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LM567Phase-locked-loop tone decoder
Recognize a tone and turn it into a clear logic signal.
LM567C uses a phase-locked loop to recognize a tone near an externally selected frequency. When a sufficiently strong signal lies inside its detection band, an internal output transistor turns on and pulls OUT low. A pull-up resistor supplies the released HIGH state. A resistor between pins 5 and 6 and a capacitor from pin 6 to ground set the nominal center frequency. Separate capacitors at pins 2 and 1 set loop filtering and output response; they do not replace the timing capacitor. This page covers the LM567CN/NOPB and LM567CM/NOPB commercial parts, rated from 0 to 70°C. The illustrated 5 V circuit uses 10 kΩ and 100 nF for approximately 909 Hz. Component tolerances, signal amplitude, filters and settling determine actual detection.
8Physical pins
LM567CN/NOPBPDIP-8
Manufacturer-referencedTexas Instruments
Pin diagram
Select a pin to explore its connection
Highlight
LM567PDIP-8Top view
LM567SOIC-8Top view
Click a lead or use the arrow keys. Top view
PIN 1 · Filter capacitors
Output filterOF_CAP
Function
Sets output filtering and detection delay.
How to connect
Connect 2.2 µF to ground; positive end at pin 1.
Electrical note
Use C3 at least twice the loop-filter capacitor in the illustrated design.
PIN 2 · Filter capacitors
Loop filterLF_CAP
Function
Filters the phase-locked-loop control signal.
How to connect
Connect 1 µF to ground; positive end at pin 2.
Electrical note
This capacitor affects capture bandwidth and response time.
PIN 3 · Tone input
Analog tone inputIN
Function
Accepts the tone to be detected.
How to connect
Feed the grounded signal generator through a 100 nF series capacitor.
Electrical note
Use 100 mV RMS near 909 Hz for this example, not a rail-level digital signal.
PIN 4 · Supply
Positive supplyVCC
Function
Powers the decoder circuitry.
How to connect
Connect regulated +5 V, with 100 nF and 1 µF local bypass to ground.
PIN 5 · Oscillator timing
Timing resistorT_RES
Function
One side of the oscillator timing resistor.
How to connect
Connect R1 = 10 kΩ between pins 5 and 6.
Electrical note
The resistor goes between these pins, not from pin 5 to VCC.
PIN 6 · Oscillator timing
Timing capacitorT_CAP
Function
Oscillator timing node.
How to connect
Connect C1 = 100 nF to ground, and the other end of R1 from pin 5.
Electrical note
Use stable timing parts and short traces.
PIN 7 · Ground
Ground returnGND
Function
Common supply and signal return.
How to connect
Join supply negative, filter returns and signal-generator ground.
PIN 8 · Detection output
Open-collector outputOUT
Function
Sinks current when a sufficient signal is detected in the passband.
How to connect
Add a 10 kΩ pull-up to +5 V and read with a high-impedance meter.
Electrical note
LOW means detected. Without the pull-up, the released output is not driven HIGH.
Key specifications
The oscillator and phase detectors track an input near the selected center. External filters determine how quickly and selectively the output responds.
Operating supply3.5–8.5 V · 5 V example
Example center909 Hz · nominal
Selected ambient0–70 °C · CN / CM
Detection outputLOW Open collector · add pull-up
Package details
LM567CN/NOPB · PDIP-8
| Property | Details |
|---|---|
| Manufacturer | Texas Instruments |
| Part number | LM567CN/NOPB |
| Package | PDIP-8 |
| Connections | 8 pins |
| Mounting | Through-hole |
| Lead pitch | 2.54 mm |
| Package code | dip |
| Thermal reference | θJA 53.0°C/W · manufacturer thermal table |
Supply and signal reference
LM567C · 5 V / 25°C electrical tests
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Operating supply | 3.5–8.5 V | Recommended operating table; use 5 V for the example |
| Selected ambient | 0 to +70°C | CN / CM ordering options |
| Quiescent supply current | 7 mA typical; 10 mA maximum | RL = 20 kΩ |
| Activated supply current | 12 mA typical; 15 mA maximum | RL = 20 kΩ |
| Input resistance | 15 kΩ minimum; 20 kΩ typical | Tone input pin 3 |
| Smallest detected input | 20 mV RMS typical; 25 mV RMS maximum | Input at center frequency; manufacturer IL = 100 mA condition |
No specifications match. Try a parameter name or a unit.
