
ELM446
< http://www.elmelectronics.com/ >Connection Diagram
PDIP and SOIC
(top view)
V
DD
V
SS
1
2
3
4
8
7
6
5
50Hz Generator
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.
XT1
XT2
Description
Stable 50Hz reference
Master oscillator for clock / timekeeping functions
Decimal based time reference for easier period
calculations
Applications
Block Diagram
1 of 3
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
Features
ELM446DSB
1Hz
50Hz
reset
50Hz
2
3
XT1
XT2
5
50Hz
50Hz
Master
Oscillator
Divider
÷ 50
7
6
4
V
DD
reset
1Hz