Another versatile device, the IC 4060 has numerous applications and can be used for implementing various useful functions in an electronic circuit.
Introduction
Basically the IC 4060 is a oscillator/Timer IC and can be used for producing discretely variable accurate time intervals or delays. Alternatively it may also be used as an oscillator for acquiring high grade, accurate time period oscillations of frequencies.
The best thing about this chip is that it has an in-built oscillator module which requires just a few external components for initiating the oscillations.
Thus the IC is not dependant on any external clock input.
Parts List
R1 = 2M2
P1 = 1M pot
R2 = 100K
C1 = 1uF/25V
Understanding Pinout Functions of IC 4060
Let’s try to understand the pin outs of the IC 4060 in simple terms:
Referring to the figure we see that the only input pinouts which are required to be configured with external parts are pin # 9, 10, 11, and 12.
All the remaining pinouts are the output pins of the IC, except pin#16 and pin#8 which are Vcc (+) and the Vss (-) supply pinouts respectively.
The output pinouts are 7, 5, 4, 6, 14, 13, 15, 1, 2, 3 which are assigned for producing the ON/OFF time delays, or the clock signal outputs, or the oscillations, or the frequency at different levels depending on the values of the resistor Rt and the capacitor Ct on pin#10/9 of the IC respectively.
Pin #7 generates the highest value of frequency, while pin #3 produces the least.
For example, suppose the resistor/capacitor values at pin#9/10 causes pin # 7 to generate a frequency of 1MHz, then pin #5 would generate a frequency of 500 Khz, pin # 4 would generate 250 Khz, pin #6 would generate 125KHz, pin #14 would generate 62.5 KHz and so on.
As you may notice the frequency goes on becoming half in proportion, and this happens with the pinout order of 7, 5, 4, 6, 14, 13, 15, 1, 2, 3, wherein pin#7 produces the highest frequency, while pin#3 the minimum.
As mentioned earlier, the above frequency or oscillations can be initiated or setup by connecting a few passive components at pin#9, 10 and 11 of the IC as shown in the figure, it’s that simple.
How to Adjustable Timing
The variable resistor Rt could be replaced with a potentiometer at pin#10 of the IC 4060 to get an adjustable frequency output across the mentioned output pins of the IC. Alternatively, the capacitor Ct value may also be altered for changing the frequency of the IC.
How to Connect the Reset Pin
Pin #12 is the reset input and should always be grounded or connected to the negative supply.
A positive supply pulse to this input will reset the oscillations or revert the IC so that it begins counting or oscillating from the zero, causing all the outputs to switch to zero logic.
How to Achieve an Automatic Power Switch ON Reset
Enabling an automatic power switch ON resetting of a timer IC such as IC 4060 becomes crucial in order to initiate the IC clock, and counting process from zero.
If an auto reset facility is not included, the IC could exhibit a random or a haphazard initialization of its counting process, which may not be from the zero or start, rather from any intermediate level.
Therefore to ensure an automatic resetting for the IC, we must include an RC network with the reset pinout ofthe IC as explained below:
Instead of connecting the pin#12 directly to ground line, connect it through a high value resistor such as a 100K.
Then attach a small value capacitor from positive to pin#12, the value could be anywhere from 0.33uF to 1uF.
That's it, now your IC 4060 timer circuit is enabled with an auto reset feature, and will always initiate with a stable start, from zero.
Enabling a Manual Reset Action
To achieve a manual resetting facility in any IC 4060 circuit, you can simply replace the capacitor with a push button, as shown above.
Pressing this button anytime during the counting process of the IC, will quickly reset the IC to zero, so that the counting can start afresh from zero.
Calculating the Timing RC Component Values
The image below shows the magnified section of the IC containing the oscillator pin#9, 10, 11.
The Rt and Ct are the main timing components which are actually responsible for determining the various delay intervals or frequencies across the IC outputs.
How the Oscillator Works
Referring the the below show internal configuration, we can see that the timing parts Rt, and Ct are configured around a NAND gate and NOT gate, in a classic logic astable stage.
The standard formula for calculating the Rt and Ct values is:
f(osc) = 1 / 2.3 x Rt x Ct
2.3 is a constant as per the ICs internal configuration.
The oscillator will essentially work normally only when the selected values satisfy the conditions:
Rt << R2 and R2 x C2 << Rt x Ct.
R2 is positioned to reduce the frequency effect of the forward voltage over the input protection diodes.
C2 depicts the stray capacitance and is supposed to be minimal for enabling greater accuracy of the output time intervals.
For this, Ct must be relatively larger than C2, the larger the better.
Rt must be also a rather large value to negate the internal LOCMOS resistance, which appears in series with Rt internally.
Its typically value is around is 500 Ω at VDD = 5 V, 300 Ω at VDD = 10 V and 200 Ω at VDD = 15 V.
In order ensure a proper oscillatory action the most recommended values of the above mentioned timing parts must be configured as per the following conditions:
- Ct ≥ 100 pF, up to any workable value,
- 10 kΩ ≤ Rt ≤ 1 MΩ.
Supply Pins
Pin #16 is the positive of the IC and pin #8 is the negative supply input of the IC.
Using IC 4060 with Crystal Oscillator
Although the IC 4060 itself is fairly accurate with its frequency of oscillation and delay periods, this can be further enhanced using an externally crystal device with the IC.
A crystal based oscillator will enable locking of the frequency to the predetermined value, and prevent any form drifting from the intended value.
The following diagram shows how to connect a crystal device with the IC 4060 for achieving a constant and accurate frequency output:
As we can see in the above figure, only the pin11 and pin10 are used for the integrating the crystal with the IC. R2 is used for initiating the crystal oscillations by supplying the required voltage pulses to the crystal.
C3 and C2 enable the crystal to reach its rated resonance frequency. C3 can be tweaked to change this resonance value of the crystal slightly, and therefore the output frequency of the IC 4060 accordingly.
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