7805Fixed 5 V linear regulator
A stable 5 V rail from three connections.
7805 is a three-terminal linear regulator that supplies a nominal 5 V output from a higher DC input. This reference follows STMicroelectronics L7805C, with TO-220 and D²PAK package views and the correct input, ground and output connections. Inside the package, a reference, error amplifier and series pass stage continuously adjust the output. Current limiting, thermal protection and safe-operating-area protection are built in. Two small bypass capacitors complete the basic supply circuit. The voltage difference becomes heat, so input headroom and cooling must be checked together with load current.
Input supplyGround & tabRegulated output
L7805CVTO-220Front view · marking toward you · leads down
L7805CD2T-TRD²PAKTop view · thermal pad is pin 2 (GND)
Click a lead or use the arrow keys. Front view · marking toward you · leads down
PIN 1 · Input supply
Positive inputINPUT
Function
Feeds the series pass stage and its internal control circuit.
How to connect
Connect to the positive DC source. Place a 0.33 µF bypass capacitor between INPUT and GND, close to the regulator.
Electrical note
The input must remain sufficiently above 5 V, including ripple troughs.
PIN 2 · Ground & tab
Reference and returnGND
Function
Reference for the regulated output and return for the internal bias current. The exposed metal tab is connected to this pin.
How to connect
Connect to supply negative and the load return. Keep bypass capacitor returns short.
Electrical note
The TO-220 tab and D²PAK thermal pad are electrically GND; account for this when mounting a heatsink.
PIN 3 · Regulated output
Regulated outputOUTPUT
Function
Supplies a nominal 5 V while input headroom, current and thermal limits are satisfied.
How to connect
Connect the load and a 0.1 µF bypass capacitor to GND near the device.
Electrical note
Available current depends on input voltage, temperature, package and heatsinking; 1.5 A is not an unconditional continuous rating.
At a glance
Fixed 5 V linear regulator
The control circuit is inside the package; the external capacitors support the input and output at their connection points.
5 V nominalRegulated output
3 INPUT · GND · OUTPUTElectrical connections
0–125 °C · C gradeJunction operating range
2 V · 1 A · 25°CTypical dropout
Operating profile
L7805CV
Operating characteristics
Key parameters and their test conditions
- Nominal output
- 5 VConditions / notes: Fixed regulator
- Output at 25°C
- 4.8–5.2 VConditions / notes: VIN = 10 V; IOUT = 500 mA
- Output over specified range
- 4.75–5.25 VConditions / notes: IOUT = 5 mA to 1 A; VIN = 7–18 V; TJ = 0–125°C
- Operating junction temperature
- 0–125°CConditions / notes: Selected C-grade devices
- Minimum load
- 5 mAConditions / notes: Manufacturer regulation specification
- Typical dropout
- 2 VConditions / notes: IOUT = 1 A; TJ = 25°C
Package details
Follows the selected physical package
- Manufacturer
- STMicroelectronics
- Part number
- L7805CV
- Package
- TO-220
- Connections
- 3 pins
- Mounting
- Through-hole
- Lead pitch
- 2.54 mm
- Package code
- V
- Thermal reference
- See ST DS0422 package thermal data and actual cooling conditions
Connections by function
Select a pin to open its function, electrical notes and wiring guidance.
Input supply1 pins
Ground & tab1 pins
Regulated output1 pins
Input supply1 pins
Ground & tab1 pins
Regulated output1 pins
Compare against a reference
An internal reference supplies a stable comparison level. The error amplifier compares that level with feedback from the output.
Control the series pass stage
The amplifier adjusts the pass transistor to correct small load and input variations. Regulation requires input voltage above the output by sufficient headroom.
Manage the heat
The pass stage dissipates approximately (VIN − VOUT) × IOUT. Ground current adds a smaller term. Protection reduces stress during overloads but does not remove the need for thermal design.
At 9 V input and 100 mA load, the pass stage dissipates about 0.40 W before ground-current losses. A larger input voltage means more heat, not a higher regulated output.
Pin reference
Select a pin to explore its function and connection.
3 pins
| Pin | Signal | Type | Function |
|---|---|---|---|
| INPUT | Positive input | Feeds the series pass stage and its internal control circuit. | |
| GND | Reference and return | Reference for the regulated output and return for the internal bias current. The exposed metal tab is connected to this pin. | |
| OUTPUT | Regulated output | Supplies a nominal 5 V while input headroom, current and thermal limits are satisfied. |
No pins match. Try a signal name or choose All pins.
