7406 Hex inverter, open collector, 40 mA
The 7406 holds six inverters with open-collector outputs that can sink 40 mA and stand off up to 30 V. An open-collector output only ever pulls low; it needs a pull-up resistor or a load connected to the supply to go high.
7406 pinout
Top view of the 14-pin DIP package. Pin 1 is at the bottom left, beside the notch, and the numbers run anticlockwise. Power is on pin 14 (VCC, +5 V) and pin 7 (GND).
| Pin | Name | Type | What it is |
|---|---|---|---|
| 1 | 1A | Input | Input of gate 1 |
| 2 | 1Y | Output | Open collector output |
| 3 | 2A | Input | Input of gate 2 |
| 4 | 2Y | Output | Open collector output |
| 5 | 3A | Input | Input of gate 3 |
| 6 | 3Y | Output | Open collector output |
| 7 | GND | Ground | 0 V |
| 8 | 4Y | Output | Open collector output |
| 9 | 4A | Input | Input of gate 4 |
| 10 | 5Y | Output | Open collector output |
| 11 | 5A | Input | Input of gate 5 |
| 12 | 6Y | Output | Open collector output |
| 13 | 6A | Input | Input of gate 6 |
| 14 | VCC | Power | +5 V supply |
7406 truth table
| A | Y |
|---|---|
| 0 | 1 |
| 1 | 0 |
A 1 here means the output is off: it is pulled high only by an external pull-up resistor or load.
What the 7406 is used for
- Driving LEDs, lamps and relays directly from logic
- Driving the segments of a common-anode 7-segment display
- Wired-AND buses, where several outputs share one pull-up
Standard TTL, not LS: each input loads 1.6 mA. The outputs sink 40 mA, which is what it is for — driving LEDs and common-anode displays straight from logic.
Electrical summary
| Package | 14-pin DIP |
| Supply voltage | 5 V (4.75 V to 5.25 V) |
| Supply current, typical | 32 mA |
| Output type | Open collector — only pulls low; needs a pull-up resistor or a load to the supply |
| Output current, low | sinks up to 40 mA |
| Output current, high | none — the output does not drive high |
| Input current, low | 1.6 mA out of each input held low |
| Fan-out | one output can drive about 100 LS inputs |
Typical figures for quick reference when planning a board. Check the manufacturer's datasheet for limits and timing before committing a design.
Try the 7406 on a breadboard
The Breadboard Simulator has the 7406 in its parts library: seat it on a virtual breadboard, wire it, power the board and probe the pins before you build the real thing.