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LM7824: Description, Specs, Applications, Pinout

Generally, voltage regulators are electronic components that are common in the majority of electric circuits. They generate a constant output voltage from a wide-ranging input voltage. An example of the voltage regulator we’ll discuss today is the lm7824 voltage regulator IC. Lm7824 has several features such as overheat protection circuits, short circuit protection, etc., therefore a favorable option for users. 

We’ll get into an in-depth understanding of lm7824 in the following areas; pinout, features, applications, among others. 

What is lm7824?

Lm7824 is an IC voltage regulator with a fixed 24V DC output voltage. The IC also has a wide range of applications like commercial devices. It can additionally achieve adjustable voltage provided you incorporate external components despite primarily functioning as a fixed voltage regulator. 

It’s also good to note that 7824 has two meanings, and they are;

78 stands for a positive voltage regulator, while 24 signifies that the IC has a 24V output. 

lm7824 Pin Configuration

LM7824 1A voltage regulator IC has a three-terminal pin configuration comprising;

Pin1 / input (V+) – The input pin receives an unregulated input voltage from a power supply source. 

Pin2 / Ground – Pin2 connects to the ground line. 

Pin3/ Output (Vo) – The last pin generates a regulated output that’s 24V. 

lm7824 Features and Specifications

The technical specifications and features of the lm7824 voltage regulator IC are;

  • The output current capability is 1.5 Ampere. The maximum input current should range from 1.6 Amp to 2 Amp to maintain the output at 1.5A. 
  • Secondly, it is a 24V positive voltage regulator that generates a dropout voltage of 1.0A.
  • Line regulation and load regulation are at a maximum of 480 mV.
  • It has a low quiescent current at 8mA, and the quiescent current change ranges from 0.5 to 0.8mA. 
  • DCR (DC resistance) is at a maximum of 2.2 ohms, while the output Noise Voltage is 10Hzf -100kHz. 
  • The minimum input voltage is 33V, while the maximum input voltage ranges from 35V to 40V. 
  • It also has a built-in short circuit protection function and built-in overheat protection function. The latter ensures a constant junction temperature of 125°C maximum. 
  • Finally, it is available in TO-3, TO-220M-1 Unit, and KTE packages. 

lm7824 Equivalents

The equivalents or replacements of IC LM7824 are LM7806, LM7912, LM7809, L7812 L7815, MC7824, and L78S23CV. 

Furthermore, you can use the adjustable regulator LM317 IC for the fixed 24V. 

lm7824 as +24V Voltage Regulator

We’re now going to apply lm7824 IC in a circuit as a +24V voltage regulator. 

Hardware components 

  • IC LM7824
  • Capacitors – 330nF and 100nF
  • The power source is from a +27V to +40V Direct Current supply. 
Circuit of LM7824 IC as a +24V voltage regulator 

Circuit of LM7824 IC as a +24V voltage regulator 

We have two capacitors from the circuit diagram above, 0.1uf (output capacitor) and 0.33uf (input capacitor). The two are enough in operating the IC. 

0.33uf is a ceramic capacitor meaning it handles any input inductance problem. Similarly, 0.1uf is a ceramic capacitor but, it augments the circuit’s stability. 

Place the capacitors closer to the terminal to improve their functionality in the circuit. And, at all times, ensure the capacitors are ceramic because, compared to electrolytic capacitors, a ceramic type is faster. 

ceramic capacitors

(ceramic capacitors) 

electrolytic capacitors

(electrolytic capacitors) 

What to consider when using lm7824 IC in the circuit on a long-term. 

  • First, the load passing through the circuit shouldn’t be more than 1.5A.
  • Then, always install a suitable heatsink with the lm7824 IC to help heat dissipation. When there’s no huge heat sink, the thermal resistance becomes high since there’s a temperature rise beyond the ambient temperature. 
A passive copper and aluminum heatsink used to cool electronic components

(A passive copper and aluminum heatsink used to cool electronic components)

  • Thirdly, use the IC in temperature below +125°C and above 0°C.
  • Lastly, the IC’s storage temperature should range between -65°C and +125°C. 

Second application circuit using LM7824 IC

Our second example differs from the first one because we’ll include other hardware components here. 

In addition to an IC LM7824 and capacitors 330nF and 100F, we also have components like; 

  • Capacitor – 2200uF,
  • Diode – 1N4001,
  • Diode bridge – 2A,
  • Transformer – 24V 2A. 
Circuit of a 24V power supply using lm7824 IC 

Circuit of a 24V power supply using lm7824 IC 

How the circuit works

You’ll need a few external components to operate the circuit above since all the required hardware is in the IC. 

Then, you can also use a 110V to 24V DC transformer instead of a 230V to 24V 2A transformer. 

The IN4001 diode blocks feedback that should get to the IC. Diode D1, conversely, connects the 2A. 

The second will need a heatsink similar to the first circuit due to heat produced during operation. 

  1. lm7824 Applications

Lm7824 applications include the following;

  • Motor drivers,
  • Regulated dual supply,
  • 24V power supplies/constant +24V output regulators that power sensors,
  • Output polarity-reversal-protection circuit,
  • Solar applications,
  • Airplane applications, 
  • Adjustable output regulator,
  • Voltage step down applications, 
  • Current limiter for some applications, 
  • Battery chargers, and
battery charger and wire

(battery charger and wire)

Conclusion

Briefly, LM7824 is a 3-terminal 1A positive voltage regulator IC making a constant output voltage. They serve many basic electronic systems like power relays and battery chargers. Additionally, they are highly rated, well-priced products and reliable.

And while it may experience heavy heat loss during its operation, an attached heatsink can control the heat. 

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Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

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