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You are here: Home / Electronic Components / LM567 Tone Decoder IC Features, Datasheet and Applications

LM567 Tone Decoder IC Features, Datasheet and Applications

Last Updated on July 10, 2021 by Swagatam 21 Comments

caution electricity can be dangerous

The post discuses the main specifications, datasheet and working principle of the IC LM567, which is a precise phase-locked loop with synchronous AM lock detection and power output device.

In simpler terms the IC LM567 IC is a tone decoder chip which is designed basically for recognizing a specified frequency band, and activating the output in response to the detection.

Needless to say this chip can be used for a number of different applications, the most common being in the field of remote controls, and security systems.

Block Diagram

Absolute Maximum Rating

Absolute maximum rating refers to the values indicating the maximum tolerable capacity of the IC in terms of voltage, current, and power dissipation. The following table explains the absolute maximum rating of the IC LM567 for the relevant parameters:

Pinout Working and Specifications

Referring to the the above shown IC LM 567 internal configuration diagram, the pinout function of the IC may be understood from the following points:

Pin#4 and Pin#7 are the positive (Vdd) and the negative (Vss) supply inputs respectively for the IC.

Pin#3 is the sensing input of the input, which is used for detecting a given phase-locked loop frequency, in other words this pin will lock-on with the matching center frequency which may be set inside the IC through a pair of external RC network.

The Pin#5 and 6 are used for creating the center frequency by setting up the values of R1, C1 as required, and this frequency is used by the sensing input pin#3 to lock-in and create a logic zero at pin#8 which is the output pin of the IC.

Output Pin#8 is normally logic high and becomes logic zero as soon as a matching frequency is detected at pin#3 of the IC.

Pin#1 and pin#2 are used for ensuring proper filtration of the involved frequencies so that the IC does not create any false output due to any existing spurious or stray noise interferences.

Main Features of LM567:

Extensive settable frequency range (0.01 Hz to 500 kHz), meaning the sensing passband may be set right from 0.1 to 500 kHz, giving an option of a huge range so that unlimited unique configuration can be achieved from this chip.

Highly stable of center frequency, which assures precise passband limits making the unit very reliable with the detection functions.

Independently controllable bandwidth (up to 14%), as the feature suggests, the bandwidth is also adjustable to a reasonable degree.

High out-band signal, and noise rejection, which again assures high reliability during the detection and implementation of the said functions.

Logic-compatible output with 100 mA current sinking capability, which allows the output to handle relatively higher loads without employing an additional buffer stage such as a transistor driver stage.
Inherent immunity to false signals, which ensures that the chip never produces false results due to incorrect frequency detection or in the presence of stray or spurious instantaneous signals.

Frequency adjustment over a 20-to-1 range with an external resistor, this feature again makes the chip highly flexible and dynamic.

The three important Parameters Associated with the IC LM567 may be understood with the following points:

Phase locked loop center frequency

It’s the free running frequency of the in-built current controlled oscillator circuitry in the
absence of an input signal.

Detection Bandwidth

This is the frequency range which may be provided to the above center frequency, within which the presence of an input signal having a threshold voltage of above 20mV  causes the output of the IC to become low. This feature refers to the loop capture range.

Lock Range

It is the maximum range of frequency which would enable the output to switch to logic zero in the presence of a relevant input signal having a threshold voltage above 20mV.

Detection Band

It is the magnitude which indicates the level of optimal detection, focused around the center frequency. It’s given by the formula:

Detection Band = (fmax + fmin – 2fo)/2fo,

where fmax and fmin are the frequencies thresholds of the detection band, fo is the center frequency

Application Hints

The IC567 may be considered as a versatile chip because it provides an unlimited range of applications in the field of electronics, some of them are discussed below:

  1. Touch-Tone decoding: The human touch response may produce different frequencies when employed with this chip, it can be suitably decoded by using many IC LM567 configurations.
  2. Carrier current remote controls: Our existing mains wiring can be very effectively used as a medium of transfer for communicating between the rooms or for controlling appliances remotely from one room to the other. The actions can be implemented by using a LM567 IC.
  3. Infrared controls (remote TV, etc.): Since the center frequency of LM567 is tightly locked, it may be used for detecting IR waves precisely from the given handset. Unlike ordinary IR remote controls, this circuit is better immune to stray RF or IR disturbances created from switching AC mains appliances.
  4. Frequency monitoring and control: Again since the LM567 IC has an inbuilt precise frequency detection range, which can be used for monitoring a given range of frequency accurately.
  5. Wireless intercom: Just like Carrier current remote controls, the IC LM567 may also be suitably  implemented in wireless intercom systems.
  6. Precision oscillator: The phase locked loop feature in the proposed IC also facilitates its application as a precision oscillator for achieving precisely adjusted oscillations or frequencies.

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About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Reader Interactions

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  1. Aaron says

    September 15, 2021

    For some reason, my 20KHz, 4Vp-p, CW tone detector is not working. Signal to Pin 3 is provided by a sig gen. I am using Ct = 0.01uF and Rt = 550 ohm. Pin 4 = 6.0 VDC and Pin 8 has a 10Kohm pullup to 6.0 VDC.

    Pin 8 is always high as I sweep the frequency of Vin. I never see it lock at any freq.

