What is the LM7805 Voltage Regulator?

The LM7805 is a voltage regulator that outputs +5 volts.

Like most other regulators in the market, it is a three-pin IC; input pin for accepting incoming DC voltage, ground pin for establishing ground for the regulator, and output pin that supplies the positive 5 volts.

Product Features:

  • 3-Terminal Regulators
  • Output Current up to 1.5A
  • Internal Thermal-Overload Protection
  • High Power-Dissipation Capability
  • Internal Short-Circuit Current Limiting
  • Output Transistor SAFE-Area Compensation

Fun Fact!

Have you spotted that the last two digits of the LM7805 are the same as the output voltage? It’s actually not a coincidence, but a way for people to easily remember the voltage outputs. The LM7805 is part of the LM78XX series of voltage regulators, where the XX indicates the voltage that each regulator outputs.

What you need to know when using the LM7805

Absolute Maximum Input Voltage

  • 35V

Recommended Operating Conditions

  • Input Voltage: Minimum 7V, Maximum 25V
  • Output Current: 1.5A
  • Operating Virtual Junction Temperature: Minimum 0, Maximum 125°C

Possible High Temperatures

  • If differences between the input and output voltages are not well managed, LM7805 can overheat, which may result in malfunctioning. Solutions Include:
    • Limiting input voltage to 2-3 volts above the output regulated voltage
    • Placing a heat sink in the circuit to dissipate heat solutions

LM7805: Linear or switching voltage regulator?

When it comes to voltage regulators, it is split into two types:

  1. Linear voltage regulator
  2. Switching voltage regulator

The LM7805 is a linear voltage regulator, but do you know what each of it is?

Below summarises:

Linear Regulators Switching Regulators
What are they Regulators that use linear, non switching techniques for regulation of voltage output from power supply Regulators that provide high efficiency through rapidly switching series element on and off
Design Flexibility Buck Buck, Boost, Buck-Boost
Efficiency Low to medium-high for low difference between voltages High
Complexity Low Medium to High
Cost Low, Cheap Medium to High
Noise Generated Low Medium to High
Usage Purpose Powering low powered devices
Applications that has minimal difference between input and output voltages
High effeciency, high power projects
Applications that has a higher voltage input range
Examples LM7805, LM317 LM3671

LM7805 Product Applications

LM7805 is applied in a wide range of circuits:

  • Fixed-Output Regulator
  • Positive Regulator in Negative Configuration
  • Adjustable Output Regulator
  • Current Regulator
  • Regulated Dual-Supply
  • Output Polarity-Reversal-Protection Circuit
  • Reverse bias projection Circuit

LM7805 can also be used in building circuits for inductance meter, phone chargers, portable CD player, etc.

Is LM7805 better than LM317?

The ability for adjustable voltage:

  • LM317 can give an adjustable output voltage in the range of 1.5V to 37V, where LM7805 can only give an output voltage of 5V

Output Current Capabilities:

  • LM317 has the capability to give output current more than 1.5A whereas LM7805 can only give output current only up to 1.5A

Components needed:

  • LM317 requires more external components (adjustment pot or precision resistors to set the voltage divider etc.) as compared to the LM7805

Verdict: LM317 provides more versatility but if you’re just looking for
a regulated 5V supply, LM7805 does the perfect job
.

Voltage Regulator Alternatives

Lipo Rider v1.3


If using the LM7805 or any other voltage regulator is not in your interest, the Lipo Rider v1.3 is able to supply a constant 5V output that’s similar as well. Not only that, the internal charger IC handles the power flow for you as well.

Features

  • Jst 2.0 connector
  • Stable 5V USB power supply regardless of source
  • Charge/Recharge algorithms built into chip
  • Charge Lithium Polymer Battery through solar power or USB
  • Stable supply voltage through either lithium battery or USB
  • 2 x USB ports let you program your kit while charging your Lithium battery
  • LED indications for battery full or charging states
  • Simple design means extremely affordable
  • Scalable to multiple lithium batteries and large/multiple solar panels through simple end-user modification

Summary

All in all, if you’re looking for a fuss-free 5V output and value for money option, the LM7805 by texas instruments is the one for you.

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