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How to Test 78l05 Voltage Regulator

What is 78L05 Voltage Regulator

78L05 is a fixed voltage (5V) three terminal coordinated controller, which can be applied to numerous applications. Its phenomenal interior present and warm shutdown attributes make it particularly reasonable for over-burden. When it is utilized to supplant the customary zener diode – obstruction gathering, its yield impedance is improved adequately, however the predisposition current is incredibly decreased.

In another words,78L05 arrangement (like L78L05ACD013TR) is a fixed voltage (5V) three terminal coordinated voltage controller, which is appropriate for some applications. Like a solitary point voltage controller which needs to restrict the clamor and take care of the conveyance issue, it can likewise be utilized with other power move gadgets to frame a steady voltage power supply with huge current, for example, a steady yield current of up to 100 mA.

The Features of 78L05

  • input voltage up to 30-35V
  • output current can reach 100mA
  • no external connector
  • internal thermal overload protection
  • internal short circuit current limit
  • from the end of 2004, all types of packaging were lead-free packaging products

78L05 Applications

  • Network product
  • A sound card and a computer motherboard.
  • Linear regulator source.
  • Controller.

78L05 circuit

78L05 circuit
78L05 circuit


  • (1) to determine the output voltage value, select the voltage value suffix (XX).
  • (2) in order to get the best stability and transient response, it is recommended to use the side capacitor and install it as far as possible.

How to use 78L05

Voltage controllers are regular in electronic circuits. They give a steady yield voltage to a fluctuated information voltage. For our situation the 78L05 IC is a notable controller IC that discovers its application in a large portion of the tasks. The name 78L05 connotes two meaning, “78” means that it is a positive voltage controller and “05” means that it gives 5V as yield. So our 7805 will give a +5V yield voltage.The yield current of this IC can go up to 100mA. Yet, the IC experiences substantial warmth misfortune thus a Heat sink is suggested for ventures that devour progressively current. For instance if the info voltage is 12V and you are expending 50mA, then (12-5) * (50*10^-3) = 0.35W. This 0.35 Watts will be dispersed as heat.Another prominent voltage controller is 7805 which is bulkier in size yet has high current rating of about 1A. Along these lines, on the off chance that you are searching for a littler bundle of voltage controller that has little flow rating in TO-92 bundle then this IC may be the correct decision.

The Electronic Project Using 78L05

The 78L05 is a three terminal voltage controller. The three terminals are Input, Output and ground as appeared in the 78L05 pinout chart. It is simple and straight forward to utilize this IC, simply interface the contribution to the information voltage which must be controlled and the ground stick to framework ground. The controlled 5V can be acquired from the yield stick if the IC. In the circuit underneath an info voltage of 12V is directed to 5V utilizing the 78L05. You utilize the 5V to power any little loads like LED which is evaluated for under 100mA. Since the greatest current that this IC could supply is just upto 100mA.

Electronic  Project Using  78L05
Electronic Project Using 78L05

Additionally note the Capacitors C1 and C2 are utilized at both the Input and yield end. These capacitors are utilized to channel any commotion that is combined with the Input voltage. It’s not compulsory to utilize the accurate estimation of capacitor yet an estimation of 10uF for C1 and 1uF for C2 would be a perfect decision. These controllers additionally can confine current and secure when the temperature surpasses past intersection temperature. So you in the event that associate high current burdens, at that point you can anticipate that the IC should get hot soon and shunt down in the end. In that utilizing a high present controller like 7805 would be a perfect decision. Aside from utilizing it as a voltage controller it can likewise be utilized as a present controller, impede, promoter circuit and even a variable voltage controller. The circuits for every one of these applications can be found at page 27/45 in the 78L05 datasheet given underneath.

78L05 datasheet

As the 78L05 datasheet appears: The 78L05 arrangement of three terminal positive controllers is accessible with a few fixed yield voltages making them valuable in a wide scope of utilizations. At the point when utilized as a zener diode/resistor blend substitution, the LM78LXX for the most part brings about a compelling yield impedance improvement of two sets of extent, and lower calm current. These controllers can give neighborhood on card guideline, disposing of the dissemination issues related with single point regulation.The voltages accessible enable the LM78LXX to be utilized in rationale frameworks, instrumentation, HiFi, and other strong state electronic hardware. 78L05 Features 78L05 in miniaturized scale SMD bundle Output voltage resistances of ±5% over the temperature range Output current of 100 mA Internal warm over-burden insurance Output transistor safe territory security Internal short out current cutoff Available in plastic TO-92 and plastic SO-8 low profile bundles No outside parts Output voltages of 5.0V, 6.2V, 8.2V, 9.0V, 12V, 15V See A 1112 for small scale SMD contemplations

The Market Price of 78L05

78L05 packagebrandprice
TO-92ST brand0.11 yuan /PCS
0.17 yuan /PCS

The three terminal regulator 78L05 has a high degree of concern on the web page, and the number of enquiries and quotations is frequent. The prices reported in different packages are also different. The average price of the TO-92 package for ST brand is 0.11 yuan /PCS, while the SOT89 packaging format is relatively high, and the average price is 0.17 yuan /PCS. According to the analysis of Huaqiang North index analyst, we should refer to Huaqiang North market.