Detection depends on frequency, amplitude, filtering and the manufacturer test conditions.
Timing and selectivity
External components define the application
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Approximate center frequency | 1 / (1.1 × R1 × C1) | R in ohms; C in farads; result in hertz |
| Timing resistor | Pins 5 to 6 | 10 kΩ in the example |
| Timing capacitor | Pin 6 to ground | 100 nF in the example |
| Highest center frequency | 100 kHz minimum; 500 kHz typical | 500 kHz is not a guaranteed limit for every unit |
| Largest detection bandwidth | 14% typical; 10–18% limits | Maximum-setting test; not the width of every filter network |
| Fastest on/off cycling | f₀ / 20 typical | Reference condition, not instantaneous detection |
No specifications match. Try a parameter name or a unit.
R/C tolerance shifts the center; filter values and signal amplitude determine the usable detection band.
Open-collector output
Pin 8 sinks current on detection
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Output LOW at 30 mA | 0.2 V typical; 0.4 V maximum | 25 mV test input |
| Output LOW at 100 mA | 0.6 V typical; 1.0 V maximum | 25 mV test input |
| Output leakage | 0.01 µA typical; 25 µA maximum | Output at 15 V |
| Output rise / fall time | 150 ns / 30 ns typical | Electrical test circuit |
| Example pull-up | 10 kΩ to +5 V | Less than 0.5 mA when LOW |
| Released output | HIGH through the pull-up | The IC does not actively source that HIGH voltage |
No specifications match. Try a parameter name or a unit.
Large sink currents increase power dissipation; the lightly loaded example avoids that condition.
909 Hz detector example
Grounded signal generator and regulated 5 V
Manufacturer specifications 7 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Input tone | 100 mV RMS near 909 Hz | AC-coupled through 100 nF to pin 3 |
| R1 / C1 | 10 kΩ / 100 nF | R1: 5–6; C1: 6–ground |
| C2 loop filter | 1 µF | Pin 2 to ground; positive at the pin |
| C3 output filter | 2.2 µF | Pin 1 to ground; at least 2 × C2 |
| Supply bypass | 100 nF + 1 µF | Across pins 4 and 7, near the package |
| Output reading | LOW after detection settles | High-impedance meter on pin 8 |
| Nominal arithmetic | 909.1 Hz | 1 / (1.1 × 10000 × 100 × 10⁻⁹) |
No specifications match. Try a parameter name or a unit.
This is an illustrative tuned detector, not a specified instrument. Sweep and calibrate the assembled circuit.
Package and stress limits
LM567CN/NOPB · PDIP-8
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Pitch / mounting | 2.54 mm | Through-hole |
| Package numbering | 8 physical pins | Top view; counterclockwise from the marker |
| Supply stress limit | 9 V absolute maximum | Do not confuse with 8.5 V recommended maximum |
| Output stress limit | 15 V at pin 8 | External collector voltage; observe dissipation |
| Storage | −65 to +150°C | Unpowered |
| Layout | Short timing and filter returns | Separate output-load currents from the sensitive input path |
No specifications match. Try a parameter name or a unit.
Absolute ratings are stress boundaries. The downloadable land pattern must be checked against the chosen assembly process.
Connections by function
Select a pin for its function, connection guidance and electrical notes.
Filter capacitors2 pins
Tone input1 pin
Supply1 pin
Oscillator timing2 pins
Ground1 pin
Detection output1 pin
Filter capacitors2 pins
Tone input1 pin
Supply1 pin
Oscillator timing2 pins
Ground1 pin
Detection output1 pin
LM567 at a glance
Follow the labeled connections and functional stages
How it works
3 stages · Explore one step at a time
Choose the center frequency
Use f₀ ≈ 1 / (1.1 × R1 × C1). With 10 kΩ and 100 nF, the nominal center is 909.1 Hz.
