ELM446

Elm Electronics – Circuits for the Hobbyist

< http://www.elmelectronics.com/ >

Connection Diagram

PDIP and SOIC

(top view)

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

reset

1Hz