The Way toTest 78l05 Voltage Regulator

Measuring Input Voltage

When testing the voltage of the regulator, we first check the voltage between the input pin and the ground. This is to ensure that the voltage is actually supplied to the regulator. If the regulator does not receive enough voltage, of course, it will not be able to output its rated regulating voltage. That’s why we did this test. In order to test the voltage entering the regulator, we use a multimeter to place it in the DC voltage setting. The DC voltage setting is the DC voltage symbol of the setting multimeter with the following symbols or symbols. We take out the probe of the multimeter, put the positive probe (usually the red probe) on the input pin of the regulator, and the negative probe (usually the black probe) on the ground pin. The voltage we should read should be higher than the rated output voltage of the regulator. This is usually 1-2 volts high. If we read higher voltage, the voltage regulator is receiving enough voltage to adjust the drop.

Measuring Output Voltage

Now that this step is complete, we are reading the output voltage. If the rated output of the regulator is 5 volts, we should read a voltage very close to 5 volts from the output. LM7805 is a voltage stabilizer with rated output voltage of 5 volts, so we should read this output. In order to measure the output voltage, we set the same multimeter as the DC voltage setting. Now we put the positive probe of the multimeter on the output pin of the regulator, and the negative probe on the ground pin of the regulator. We should now read the rated voltage of the regulator design or the voltage near it.

If the multimeter does read a voltage close to its rated output voltage, the voltage regulator functions normally and well.

The Way toTest 78l05 Voltage Regulator
The Way toTest 78l05 Voltage Regulator

If we don’t do this, the voltage regulator will fail because it doesn’t complete the design and outputs a regulated voltage.

The adjustable regulator can be tested in the same way. Unlike the fixed voltage regulator, the regulator can adjust the output voltage. What the user has to do is calculate the output of the regulator and perform the same test as shown above to see if it is good or defective.


17 thoughts on “How to Test 78l05 Voltage Regulator

  1. I see many different schematic diagrams, they have many different input and output capacitance values. So now I’m really confused. I just want to know what their purpose is.

    1. Hi~ Jasper
      About your question, the capacitor at the input provides a near-memory without a large number of inductances or resistors. This is important when the load suddenly changes the current it draws. The output capacitor smoothes the output voltage and is part of the closed-loop control of the voltage. Usually some minimum capacitors are needed to ensure the stability of the control circuit, but even if the frequency of the load current varies greatly, it can better maintain the voltage stability. There are two different caps for each location because they are designed to achieve a reasonable number of large-capacity storage and good high-frequency response.

  2. Hi~ here

    I’m trying to do a electronic circuit, and I would like to ask if I could use a 78S05 regulator instead of the 78L05? Or I need the 78L05 to realize this circuit.

    Best regards

    1. Good day, nino
      Please send me your circuit…

    2. I ordered a toolbox that had lost 78L05. Can I replace 7805, or do I need to adjust the upper limit?

      1. I am a newbie, and I would like to know what’s the difference between 7805 with 78l05? What’s their advantage and disadvantage?

  3. Good day!
    I have 500 78L05.
    Has anyone suggested an interesting circuit that uses a lot of 78L05? Or is it really impossible to use them for anything more interesting than simple voltage and current regulation circuits?

    Good luck~

  4. Thank you sir, thank you for providing valueful page, I am also doing an electronic project using 78l05 Voltage Regulator.

    1. Congratutations!

  5. I bought this 30 cm white LED light belt. Its voltage is set to 12 volts. The problem is that I want to use a 6 volt voltage. I can see that there are welded integrated circuit chips on it: an M7 chip and a 78L05 chip, from which I can find that the 78L05 chip is a voltage regulator. What’s the easiest way to get it running from 6 volts?

    1. In order to avoid the trouble of modifying a device to obtain different voltages, I would personally consider using a “boost” or boost DC-to-DC converter to simply provide the required voltage.

  6. Good post!

    1. I agree, the bloger always provide some valueful and interesting knowledge about IT and electronic components here. I have followed this blog.

      1. I am so happy to hear that, thank you very much.

  7. I am find some 78l05 manufacurers, could you recommend for me?

    1. Hi~ Mira
      I have sent email to you. Pls Check

  8. I’m troubleshooting a circuit with a 7805 in it. Voltages are good on it but it’s pretty warm. Normal ?

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