ
µ µ µ