HIGH TECH
CHIPS, INC.
04/30/00 1
PDIP, SOIC
1
2
3
8
7
6
5
4
HTC750XXX
VDD GND
NU MOUT
NU CNTL
D1 D0
Melody Generator
1.0
General description
.
This circuit is designed to work as melody generator. HTC750 will play selected melody (selection is
done by driving D0 and D1 inputs to low or high value) and once melody is finished it will enter power
saving mode which we call Sleep mode. In Sleep mode HTC750 consumes less then few microamps
of current. One of possible uses of HTC750 is designing it in doorbell. This device was designed
using our proprietary melody storing scheme to optimize
internal memory usage. HTC750 can play up to four melodies.
It can directly drive piezo-electrical sound source or with use of
external amplifier can drive speakers. Control output is
provided to control external relay or power switch. This output
goes high for duration of melody and could be used to control
the power to HTC750 and amplifier for duration of melody.
Possible uses are:
Musical doorbell.
Melody generator for alarm clock.
Musical toys.
Musical boxes for gifts, accessories or jewelry.
Features:
Single chip solution.
Minimum external components.
Four selectable melodies.
Minimum power consumption while in SLEEP mode.
Doorbell design using HTC750
C1
0.1uF
R3
1K
4.5V
BT1
Q1
NPN
Q2
PNP
LS1
8ohm
C3
47uF
1
2
4
3
R2
100K
R1
100K
U1
HTC750
NU
NU
2
3
MOUT
7
VDD
1
CNTL
6
D1
D0
4
5
GND
8
S1