ELM446
50Hz Generator
Description
The ELM446 is an 8 pin digital divider integrated
circuit, that provides both 50Hz and 1Hz outputs
from a common 3.58MHz NTSC colourburst crystal.
Externally, the designer need only provide the
crystal and two appropriate loading capacitors, as
well as a suitably bypassed power supply. Internal
oscillator circuits then use this reference frequency
to precisely derive a stable 50Hz signal. For
convenience, a complementary 50Hz signal is also
provided. This signal is then further divided to
provide a 1Hz signal output.
A reset input is provided to restart the internal
counters, if desired. An active low signal on this pin
will also force all of the outputs to an open or tristate
condition.
Features
• Low power CMOS design
• Wide supply range - 3.0 to 5.5 volt operation
• 3.58MHz crystal controlled operation
• Generates both 50Hz and 1Hz references
• Low parts count
• Complementary 50Hz outputs
• High current drive outputs - up to 25 mA
Connection Diagram
PDIP and SOIC
(top view)
Applications
• Stable 50Hz reference
• Master oscillator for clock / timekeeping functions
• Decimal based time reference for easier period
calculations
V
DD
XT1
XT2
reset
1
2
3
4
8
7
6
5
V
SS
1Hz
50Hz
50Hz
Block Diagram
V
DD
reset
4
Master
Oscillator
XT1
XT2
2
Divider
÷ 50
7
1Hz
6
50Hz
3
5
50Hz
ELM446DSB
Elm Electronics – Circuits for the Hobbyist
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