CF1155 Datasheet, PDF (5/7 Pages) Nippon Precision Circuits Inc – Melody LSIs

CF1155 series
Power-save Function
As shown in the preceding timing diagrams, the oscillator stops during non-play mode and the pull-down resis-
tance value changes in response to both HIGH-level and LOW-level inputs (power-save pull-down resistor) to
reduce power consumption and extend battery life.
Non-play oscillator stop function
When melody play ends, regardless of the state of either LH or OSH, the internal oscillator stops and is placed
in a standby state. In this state, the current consumption, including input pin pull-down resistor current (I_IH
max), does not exceed 3.3µA.
Power-save pull-down resistor
The resistance of the OSH and LH input pull-down resistor changes in response to the input voltage. The pull-
down resistance is 1MΩ when the input is HIGH, and the pull-down resistance is 270kΩ when the input is
LOW.
Furthermore, if a light-dependent resistor (CdS) cell is employed as a switch (the pull-down resistance is max-
imum when the CdS resistance is minimum (light) and the pull-down resistance is minimum when the CdS
resistance is maximum (dark)), the combined resistance can be increased, decreasing current consumption.
Musical Specifications
Maximum program steps
A maximum of 64 steps can be programmed into internal mask-programmable ROM. Each step represents
either a note (sound pitch and length), a rest note, or a jump. The maximum number of jumps is 7.
Note length (including rests)
Eight rhythm values, from sixteenth note to half note, for notes and rests can be programmed, as shown in the
following table.
Code
Type
0
1
2
3
4
5
6
7
Note
Rest
Also, notes and rests longer than half notes and rests can be created using a tie to connect the notes. This
requires 2 program steps in ROM.
Tempo
The tempo for the standard quarter note can be selected from the following 16 options.
Code 0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
= 697 348 232 174 139 116 99.4 87 77.3 69.6 63.3 58 53.5 49.7 46.4 43.5
Pitch and scale
The CF1155 series devices support 3.5 octaves ranging from G₃ to D₇, from which 15 notes can be selected to
form a scale.
NIPPON PRECISION CIRCUITS—5