# CD4521BE

**Texas Instruments** · Counters / Dividers · DIP-16

CD4521BE from Texas Instruments, in a DIP-16. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | Q24 | output | Buffered counter output of stage 24 with count capacity 2^24 = 16,777,216. |
| 2 | RESET | input | A HIGH level resets the counter to the all-0s state and disables the oscillator, and the input is limited to -0.5 V to VDD +0.5 V. |
| 3 | VSS' | power_in | Oscillator Vss' pin brought out from the crystal oscillator to allow use of external resistors for low-power operation. |
| 4 | OUT 2 | output | Oscillator output 2 of the RC or crystal oscillator circuit, which can be tied to IN 2 in the functional test mode. |
| 5 | VDD' | power_in | Oscillator VDD' pin brought out from the crystal oscillator to allow use of external resistors for low-power operation. |
| 6 | IN 2 | input | Oscillator input 2 (counter clock input in the functional test mode), limited to -0.5 V to VDD +0.5 V with an input pulse frequency up to 2 MHz at 5 V, 5 MHz at 10 V and 6.5 MHz at 15 V. |
| 7 | OUT 1 | output | Oscillator output 1 used in the RC or crystal oscillator circuit. |
| 8 | VSS | power_in | Ground (negative supply) pin, the reference for the voltage ratings. |
| 9 | IN 1 | input | Oscillator input 1 that sets the RC or crystal oscillator configuration and must be tied HIGH or LOW when not in use. |
| 10 | Q18 | output | Buffered counter output of stage 18 with count capacity 2^18 = 262,144. |
| 11 | Q19 | output | Buffered counter output of stage 19 with count capacity 2^19 = 524,288. |
| 12 | Q20 | output | Buffered counter output of stage 20 with count capacity 2^20 = 1,048,576. |
| 13 | Q21 | output | Buffered counter output of stage 21 with count capacity 2^21 = 2,097,152. |
| 14 | Q22 | output | Buffered counter output of stage 22 with count capacity 2^22 = 4,194,304. |
| 15 | Q23 | output | Buffered counter output of stage 23 with count capacity 2^23 = 8,388,608. |
| 16 | VDD | power_in | Positive supply pin with a recommended range of 3 V to 18 V and an absolute maximum of -0.5 V to +20 V referenced to VSS. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | DIP-16 |
| Category | Logic ICs |
| Pins | 16 |

## CAD (KiCad official)

- Symbol: `CD4521BE`
- Footprint: `Package_DIP:DIP-16_W7.62mm`
- 3D model: DIP-16 (KiCad packages3D, STEP)
- 3D model files: `cd4521be-etched.step` / `cd4521be-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `cd4521be.step` / `cd4521be.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/cd4521b.pdf) (21 pp, sha256 `0f0f6fb3629f4701`, retrieved 2026-10-30, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (vision), consensus `claude-opus-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/cd4521be-datasheet.pdf)