ELM ELM307SM, ELM307P Datasheet

ELM307

Camera Control

Description

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5

5

7

4

6

2PW3

Features

The ELM307 is a retriggerable one-shot circuit
that has been designed for electronically controlling
the shutter of a film or digital still camera. The circuit
provides a variable pulse width timer, a variable
delay reset timer, power control, and an LED status
drive all in an 8 pin package.

In operation, a monitored signal (alarm contact,
audio signal, oscillator signal, etc.) is applied to the
circuit’s Trigger input. A low level at this input
immediately causes an output at the Camera pin
(controlling the shutter) that lasts for the duration set
by PW. Further triggering is inhibited until an
additional period (set by Delay) passes, allowing
time for the film to advance or for the digital image to
be stored.

To help with setup, the circuit has a test mode in
which the Camera output is blocked, and the LED is
instead energized. Toggling between the test mode
and the run mode is accomplished with the single
pushbutton input, as is the power on and off.

Applications

• Security camera control

• Candid shots of animals or people

• Low power CMOS design - typically 1mA at 5V

• No external timing elements required

• Test mode assists with setup

• Single pushbutton control

• Auto power off saves batteries

• LED output shows status

• High current drive outputs - up to 25mA

Connection Diagram

PDIP and SOIC

(top view)

VDD VSS

CameraDelay

PW

PB

LED
Trigger

• Time lapse photography

• Remote triggering of cameras

Block Diagram

Trigger

PB

ELM307DSA

VDD

Delay

Delay
Timer

Pulse

Generator

Control

Logic

LED

Logic

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Camera

LED

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ELM307

Pin Descriptions

VDD (pin 1)

This pin is the positive supply pin, and should
always be the most positive point in the circuit.
Internal circuitry connected to this pin is used to
provide power on reset of the microprocessor, so
an external reset signal is not required. Refer to the
Electrical Characteristics section for further
information.

Delay (pin 2)

The logic level at this input pin determines the
minimum time between Camera outputs. A high
level sets a nominal delay of 5 seconds while a low
level gives 1/2 of a second. This delay is provided
to ensure that the camera has time to prepare for
the next picture, before another cycle is allowed.

PW (pin 3)

The digital level at this pin sets the pulse width of
the output at Camera (pin 7). When at a logic low
level, the time will nominally be 1/4 of a second,
while a high level provides 1 second.

will pulse briefly every second, to assist in counting
time. Once a command is acknowledged, a long
LED pulse will be provided so that you know a
change is to occur.

Trigger (pin 5)

A low level at this input initiates one cycle of circuit
operation. The use of a schmitt trigger on the input
means there are no restrictions on the rise or fall
time of the waveform.
If no trigger pulse occurs after 8 minutes in the test
mode or 32 minutes in the run mode, the circuit will
automatically power itself off.

LED (pin 6)

This output is periodically driven to a high level to
show the various states. If in the test mode, LED
will output a double pulse every 4 seconds, while in
the run mode, a single output occurs every 8
seconds. A Camera output will always blank the
LED output, so the LED cannot affect the picture.

PB (pin 4)

This input is to be connected to a momentary action
spst pushbutton switch. Holding the switch closed
for more than 5 seconds will cause the power to
toggle on (if off), or off (if presently on). If the switch
is released after 2 seconds, but before 4 seconds
pass, the mode will toggle between run and test.
Power up is always to the test mode.
While the switch is being pressed, the LED output

Camera (pin 7)

This output is used to control the camera’s shutter.
Usually a transistor provides the actual interface
between the camera and the ELM307 (see the
Example Applications).

VSS (pin 8)

Circuit common is connected to this pin. This is the
most negative point in the circuit.

Ordering Information

These integrated circuits are available in either the 300 mil plastic DIP format, or in the 200 mil SOIC surface

mount type of package. To order, add the appropriate suffix to the part number:

300 mil Plastic DIP............................... ELM307P 200 mil SOIC.....................................ELM307SM

All rights reserved. Copyright ©2001 Elm Electronics.
Every effort is made to verify the accuracy of information provided in this document, but no representation or warranty can be

given and no liability assumed by Elm Electronics with respect to the accuracy and/or use of any products or information
described in this document. Elm Electronics will not be responsible for any patent infringements arising from the use of these
products or information, and does not authorize or warrant the use of any Elm Electronics product in life support devices and/or
systems. Elm Electronics reserves the right to make changes to the device(s) described in this document in order to improve
reliability, function, or design.

ELM307DSA

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