7805 5 V regulator: specs and pinout
Fixed 5 V, 3-terminal positive linear regulator in a TO-220 package. It drops the extra input voltage as heat, so the usable current depends on how far the input is above 5 V.
Specs
| Spec | Value | Source |
|---|---|---|
| Output voltage | 4.8 V to 5.2 V (TJ = 25 C, 5 mA to 1 A load, VIN = 10 V); 4.75 V to 5.25 V over temperature | source Section 6.6 LM340 / LM7805 Electrical Characteristics (p.6) |
| Input voltage for regulation | 7.5 V to 20 V (limits quoted for the output-voltage rows) | source Section 6.6 Electrical Characteristics (p.6) |
| Maximum DC input voltage | 35 V (absolute maximum) | source Section 6.1 Absolute Maximum Ratings (p.4) |
| Maximum output current | Up to 1.5 A with adequate heat sinking | source Section 1 Features (p.1); Section 3 Description |
| Dropout voltage | 2 V at 1 A load (TJ = 25 C) | source Section 6.6 Electrical Characteristics (p.6) |
| Quiescent current | 8 mA max at 1 A load (TJ = 25 C) | source Section 6.6 Electrical Characteristics (p.6) |
| Thermal resistance, TO-220, junction to ambient | 54 C/W (absolute-maximum footnote); 23.9 C/W (thermal metric table, NDE package) | source Section 6.1 footnote 3 (p.4); Section 6.4 Thermal Information (p.4) |
| Power dissipation rule | PDMAX = (TJMAX - TA) / thetaJA; the part enters thermal shutdown if the die passes 150 C | source Section 6.1 footnote 3 (p.4) |
| Ambient operating temperature | 0 C to 125 C (LM340 / LM340A) | source Section 6.3 Recommended Operating Conditions (p.4) |
| Capacitors | 0.22 uF input capacitor if the regulator is far from the supply filter; 0.1 uF ceramic output capacitor helps transient response (not needed for stability) | source Section 1 Features; typical application note (p.1) |
Power
| Value | Source | |
|---|---|---|
| Supply | Input 7.5 V to 20 V for the rated 5 V output (35 V absolute maximum) | source Section 6.1, 6.6 (pp.4-6) |
| Current | 8 mA quiescent at 1 A load; output up to 1.5 A with heat sink | source Section 6.1, 6.6 (pp.4-6) |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.
No module: this is a bare 3-pin regulator. Pin order is the TO-220 package pinout from the TI LM340 / LM7805 family datasheet.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | Input | 7.5 V to 20 V for regulation; 35 V absolute maximum | Add 0.22 uF to ground if far from the supply filter. | source Pin Configuration, TO-220 (p.1) |
| 2 | Ground | 0 V | Tab connection is not stated in the TI pin table; do not tie it to another net. | source Pin Configuration (p.1) |
| 3 | Output | 5 V (4.8 V to 5.2 V at 25 C) | A 0.1 uF ceramic capacitor to ground helps transient response. | source Pin Configuration (p.1) |
Build with it
Project ideas for the 7805 5 V regulator. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Battery-powered 5 V rail for a small Uno sensor project: Heat math: 9 V in, 5 V out, budget 0.4 A total gives 4 V x 0.4 A = 1.6 W; at 54 C/W that is an 86 C rise, so the die stays under 125 C at room temperature. Keep the whole 5 V load under 0.4 A and check each module's own current. Fresh cells give about 9 V; once the pack drops below about 7.5 V the output is no longer held at 5 V.
- A test rig that measures the input and output current and voltage of a 7805 regulator feeding an Arduino Uno, using an INA226 module and an ESP32, and shows the heat loss on an OLED: Learning project. Load: the Uno board, powered from the regulator output at its 5 V pin (disconnect USB from the Uno while doing this). Input: the 6 AA pack, about 9 V. The INA226 measures one point at a time: place it in the input line to read input voltage and current, then move it to the output line to read output voltage and current. Heat in the regulator is (VIN - VOUT) x current, to compare against the 54 C/W thermal figure. Check the INA226 module's own shunt and voltage limits against 9 V before connecting. The ESP32 board and the OLED run from their own USB power, not from the 7805. Join the ESP32 GND to the battery pack negative (the INA226 GND) so the I2C signals share a ground.
- A light level display with an LDR, an Arduino Nano and an LCD powered from a 9 V battery through a 7805 regulator: A 9 V input gives 4 V x load current of heat: a Nano, LCD and LDR together stay well inside the 1.6 W budget at 0.4 A. Feed the 5 V pin of the Nano from pin 3 of the regulator, never the 9 V into the 5 V pin.
Common mistakes
- Pulling a high current from a high input voltage with no heat sink: heat in watts is (VIN - 5 V) x current. At 12 V in and 0.5 A that is 3.5 W; with 54 C/W that is a 189 C rise, far past the 150 C shutdown point (source)
- Feeding less than about 7 V: the part needs 2 V of dropout at 1 A, so a 5 V output is not held when the input sags, for example as batteries run down (source)
- Wiring the pins in the wrong order: TO-220 pin 1 is input, pin 2 is ground, pin 3 is output; check this against the TI pin table before power-up (source)
Not covered by the official source
- Maker of the supplied parts is not stated; the TI LM7805 family datasheet is used. The ST L78 datasheet was not used.
- The supplied package is TO-220; the datasheet's 54 C/W (footnote) and 23.9 C/W (table, NDE package) differ, and the more cautious 54 C/W is used for the heat math.
- Short-circuit current and some output-voltage figures are not used.
Sources
- link (TI SNOSBT0L, LM340, LM340A, LM7805, LM7812, LM7815 family, Feb 2000, revised Sep 2016)