Filter the detector signals
The 1 µF loop capacitor and 2.2 µF output capacitor reduce unwanted responses. Larger filter capacitance generally trades faster response for stronger filtering.
Read active-LOW detection
A settled, sufficient tone near the center turns the output transistor on. The 10 kΩ pull-up limits sink current to less than 0.5 mA at 5 V. Out of band, it releases the output.
Step 1 of 3
LM567 in a circuit
A physical eight-pin decoder with a complete timing and filter network.
Connect it, step by step
Follow the component values and pin connections
Wire the timing pair
R1 joins pins 5 and 6; C1 joins pin 6 to ground.
Add the filters and power
Fit C2 at pin 2, C3 at pin 1 and both bypass capacitors across the 5 V supply.
Apply and sweep the tone
Use a grounded signal generator, start near 909 Hz and observe the active-LOW output after settling.
Inside LM567
Oscillator, phase detection and a filtered output in one compact IC.
Explore the circuit
Select a stage to see its role and connections
Generate a local reference
R1 and C1 set the VCO timing near the desired tone.
Compare phase and amplitude
I/Q detector paths identify the signal and close the filtered control loop.
Drive the collector
The output filter controls the detection response before the transistor sinks pin 8.
Selected packagePDIP-8LM567CN/NOPB
Physical connections8 pinsPackage-specific numbering
Reference collection6 tables31 parameters & pin functions
Pin reference
Signal names, electrical functions and connection guidance
Physical pin numbers8 pins
Scroll within the table to see all columns and rows.
| Pin | Signal | Type | Function & connection |
|---|---|---|---|
| OF_CAP | Output filter | Sets output filtering and detection delay.Connection guidanceConnect 2.2 µF to ground; positive end at pin 1. Use C3 at least twice the loop-filter capacitor in the illustrated design. | |
| LF_CAP | Loop filter | Filters the phase-locked-loop control signal.Connection guidanceConnect 1 µF to ground; positive end at pin 2. This capacitor affects capture bandwidth and response time. | |
| IN | Analog tone input | Accepts the tone to be detected.Connection guidanceFeed the grounded signal generator through a 100 nF series capacitor. Use 100 mV RMS near 909 Hz for this example, not a rail-level digital signal. | |
| VCC | Positive supply | Powers the decoder circuitry.Connection guidanceConnect regulated +5 V, with 100 nF and 1 µF local bypass to ground. | |
| T_RES | Timing resistor | One side of the oscillator timing resistor.Connection guidanceConnect R1 = 10 kΩ between pins 5 and 6. The resistor goes between these pins, not from pin 5 to VCC. | |
| T_CAP | Timing capacitor | Oscillator timing node.Connection guidanceConnect C1 = 100 nF to ground, and the other end of R1 from pin 5. Use stable timing parts and short traces. | |
| GND | Ground return | Common supply and signal return.Connection guidanceJoin supply negative, filter returns and signal-generator ground. | |
| OUT | Open-collector output | Sinks current when a sufficient signal is detected in the passband.Connection guidanceAdd a 10 kΩ pull-up to +5 V and read with a high-impedance meter. LOW means detected. Without the pull-up, the released output is not driven HIGH. |
No pins match these filters. Try another signal name or reset the filters.
Supply and signal reference
LM567C · 5 V / 25°C electrical tests
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Operating supply | 3.5–8.5 V | Recommended operating table; use 5 V for the example |
| Selected ambient | 0 to +70°C | CN / CM ordering options |
| Quiescent supply current | 7 mA typical; 10 mA maximum | RL = 20 kΩ |
| Activated supply current | 12 mA typical; 15 mA maximum | RL = 20 kΩ |
| Input resistance | 15 kΩ minimum; 20 kΩ typical | Tone input pin 3 |
| Smallest detected input | 20 mV RMS typical; 25 mV RMS maximum | Input at center frequency; manufacturer IL = 100 mA condition |
No specifications match. Try a parameter name or a unit.
