ELM701

Elm Electronics – Circuits for the Hobbyist

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Pin Descriptions

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............................... ELM701P

200 mil SOIC..................................... ELM701SM

2 of 3

Absolute Maximum Ratings

Storage Temperature....................... -65°C to +150°C

Ambient Temperature with

Power Applied....................................-40°C to +85°C

Voltage on any other pin with

Note:

Stresses beyond those listed here will likely damage

the device. These values are given as a design

guideline only. The ability to operate to these levels

is neither inferred nor recommended.

All rights reserved. Copyright ©1999 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.

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.

in1, in2, in3, and in4

(pins 2, 3, 4, and 5 respectively)

These are CMOS input pins that are not used in

this design. Due to the nature of CMOS circuitry,

however, they can cause severe overheating,

and battery consumption is left floating. For this

reason all four of these pins must be connected

OUT1 and OUT2 (pins 6 and 7)

These are the actual output piezo drive pins.

Polarity is not important for either the piezo

element or for the ELM701, but there must be a

series

resistor

installed

in

one

of

the

connections. This resistor both limits the volume

of the sound produced, and also limits the piezo

current on energization. (the piezo element

appears as a relatively large capacitive load, so

requires a means to limit the charging current).

See the Electrical Characteristics for resistor

sizes.

Circuit common is connected to this pin. This is

the most negative point in the circuit.

ELM701DSB