    What value of caps for C2 (Pin 1) and C3 (Pin 2) do you recommend for 14% bandwidth (from what equation)? I’d like to verify this as I can’t figure what else could be the issue. I value any advice you can give.

    Reply
    • Swagatam says

      September 15, 2021

      You can try the following 100kHz test circuit taken from the original datasheet of the IC

      LM567 test circuit\

      Once the basic parameters are confirmed in the above configuration, you can then tweak the relevant parts to achieve your specific results.

      Reply
      • Aaron says

        September 15, 2021

        That’s a good way to start. Thanks for your help.

        Reply
        • Swagatam says

          September 15, 2021

          You are welcome!

          Reply
  2. Vasu says

    June 23, 2020

    Dear Mr. Swagatam,

    I came across your website and it is very interesting.
    Hats off to you for helping others in technical knowledge sharing and your helping nature.

    I need your expertise.. I am designing a IR Proximity Sensor module with LM567 IC
    with preset option (for distance adjustment).

    Can you please guide me with a circuit for it?

    Regards

    Vasu
    Chennai

    Reply
    • Swagatam says

      June 23, 2020

      Thank you Dear Vasu, you can refer to the LM567 proximity circuit under this article.
      https://www.homemade-circuits.com/simple-proximity-sensor-circuit/

      However, the distance for this design is only a few cms, for longer adjustable distance you may have to replace the D2 (BP104) with TSOP1738

      And also make sure to adjust C2 so that frequency of the iC is set to a precise 38 kHz, otherwise the TSOP sensor will not respond.

      For achieving an adjustable feature you can replace R1 with an adjustable 500 ohm preset which will help you adjust the sensitivity of the photodiode transmitter

      Reply
      • Vasu says

        June 23, 2020

        Hello Mr. Swagatam,

        Thanks for your prompt reply and guidance.

        Good Luck!

        Regards,

        Vasu
        Chennai, INDIA

        Reply
  3. Ali Khayri says

    February 9, 2020

    Dear Swag,
    I think the following paragraph is to be corrected in Application Hints no. 3
    Ultrasonic controls (remote TV, etc.): Since the center frequency of LM567 is tightly locked, it may be used for detecting IR waves precisely from the given handset.
    Ultrasonic controls not IR.

    Reply
    • Swagatam says

      February 9, 2020

      Thank you Ali, I have corrected the relevant paragraph.

      Reply
  4. Gustaaf says

    December 8, 2019

    Hi Swagatam,

    I am looking for a device activating a relais when detecting a 4 kHz frequency. I learned from you that LM567 can do that. Is there somewhere also a PCB with all components on it available?

    Thanks,

    Reply
    • Swagatam says

      December 8, 2019

      Hi Gustaf, yes that’s correct, you can probably try and customize the first design from this article, as per your specs:

      https://www.homemade-circuits.com/tuned-infrared-ir-detector-circuit/

      Reply
  5. Phùng Tuấn Hưng says

    November 14, 2019

    dear Swagatam
    i need to make fm modulation circuit with lm567. you have any circuit. please help me
    thanks you!

    Reply
    • Swagatam says

      November 14, 2019

      Sorry Phung, I don’t have this circuit right now with me…

      Reply
  6. Peter van Heerebeek says

    August 31, 2019

    Great summery.
    I was looking for a circuit to detect if any of my fire alarm units was sounding so I could automatically open the window blinds to provide escape routes, and this chip seems perfectly suitable for this job.
    My alarm units beep at 3363Hz so using R=1500 Ohm, C1=220nF, C2=220nF and C3=4.7uF should do.
    Will keep you posted about the result once the mems microphone module, 5V output relay and other parts have arrived and all has been assembled and tested.

    Reply
    • Swagatam says

      August 31, 2019

      Thank you, Glad you found it useful. Will wait for the updates!

      Reply
  7. saman says

    December 4, 2017

    how can i use this ic for making clock pulse

    Reply
    • Swagatam says

      December 4, 2017

      Please refer to this datasheet Figure:18

      http://www.ti.com/lit/ds/symlink/lm567c.pdf

      Reply
  8. Wicky says

    October 2, 2017

    I alread brought a LM567 module as shows in below site
    https://www.homemade-circuits.com/wp-content/uploads/2017/10/LM567.png
    But i need a higher bandwidth. Could somebody help me to figure out what capacitor value i should change.
    Im using center freq as = 815Hz
    as well as 14% bandwidth i prefer
    What value of a capacitor i should choose?

    Reply
    • Swagatam says

      October 2, 2017

      The formula for calculating the RC values is:

      f0 ~ 1.1/RC,

      where R C are the external timing resistor capacitors, f0 is the center frequency

      Reply
  9. rahul says

    May 13, 2014

    dear Swagatam,
    I was trying to buy LM567 online, but i couldn't find on some of the popular sites and I have made a list on one of the sites (of other components to buy). So I want to ask – Is there an alternative for LM567? so that i may continue with the same order from that site with that ic.
    Is BA1604 the correct alternative?
    Purpose is same: as the IC you used in your circuits (ir remote).

    Reply
    • Swagatam says

      May 14, 2014

      Dear Rahul,

      yes you can use it, both are direct equivalents of each other.

      Reply

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