Detection depends on frequency, amplitude, filtering and the manufacturer test conditions.
Timing and selectivity
External components define the application
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Approximate center frequency | 1 / (1.1 × R1 × C1) | R in ohms; C in farads; result in hertz |
| Timing resistor | Pins 5 to 6 | 10 kΩ in the example |
| Timing capacitor | Pin 6 to ground | 100 nF in the example |
| Highest center frequency | 100 kHz minimum; 500 kHz typical | 500 kHz is not a guaranteed limit for every unit |
| Largest detection bandwidth | 14% typical; 10–18% limits | Maximum-setting test; not the width of every filter network |
| Fastest on/off cycling | f₀ / 20 typical | Reference condition, not instantaneous detection |
No specifications match. Try a parameter name or a unit.
R/C tolerance shifts the center; filter values and signal amplitude determine the usable detection band.
Open-collector output
Pin 8 sinks current on detection
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Output LOW at 30 mA | 0.2 V typical; 0.4 V maximum | 25 mV test input |
| Output LOW at 100 mA | 0.6 V typical; 1.0 V maximum | 25 mV test input |
| Output leakage | 0.01 µA typical; 25 µA maximum | Output at 15 V |
| Output rise / fall time | 150 ns / 30 ns typical | Electrical test circuit |
| Example pull-up | 10 kΩ to +5 V | Less than 0.5 mA when LOW |
| Released output | HIGH through the pull-up | The IC does not actively source that HIGH voltage |
No specifications match. Try a parameter name or a unit.
Large sink currents increase power dissipation; the lightly loaded example avoids that condition.
909 Hz detector example
Grounded signal generator and regulated 5 V
Manufacturer-referenced values7 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Input tone | 100 mV RMS near 909 Hz | AC-coupled through 100 nF to pin 3 |
| R1 / C1 | 10 kΩ / 100 nF | R1: 5–6; C1: 6–ground |
| C2 loop filter | 1 µF | Pin 2 to ground; positive at the pin |
| C3 output filter | 2.2 µF | Pin 1 to ground; at least 2 × C2 |
| Supply bypass | 100 nF + 1 µF | Across pins 4 and 7, near the package |
| Output reading | LOW after detection settles | High-impedance meter on pin 8 |
| Nominal arithmetic | 909.1 Hz | 1 / (1.1 × 10000 × 100 × 10⁻⁹) |
No specifications match. Try a parameter name or a unit.
This is an illustrative tuned detector, not a specified instrument. Sweep and calibrate the assembled circuit.
Package and stress limits
LM567CN/NOPB · PDIP-8
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Pitch / mounting | 2.54 mm | Through-hole |
| Package numbering | 8 physical pins | Top view; counterclockwise from the marker |
| Supply stress limit | 9 V absolute maximum | Do not confuse with 8.5 V recommended maximum |
| Output stress limit | 15 V at pin 8 | External collector voltage; observe dissipation |
| Storage | −65 to +150°C | Unpowered |
| Layout | Short timing and filter returns | Separate output-load currents from the sensitive input path |
No specifications match. Try a parameter name or a unit.
Absolute ratings are stress boundaries. The downloadable land pattern must be checked against the chosen assembly process.
No matching rowsTry a pin name, parameter, unit or test condition, or reset the filters.
Tone-presence indicators
Detect a known audio tone and provide a logic flag after the filtering delay.
Manufacturer application guideFrequency monitoring
Monitor whether a signal lies near a calibrated center frequency.
Manufacturer application guideSelective signaling
Use separately tuned channels for distinct tones, with attention to interference and filter response.
Manufacturer application guideTake it into ProTech
Find LM567 in the Components Library to place its schematic symbol and connect its pins.
Reference page · circuit simulation model not yet availableOpen ProTech