Operating characteristics
ST L7805C · conditions retained
Manufacturer specifications 6 parameters
| Parameter | Value | Conditions / notes |
|---|---|---|
| Nominal output | 5 V | Fixed regulator |
| Output at 25°C | 4.8–5.2 V | VIN = 10 V; IOUT = 500 mA |
| Output over specified range | 4.75–5.25 V | IOUT = 5 mA to 1 A; VIN = 7–18 V; TJ = 0–125°C |
| Operating junction temperature | 0–125°C | Selected C-grade devices |
| Minimum load | 5 mA | Manufacturer regulation specification |
| Typical dropout | 2 V | IOUT = 1 A; TJ = 25°C |
No specifications match. Try a parameter name or a unit.
Read the complete conditions in ST DS0422 Table 10. Junction temperature is not ambient temperature.
Regulation and noise
Typical values are not guaranteed limits
Manufacturer specifications 5 parameters
| Parameter | Value | Conditions / notes |
|---|---|---|
| Line regulation | 3 mV typical; 100 mV maximum | VIN = 7–25 V; TJ = 25°C; base test load 500 mA |
| Load regulation | 100 mV maximum | IOUT = 5 mA to 1.5 A; TJ = 25°C |
| Quiescent current | 8 mA maximum | TJ = 25°C |
| Ripple rejection | 62 dB minimum | VIN = 8–18 V; 120 Hz |
| Output noise | 40 µV per V of output, typical | 10 Hz–100 kHz; TJ = 25°C |
No specifications match. Try a parameter name or a unit.
Base test: VIN = 10 V, IOUT = 500 mA, CIN = 0.33 µF, COUT = 0.1 µF unless stated.
Basic 5 V supply
9 V DC input · 100 mA illustrative load
Manufacturer specifications 6 parameters
| Parameter | Value | Conditions / notes |
|---|---|---|
| Regulator | L7805CV | Front view: 1 INPUT, 2 GND, 3 OUTPUT |
| Input bypass | 0.33 µF | Between pins 1 and 2; close to the IC |
| Output bypass | 0.1 µF | Between pins 3 and 2; close to the IC |
| Example load | 50 Ω · at least 1 W | 5 V / 50 Ω = 100 mA; resistor dissipation = 0.5 W |
| Pass-stage heating | Approximately 0.40 W | (9 V − 5 V) × 0.1 A; excludes ground-current losses |
| Supply return | Common GND | Both capacitors, load and pin 2 share the return |
No specifications match. Try a parameter name or a unit.
This is a regulated DC input example, not a mains supply. Capacitor voltage ratings must suit their actual rails.
Thermal design
Package and board conditions matter
Manufacturer specifications 5 parameters
| Parameter | Value | Conditions / notes |
|---|---|---|
| Power estimate | PD ≈ (VIN − VOUT) × IOUT + VIN × IGND | Use appropriate measured or specified ground current |
| Temperature estimate | TJ ≈ TA + PD × RθJA | Only for the thermal conditions represented by RθJA |
| TO-220 junction-to-case | 5°C/W | Manufacturer thermal reference |
| D²PAK junction-to-case | 3°C/W | Manufacturer thermal reference |
| Protections | Current limiting, thermal shutdown, safe area | Not substitutes for heatsink and board design |
No specifications match. Try a parameter name or a unit.
A headline current rating does not describe every input-voltage and cooling combination.
Package and stress limits
L7805CV · TO-220
Manufacturer specifications 5 parameters
| Parameter | Value | Conditions / notes |
|---|---|---|
| Lead pitch | 2.54 mm | Through-hole; verify the chosen package drawing |
| Metal tab / thermal pad | GND · pin 2 | Electrically connected to the return |
| Input absolute maximum | 35 V | Stress limit for the 5 V member; not a recommended input |
| Storage temperature | −65 to +150°C | Unpowered |
| Pin assignment | 1 INPUT · 2 GND · 3 OUTPUT | Use the selected package orientation |
No specifications match. Try a parameter name or a unit.
Check the exact orderable part and footprint before manufacture. Other 78xx output voltages are separate devices.
Logic and interface rails
Provide a local 5 V rail where the source is sufficiently above 5 V and load power is modest.
Manufacturer application guideBench experiments
Demonstrate line regulation, load regulation and why a linear regulator becomes warm.
Manufacturer application guideOn-board auxiliary supplies
Create a simple low-noise supply while accounting for headroom, bypassing and heat.
Manufacturer application guideTake it into ProTech
Find 7805 in the Components Library to place its schematic symbol and connect its pins.
Reference page · circuit simulation model not yet availableOpen ProTech