sm1350 Nippon Precision Circuits Inc, (NPC), sm1350 Datasheet - Page 14

• Manufacturer Part Number: sm1350
• Description: High Tone Quality Melody Lsi
• Manufacturer: Nippon Precision Circuits Inc, (NPC)

One-shot mode perpetual repeat function
If the score ROM end code is set to the jump code, the melody will continue to play continuously once one-
shot mode starts.
STOP pin
One-shot output mode stops when STOP goes from HIGH to LOW. The STOP input is ignored in level hold
output mode and is also ignored in one-shot mode when STN is LOW. Note that even when STOP is LOW,
STN has higher priority.
CT pin
A pulse in sync with selected notes or rests is output on CT. There are 2 modes for the output pulses
mode and hold mode.
Pulse mode
In pulse mode, a 16.4 ms pulse is output when a note or rest occurs for which the corresponding CT data in
score ROM is set to 1.
Hold mode
In hold mode, the output pulse inverts when a note or rest occurs for which the corresponding CT data in score
ROM is set to 1. The output goes LOW after the start of a melody and when jumping to the leading note of a
melody.
Fast Damping
When melody output stops, the D/A converter output amplitude does not fall to zero instantaneously, instead
the output converges to zero within a maximum of 8.2 ms to prevent noise being generated. Also, when one-
shot melody output mode is retriggered, melody output restarts after the fast damping interval.
CT DATA
CT DATA
CT
CT
STOP
Melody
Output
Note: Refer to the "TIMING DIAGRAMS" section to confirm melody timing specifics.
1
1
16.4msec
Figure 13. CT pulse mode output
Figure 14. CT hold mode output
Figure 15. Fast damping timing
1
1
0
SM1350 series
0
1
1
8.2msec (max)
NIPPON PRECISION CIRCUITS INC.—14
1
1
0
0
−
pulse