Pinout diagram
Summary specifications
Full pin reference
| Pin | Name | Group | Direction | Levels | Description |
|---|---|---|---|---|---|
| 1 | VCC | Power | Power | +3 V to +15 V | Positive supply (VCC, equivalent to VDD on the rest of the 4000 series). TI's datasheet labels this pin VCC; on every other 4000-series part in this library the equivalent pin is called VDD and sits on the top-right corner (pin 14 or 16). Here it is on pin 1 (top-left) instead. Same rail, different name, different corner — do not confuse it with a separate supply domain. |
| 2 | 1Y | I/O | Output | CMOS push-pull | Inverter 1 output. Low when 1A is high. High-current sink: can drive TTL loads. |
| 3 | 1A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 1 input. The input high level can exceed VCC, allowing level conversion from a higher-voltage logic family. |
| 4 | 2Y | I/O | Output | CMOS push-pull | Inverter 2 output. Low when 2A is high. |
| 5 | 2A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 2 input. |
| 6 | 3Y | I/O | Output | CMOS push-pull | Inverter 3 output. Low when 3A is high. |
| 7 | 3A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 3 input. |
| 8 | VSS | Ground | Power | 0 V | Negative supply (ground). Note: this is pin 8, the usual ground pin, but paired with VCC on pin 1 rather than pin 16. |
| 9 | 4A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 4 input. |
| 10 | 4Y | I/O | Output | CMOS push-pull | Inverter 4 output. Low when 4A is high. |
| 11 | 5A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 5 input. |
| 12 | 5Y | I/O | Output | CMOS push-pull | Inverter 5 output. Low when 5A is high. |
| 13 | NC | No Connect | Not connected | No connection | No-connect. This pin is not connected internally; leave it floating or tie to any rail. |
| 14 | 6A | I/O | Input | CMOS, 0 V / VDD (input can exceed VDD) | Inverter 6 input. |
| 15 | 6Y | I/O | Output | CMOS push-pull | Inverter 6 output. Low when 6A is high. |
| 16 | NC | No Connect | Not connected | No connection | No-connect. This pin is not connected internally; leave it floating or tie to any rail. |
Common uses and repair diagnostics
The CD4049 is the 4000-series hex inverter, and it has the single most surprising pinout in this library. Every other part puts VDD on the top-right pin and VSS on the bottom-left; the CD4049 puts VDD on pin 1 (top-left) and VSS on pin 8 (bottom-left, the usual ground pin). Two pins — 13 and 16 — are no-connects. The part is a hex inverter with high-current outputs that can also be used as a CMOS-to-TTL level converter (the input high threshold can exceed VDD, so it accepts 5 V to 15 V logic on a 5 V supply), which is why it turns up in mixed-voltage boards where a plain 74LS04 will not do.
The CD4049 is the hex inverter you reach for when a board needs to invert signals between two different supply voltages. Its input high threshold can exceed VCC, so it accepts 12 V or 15 V CMOS logic on a 5 V supply and converts it down to 5 V levels — a job a plain 74LS04 cannot do because its inputs are clamped to VCC. It also has higher sink-current than a standard CMOS gate, so it can drive TTL loads directly, which is why it turns up in mixed CMOS/TTL boards and in level-shifting stages between CMOS logic and TTL peripherals.
The trap with the CD4049 is the supply pinout. VCC is on pin 1 (top-left), not pin 16 (top-right) as on every other 14- and 16-pin part in this library. A board laid out for a 74LS04 or CD4011 will put VCC on the wrong pin, and the chip will not power up. The two NC pins (13 and 16) are also unusual — pin 16 is the VCC pin on most 16-pin parts, but on the CD4049 it is a no-connect.
- Confirm pin 1 (VCC) is within 3 to 15 V and pin 8 (VSS) is at 0 V. The supply pins are NOT where most other parts put them — VCC is pin 1, not pin 16.
- Drive an input high and measure the output: it must pull low. Drive the input low and it must rise near VCC. A stuck level suggests a dead inverter.
- If the part does not power up, check that VCC is on pin 1 and not pin 16 — pin 16 is a no-connect on this part, and wiring VCC there gives a dead chip.
- Tie any unused inverter input to VSS or VCC; a floating CMOS input drifts and makes the output chatter, drawing destructive current.
- If the chip runs warm, suspect a floating input or an output shorted to another gate — CMOS should draw microamps at rest.