HD404654 Datasheet, PDF (81/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

TONER
VT _ref
TONEC
Sine wave
counter D/A
Feedback
Transforma-
tion program
divider
TONER output control
Sine wave
counter D/A
Feedback
Transforma-
tion program
divider
HD404654 Series
2
Tone generator
mode register
(TGM)
Tone generator
2
control register
(TGC)
TONEC output control
f _{OSC 400 kHz}
800 kHz
1/2
2 MHz
1/5
3.58 MHz
1/9
4 MHz
1/10
400 kHz
Selector
2
System clock
selection register 1
(SSR1)
System clock
selection register 2
(SSR2)
1
Figure 64 Block Diagram of DTMF Generator Circuit
79